The results of EPA's analysis show that, with respect to compliance with the EGU NOX emission budgets in 2021, maximizing the use of existing operating SCRs provides the largest amount of ozone season NOX emission reductions (52 percent, affecting 60 units), and turning on idled SCRs produces an additional 34 percent (affecting 4 units) of the total ozone season NOX reductions. Generation shifting primarily from coal to gas generation (14 percent) makes up the remainder of the ozone season NOX reductions. Based on this analysis of how EGUs are expected to comply with the proposed Revised CSAPR Update, none of the Group 3 states are projected to hit their variability limits, nor bank significant allowances during the analysis period (2021-2025).
      In addition to the ozone season NOX reductions, there will also be reductions of other air emissions associated with EGUs burning fossil fuels (i.e., co-pollutants). These other emissions include the annual total changes in emissions of NOx and CO2; there are no annual SO2 and PM2.5 emissions changes. The emissions reductions are presented in Table 4-5. Consistent with the limited impact of generation shifting, there were de minimis emissions changes of CO, mercury, and HCl.
Table 4-5.	EGU Annual Emissions and Emissions Changes for NOX, SO2, PM2.5, and CO2 for the Regulatory Control Alternatives
                                  Annual NOX
                                (thousand tons)
                                Total Emissions
                             Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                     2021
12 States
                                                                            291
                                                                            274
                                                                            290
                                                                            274
                                                                            -17
                                                                             -2
                                                                            -17

Other States
                                                                            524
                                                                            524
                                                                            524
                                                                            524
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            815
                                                                            797
                                                                            813
                                                                            797
                                                                            -17
                                                                             -2
                                                                            -17
                                     2022
12 States
                                                                            289
                                                                            259
                                                                            287
                                                                            259
                                                                            -30
                                                                             -2
                                                                            -30

Other States
                                                                            521
                                                                            521
                                                                            521
                                                                            521
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            809
                                                                            780
                                                                            808
                                                                            780
                                                                            -30
                                                                             -2
                                                                            -30
                                     2023
12 States
                                                                            275
                                                                            249
                                                                            274
                                                                            249
                                                                            -27
                                                                             -2
                                                                            -27

Other States
                                                                            505
                                                                            505
                                                                            505
                                                                            505
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            780
                                                                            753
                                                                            778
                                                                            753
                                                                            -27
                                                                             -2
                                                                            -27
                                     2024
12 States
                                                                            268
                                                                            241
                                                                            266
                                                                            227
                                                                            -27
                                                                             -2
                                                                            -41

Other States
                                                                            500
                                                                            500
                                                                            500
                                                                            500
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            768
                                                                            741
                                                                            766
                                                                            727
                                                                            -27
                                                                             -2
                                                                            -41
                                     2025
12 States
                                                                            268
                                                                            241
                                                                            266
                                                                            227
                                                                            -27
                                                                             -2
                                                                            -41

Other States
                                                                            500
                                                                            500
                                                                            500
                                                                            500
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            768
                                                                            741
                                                                            766
                                                                            727
                                                                            -27
                                                                             -2
                                                                            -41

                                  Annual SO2
                                (thousand tons)
                                Total Emissions
                             Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                     2021
12 States
                                                                            376
                                                                            376
                                                                            376
                                                                            376
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            556
                                                                            556
                                                                            556
                                                                            556
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            933
                                                                            933
                                                                            933
                                                                            933
                                                                              0
                                                                              0
                                                                              0
                                     2022
12 States
                                                                            332
                                                                            332
                                                                            332
                                                                            332
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            492
                                                                            492
                                                                            492
                                                                            492
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            824
                                                                            824
                                                                            824
                                                                            824
                                                                              0
                                                                              0
                                                                              0
                                     2023
12 States
                                                                            302
                                                                            302
                                                                            302
                                                                            302
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            480
                                                                            480
                                                                            480
                                                                            480
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            781
                                                                            781
                                                                            781
                                                                            781
                                                                              0
                                                                              0
                                                                              0
                                     2024
12 States
                                                                            338
                                                                            338
                                                                            338
                                                                            338
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            534
                                                                            534
                                                                            534
                                                                            534
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            872
                                                                            872
                                                                            872
                                                                            872
                                                                              0
                                                                              0
                                                                              0
                                     2025
12 States
                                                                            338
                                                                            338
                                                                            338
                                                                            338
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            534
                                                                            534
                                                                            534
                                                                            534
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            872
                                                                            872
                                                                            872
                                                                            872
                                                                              0
                                                                              0
                                                                              0

                                 Annual PM2.5
                                (thousand tons)
                                Total Emissions
                             Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                     2021
12 States
                                                                             50
                                                                             50
                                                                             50
                                                                             50
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                             76
                                                                             76
                                                                             76
                                                                             76
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            126
                                                                            126
                                                                            126
                                                                            126
                                                                              0
                                                                              0
                                                                              0
                                     2022
12 States
                                                                             50
                                                                             50
                                                                             50
                                                                             50
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                             76
                                                                             76
                                                                             76
                                                                             76
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            125
                                                                            125
                                                                            125
                                                                            125
                                                                              0
                                                                              0
                                                                              0
                                     2023
12 States
                                                                             48
                                                                             48
                                                                             48
                                                                             48
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                             74
                                                                             74
                                                                             74
                                                                             74
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            122
                                                                            122
                                                                            122
                                                                            122
                                                                              0
                                                                              0
                                                                              0
                                     2024
12 States
                                                                             47
                                                                             47
                                                                             47
                                                                             47
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                             74
                                                                             74
                                                                             74
                                                                             74
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            121
                                                                            121
                                                                            121
                                                                            121
                                                                              0
                                                                              0
                                                                              0
                                     2025
12 States
                                                                             47
                                                                             47
                                                                             47
                                                                             47
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                             74
                                                                             74
                                                                             74
                                                                             74
                                                                              0
                                                                              0
                                                                              0

Total
                                                                            121
                                                                            121
                                                                            121
                                                                            121
                                                                              0
                                                                              0
                                                                              0

                                  Annual CO2
                                (thousand tons)
                                Total Emissions
                             Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                     2021
12 States
                                                                            478
                                                                            478
                                                                            478
                                                                            478
                                                                              0
                                                                              0
                                                                              0

Other States
                                                                            959
                                                                            959
                                                                            959
                                                                            959
                                                                              0
                                                                              0
                                                                              0

Total
                                                                          1,437
                                                                          1,437
                                                                          1,437
                                                                          1,437
                                                                              0
                                                                              0
                                                                              0
                                     2022
12 States
                                                                            507
                                                                            505
                                                                            506
                                                                            504
                                                                             -2
                                                                             -1
                                                                             -3

Other States
                                                                            985
                                                                            985
                                                                            985
                                                                            985
                                                                              0
                                                                              0
                                                                              0

Total
                                                                           1493
                                                                           1490
                                                                           1491
                                                                           1489
                                                                             -2
                                                                             -1
                                                                             -3
                                     2023
12 States
                                                                            537
                                                                            532
                                                                            534
                                                                            530
                                                                             -5
                                                                             -3
                                                                             -6

Other States
                                                                           1011
                                                                           1012
                                                                           1012
                                                                           1011
                                                                              0
                                                                              0
                                                                              0

Total
                                                                           1548
                                                                           1544
                                                                           1545
                                                                           1542
                                                                             -4
                                                                             -3
                                                                             -6
                                     2024
12 States
                                                                            532
                                                                            527
                                                                            528
                                                                            523
                                                                             -4
                                                                             -3
                                                                             -8

Other States
                                                                           1004
                                                                           1004
                                                                           1004
                                                                           1004
                                                                              0
                                                                              0
                                                                              0

Total
                                                                           1536
                                                                           1531
                                                                           1532
                                                                           1527
                                                                             -4
                                                                             -3
                                                                             -8
                                     2025
12 States
                                                                            526
                                                                            522
                                                                            523
                                                                            516
                                                                             -4
                                                                             -3
                                                                            -10

Other States
                                                                            996
                                                                            996
                                                                            996
                                                                            997
                                                                              0
                                                                              0
                                                                              0

Total
                                                                          1,523
                                                                          1,518
                                                                          1,519
                                                                          1,513
                                                                             -5
                                                                             -4
                                                                            -10

4.4.2	Impact of Emissions Reductions on Maintenance and Nonattainment Monitors
In 2021, there are two nonattainment receptors and two maintenance receptors (see section VI.C of the preamble for additional discussion). EPA evaluated the air quality improvements at the four receptors from projected compliance with the two regulatory alternatives at the highest EGU cost threshold levels (i.e., $1,600 per ton and $3,900 per ton). EPA found that the average air quality improvement at the four receptors relative to the engineering analytics baseline was 0.19 ppb at $1,600 per ton and 0.23 ppb at $3,900 per ton (see Table VII.D.1-1 in the preamble for additional discussion). EPA found that the one of the receptors (Westport, Connecticut receptor) remains nonattainment at all cost levels, another receptor the (Stratford, Connecticut receptor) switches from nonattainment to maintenance at $1,600 per ton (i.e., its average design value (DV) falls below the standard but its maximum DV remains above the NAAQS), while a third receptor (Houston receptor) remains maintenance at all levels.
EPA observes this $1,600 per ton level of stringency results in all downwind air quality problems for the 2008 ozone NAAQS being resolved after 2024 (one year earlier than the base case). There are also projected changes in receptor status (from projected nonattainment to maintenance-only) for the Stratford and Westport receptors (the first in 2021, the second in 2024). In addition, the Houston receptor changes from maintenance to attainment in 2023.
4.4.3	Compliance Cost Assessment
     The estimates of the changes in the cost of supplying electricity for the regulatory control alternatives are presented in Table 4-6. Since the rule does not result in any additional recordkeeping, monitoring or reporting requirements, the costs associated with compliance, monitoring, recordkeeping, and reporting requirements are not included within the estimates in this table and can be found in preamble Section VIII.C.6.
Table 4-6.	National Compliance Cost Estimates (millions of 2016$) for the Regulatory Control Alternatives

                         Revised CSAPR Update Proposal
                          More-Stringent Alternative
                          Less-Stringent Alternative
2021-2025 (Annualized)
                                     19.4
                                     80.6
                                      1.6
2021 (Annual)
                                     20.9
                                     37.2
                                      3.8
2022 (Annual)
                                     29.7
                                     49.2
                                     12.8
2023 (Annual)
                                     27.8
                                     47.3
                                     12.8
2024 (Annual)
                                      6.3
                                     132.2
                                     -12.0
2025 (Annual)
                                      6.3
                                     132.2
                                     -12.0
"2021-2025 (Annualized)" reflects total estimated annual compliance costs levelized over the period 2021 through 2025, discounted using a 4.25 real discount rate. This does not include compliance costs beyond 2025. "2021 (Annual)" through "2025 (Annual)" costs reflect annual estimates in each of those years.

     There are several notable aspects of the results presented in Table 4-6. The most notable result in Table 4-6 is that the estimated annual compliance costs for the less stringent alternative is negative (i.e., a cost reduction) in 2024 and 2025, although this regulatory control alternative reduces NOX emissions by over 2,000 tons as shown in Table 4-5. While seemingly counterintuitive, estimating negative compliance costs in a single year is possible given the assumption of perfect foresight. IPM's objective function is to minimize the discounted net present value (NPV) of a stream of annual total cost of generation over a multi-decadal time period. For example, with the assumption of perfect foresight it is possible that on a national basis within the model the least-cost compliance strategy may be to delay a new investment or retirement that was projected to occur sooner in the base case. Such a delay could result in a lowering of annual cost in an early time period and increase it in later time periods. Since the less-stringent alternative is designed to include only generation shifting, it does not necessitate full operation of existing controls, nor installation of new controls, leading to a negative total cost point estimate in 2025, reflecting the decision to delay retirements until later in the forecast period. Under the Revised CSAPR Update proposed rule, fully operating existing SCR controls provide a large share of the total emissions reductions. These options are selected in 2021, while upgrading to state-of-the-art combustion controls is assumed to begin in 2022. Generation shifting costs are positive in 2021 and 2023, but negative in 2025. The result is that the costs in 2021-23 are higher than costs in 2025.
     Under the more stringent alternative, while 2021 includes the same set of controls as under the Revised CSAPR Update proposed rule, a wider range of technologies is considered in subsequent years. This, combined with a more stringent cap driving generation shifting costs positive in every year, results in costs that grow over the 2021-25 period.
     As part of the IPM model runs, the Group 2 regional trading program was updated to exclude the 12-state Group 3 regional trading program, and budgets for the remaining Group 2 states were left otherwise unchanged. The Group 2 states did not exhibit significant changes in projected allowance prices and level and location of Group 2 NOX emissions between the baseline and regulatory alternatives as a result of this update.
     In addition to evaluating annual compliance cost impacts, EPA believes that a full understanding of these three regulatory control alternatives benefits from an evaluation of annualized costs over the 2021-2025 timeframe. Starting with the estimated annual cost time series, it is possible to estimate the net present value of that stream, and then estimate a levelized annual cost associated with compliance with each regulatory control alternative. For this analysis we first calculated the NPV of the stream of costs from 2021 through 2025 using a 4.25 percent discount rate. EPA typically uses a 3 and a 7 percent discount rate to discount future year social benefits and social costs in regulatory impact analyses (USEPA, 2010). In this cost annualization we use a 4.25 percent discount rate, which is consistent with the rate used in IPM's objective function for minimizing the NPV of the stream of total costs of electricity generation. This discount rate is meant to capture the observed equilibrium market rate at which investors are willing to sacrifice present consumption for future consumption and is based on a Weighted Average Cost of Capital (WACC). After calculating the NPV of the cost streams, the same 4.25 percent discount rate and 2021-2025 time period are used to calculate the levelized annual (i.e., annualized) cost estimates shown in Table 4-6.
     Additionally, note that the 2021-2025 equivalent annualized compliance cost estimates have the expected relationship to each other; the annualized costs are lowest for the less stringent alternative, and highest for the more stringent alternative.
4.4.4	Impacts on Fuel Use, Prices and Generation Mix
     While the Revised CSAPR Update proposal is expected to result in significant NOX emissions reductions, it is estimated to result in relatively modest impacts to the power sector. While these impacts are relatively small in percentage terms, consideration of these potential impacts is an important component of assessing the relative impact of the regulatory control alternatives. In this section we discuss the estimated changes in fuel use, fuel prices, generation by fuel type, capacity by fuel type, and retail electricity prices.
     Table 4-7 and Table 4-8 present the percentage changes in national coal and natural gas usage by EGUs in 2021. These fuel use estimates reflect a modest shift to natural gas from coal. The projected impacts in 2025 are similarly small.
Table 4-7.	2021 Projected U.S. Power Sector Coal Use for the Base Case and the Regulatory Control Alternatives

                                 Million Tons
                         Percent Change from Base Case

                                   Base Case
                         Revised CSAPR Update Proposal
                              Less-Stringent Alt.
                              More-Stringent Alt.
                         Revised CSAPR Update Proposal
                              Less-Stringent Alt.
                              More-Stringent Alt.
Appalachia
                                      85
                                      85
                                      85
                                      85
                                     0.16%
                                     0.11%
                                     0.36%
Interior
                                      115
                                      115
                                      115
                                      115
                                     0.00%
                                     0.01%
                                     0.05%
Waste Coal
                                       0
                                       0
                                       0
                                       0
                                     0.00%
                                     0.00%
                                     0.00%
West
                                      287
                                      286
                                      286
                                      286
                                    -0.08%
                                    -0.06%
                                    -0.20%
Total
                                      487
                                      487
                                      487
                                      487
                                    -0.02%
                                    -0.01%
                                    -0.04%

Table 4-8. 2021 Projected U.S. Power Sector Natural Gas Use for the Base Case and the Regulatory Control Alternatives
                              Trillion Cubic Feet
                         Percent Change from Base Case
                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                                             11
                                                                             11
                                                                             11
                                                                             11
                                                                          0.00%
                                                                          0.00%
                                                                          0.00%

     Table 4-9 and Table 4-10 present the projected coal and natural gas prices in 2021, as well as the percent change from the base case projected as a result of the regulatory control alternatives. These minor impacts in 2021 are consistent with the small changes in fuel use summarized above. The projected impacts in 2025 are similarly very small.
Table 4-9. 2021 Projected Minemouth and Power Sector Delivered Coal Price for the Base Case and the Regulatory Control Alternatives

                                    $/MMBtu
                         Percent Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
Minemouth
                                                                           1.21
                                                                           1.21
                                                                           1.21
                                                                           1.21
                                                                          0.08%
                                                                          0.06%
                                                                          0.22%
Delivered
                                                                           1.87
                                                                           1.87
                                                                           1.87
                                                                           1.87
                                                                          0.03%
                                                                          0.03%
                                                                          0.09%

Table 4-10. 2021 Projected Henry Hub and Power Sector Delivered Natural Gas Price for the Base Case and the Regulatory Control Alternatives

                                    $/MMBtu
                         Percent Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
Henry Hub
                                                                           3.19
                                                                           3.19
                                                                           3.19
                                                                           3.19
                                                                          0.00%
                                                                          0.00%
                                                                          0.02%
Delivered
                                                                           3.24
                                                                           3.24
                                                                           3.24
                                                                           3.24
                                                                          0.00%
                                                                          0.00%
                                                                          0.02%

     Table 4-11 presents the projected percentage changes in the amount of electricity generation in 2021 by fuel type. Consistent with the fuel use projections and emissions trends above, EPA projects a small overall shift from coal to gas. The projected impact in 2025 is similarly small.
Table 4-11. 2021 Projected U.S. Generation by Fuel Type for the Base Case and the Regulatory Control Alternatives

                               Generation (TWh)
                         Percent Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
Coal
                                                                            797
                                                                            797
                                                                            797
                                                                            797
                                                                        -0.003%
                                                                        -0.001%
                                                                         0.001%
Natural Gas
                                                                          1,582
                                                                          1,582
                                                                          1,582
                                                                          1,582
                                                                         0.001%
                                                                         0.003%
                                                                         0.002%
Nuclear
                                                                            740
                                                                            740
                                                                            740
                                                                            740
                                                                         0.000%
                                                                         0.000%
                                                                         0.000%
Hydro
                                                                            304
                                                                            304
                                                                            304
                                                                            304
                                                                         0.005%
                                                                        -0.001%
                                                                        -0.001%
Non-Hydro RE
                                                                            536
                                                                            536
                                                                            536
                                                                            536
                                                                         0.000%
                                                                         0.000%
                                                                         0.000%
Oil\Gas Steam
                                                                             58
                                                                             58
                                                                             58
                                                                             58
                                                                        -0.031%
                                                                        -0.072%
                                                                        -0.103%
Other
                                                                             34
                                                                             34
                                                                             34
                                                                             34
                                                                        -0.043%
                                                                        -0.042%
                                                                        -0.020%
Total
                                                                          4,051
                                                                          4,051
                                                                          4,051
                                                                          4,051
                                                                        -0.001%
                                                                         0.000%
                                                                        -0.001%
Note: In this table, "Non-Hydro RE" includes biomass, geothermal, landfill gas, solar, and wind.
     Table 4-12 presents the projected percentage changes in the amount of generating capacity in 2021 by primary fuel type. As explained above, none of the regulatory control alternatives are expected to have a net impact on overall capacity by primary fuel type in 2021, and the model was specified accordingly.
Table 4-12. 2021 Projected U.S. Capacity by Fuel Type for the Base Case and the Regulatory Control Alternatives

                                 Capacity (GW)
                         Percent Change from Base Case

                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
Coal
                                                                            216
                                                                            216
                                                                            216
                                                                            216
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Natural Gas
                                                                            421
                                                                            421
                                                                            421
                                                                            421
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Nuclear
                                                                             94
                                                                             94
                                                                             94
                                                                             94
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Hydro
                                                                            107
                                                                            107
                                                                            107
                                                                            107
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Non-Hydro RE
                                                                            184
                                                                            184
                                                                            184
                                                                            184
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Oil\Gas Steam
                                                                             74
                                                                             74
                                                                             74
                                                                             74
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Other
                                                                              8
                                                                              8
                                                                              8
                                                                              8
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Total
                                                                           1106
                                                                           1106
                                                                           1106
                                                                           1106
                                                                           0.0%
                                                                           0.0%
                                                                           0.0%
Note: In this table, "Non-Hydro RE" includes biomass, geothermal, landfill gas, solar, and wind

     EPA estimated the change in the retail price of electricity (2016$) using the Retail Price Model (RPM). The RPM was developed by ICF for EPA, and uses the IPM estimates of changes in the cost of generating electricity to estimate the changes in average retail electricity prices. The prices are average prices over consumer classes (i.e., consumer, commercial, and industrial) and regions, weighted by the amount of electricity used by each class and in each region. The RPM combines the IPM annual cost estimates in each of the 64 IPM regions with EIA electricity market data for each of the 22 electricity supply regions (shown in Figure 4-1) in the electricity market module of the National Energy Modeling System (NEMS).
      Table 4-13 and Table 4-14 present the projected percentage changes in the retail price of electricity for the three regulatory control alternatives in 2021 and 2025, respectively. Consistent with other projected impacts presented above, average retail electricity prices at both the national and regional level are projected to be small. By 2025, EPA estimates that this rule will result in a 0.02 percent increase in national average retail electricity price, or by about 0.02 mills/kWh.

Table 4-13. Average Retail Electricity Price by Region for the Base Case and the Regulatory Control Alternatives, 2021

                     2021 Average Retail Electricity Price
                         Percent Change from Base Case

                               (2016 mills/kWh)

Region
                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
MROE
                                                                            118
                                                                            118
                                                                            118
                                                                            118
                                                                             0%
                                                                             0%
                                                                             0%
NYCW
                                                                            166
                                                                            166
                                                                            166
                                                                            166
                                                                             0%
                                                                             0%
                                                                             0%
NYLI
                                                                            134
                                                                            134
                                                                            134
                                                                            134
                                                                             0%
                                                                             0%
                                                                             0%
NYUP
                                                                            109
                                                                            109
                                                                            109
                                                                            109
                                                                             0%
                                                                             0%
                                                                             0%
RFCE
                                                                            115
                                                                            115
                                                                            115
                                                                            115
                                                                             0%
                                                                             0%
                                                                             0%
RFCM
                                                                             91
                                                                             91
                                                                             91
                                                                             91
                                                                             0%
                                                                             0%
                                                                             0%
RFCW
                                                                             93
                                                                             93
                                                                             93
                                                                             93
                                                                             0%
                                                                             0%
                                                                             0%
SRDA
                                                                             83
                                                                             83
                                                                             83
                                                                             83
                                                                             0%
                                                                             0%
                                                                             0%
SRGW
                                                                             87
                                                                             87
                                                                             87
                                                                             87
                                                                             0%
                                                                             0%
                                                                             0%
SRCE
                                                                             85
                                                                             85
                                                                             85
                                                                             85
                                                                             0%
                                                                             0%
                                                                             0%
SRVC
                                                                            100
                                                                            100
                                                                            100
                                                                            100
                                                                             0%
                                                                             0%
                                                                             0%
SPSO
                                                                             88
                                                                             88
                                                                             88
                                                                             88
                                                                             0%
                                                                             0%
                                                                             0%
NATIONAL
                                                                            100
                                                                            100
                                                                            100
                                                                            100
                                                                             0%
                                                                             0%
                                                                             0%

Table 4-14. Average Retail Electricity Price by Region for the Base Case and the Regulatory Control Alternatives, 2025

                     2025 Average Retail Electricity Price
                         Percent Change from Base Case

                               (2016 mills/kWh)

Region
                                                                      Base Case
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
                                                  Revised CSAPR Update Proposal
                                                     Less-Stringent Alternative
                                                     More-Stringent Alternative
MROE
                                                                            116
                                                                            116
                                                                            116
                                                                            116
                                                                             0%
                                                                             0%
                                                                             0%
NYCW
                                                                            198
                                                                            198
                                                                            198
                                                                            198
                                                                             0%
                                                                             0%
                                                                             0%
NYLI
                                                                            159
                                                                            159
                                                                            159
                                                                            159
                                                                             0%
                                                                             0%
                                                                             0%
NYUP
                                                                            135
                                                                            135
                                                                            134
                                                                            134
                                                                             0%
                                                                             0%
                                                                             0%
RFCE
                                                                            132
                                                                            132
                                                                            132
                                                                            132
                                                                             0%
                                                                             0%
                                                                             0%
RFCM
                                                                            105
                                                                            105
                                                                            105
                                                                            105
                                                                             0%
                                                                             0%
                                                                             1%
RFCW
                                                                            104
                                                                            104
                                                                            104
                                                                            104
                                                                             0%
                                                                             0%
                                                                             0%
SRDA
                                                                             83
                                                                             83
                                                                             83
                                                                             83
                                                                             0%
                                                                             0%
                                                                             0%
SRGW
                                                                             98
                                                                             97
                                                                             97
                                                                             97
                                                                             0%
                                                                             0%
                                                                             0%
SRCE
                                                                             83
                                                                             83
                                                                             83
                                                                             83
                                                                             0%
                                                                             0%
                                                                             0%
SRVC
                                                                            101
                                                                            101
                                                                            101
                                                                            101
                                                                             0%
                                                                             0%
                                                                             0%
SPSO
                                                                             93
                                                                             93
                                                                             93
                                                                             93
                                                                             0%
                                                                             0%
                                                                             0%
NATIONAL
                                                                            107
                                                                            107
                                                                            107
                                                                            107
                                                                             0%
                                                                             0%
                                                                             0%

Figure 4-1. Electricity Market Module Regions
Source: EIA (http://www.eia.gov/forecasts/aeo/pdf/nerc_map.pdf)

4.5 Social Costs
     As discussed in EPA's Guidelines for Preparing Economic Analyses, social costs are the total economic burden of a regulatory action (USEPA, 2010). This burden is the sum of all opportunity costs incurred due to the regulatory action, where an opportunity cost is the value lost to society of any goods and services that will not be produced and consumed as a result of reallocating some resources towards pollution mitigation. Estimates of social costs may be compared to the social benefits expected as a result of a regulation to assess its net impact on society. The social costs of a regulatory action will not necessarily be equal to the expenditures by the electricity sector to comply with the rule. Nonetheless, here we use compliance costs as a proxy for social costs.
     The compliance cost estimates for the proposed and more or less stringent regulatory control alternatives presented in this chapter are the change in expenditures by the electricity generating sector required by the power sector for compliance under each alternative. The change in the expenditures required by the power sector to maintain compliance reflect the changes in electricity production costs resulting from application of NOX control strategies, including changes in expenditures resulting from changes in the mix of fuels used for generation, necessary to comply with the emissions budgets. Ultimately, part of the compliance costs may be borne by electricity consumers through higher electricity prices. As discussed above, the electricity and fossil fuel price impacts from this proposed rule are expected to be small.
4.6	Limitations
     EPA's modeling is based on expert judgment of various input assumptions for variables whose outcomes are uncertain. As a general matter, the Agency reviews the best available information from engineering studies of air pollution controls and new capacity construction costs to support a reasonable modeling framework for analyzing the cost, emission changes, and other impacts of regulatory actions.
     The IPM-projected annualized cost estimates of private compliance costs provided in this analysis are meant to show the increase in production (generating) costs to the power sector in response to the proposed rule. To estimate these annualized costs, EPA uses a conventional and widely accepted approach that applies a capital recovery factor (CRF) multiplier to capital investments and adds that to the annual incremental operating expenses. The CRF is derived from estimates of the cost of capital (private discount rate), the amount of insurance coverage required, local property taxes, and the life of capital. The private compliance costs presented earlier are EPA's best estimate of the direct private compliance costs of the proposed rule.
     As discussed in section 4.3.2, IPM v6 does not have the capacity to endogenously determine whether or not to maximize the use of existing EGU post-combustion NOX controls (i.e., SCR), or install/upgrade combustion controls in response to a regulatory control requirement. These decisions were imposed exogenously on the model, as documented in section 4.3.2 and Ozone Transport Policy Analysis TSD. While the emissions projections reflect operation of these controls, the projected compliance costs were supplemented with exogenously estimated costs of maximizing SCR operation and installing/upgrading combustion controls (see section 4.3.3). As a result of this modeling approach, the dispatch decisions made within the model do not take into consideration the additional operating costs associated with these two types compliance strategies (the operating costs of the units on which these strategies are imposed do not reflect the additional costs of these strategies). The effect of changes in facility and system-wide emissions from these changes in operating costs are also not accounted for in the spatial fields for the regulatory alternatives described in Chapter 3. These additional costs and their influence on projected changes in emissions and the level and location of ozone and PM2.5 concentration patterns from the regulatory alternatives are relatively minor, and do not have a significant impact on the overall finding that the economic impacts of this proposed rule are minimal.
     Additionally, the modeling includes two emission reduction strategies that are exogenously imposed where applicable: turning on idled SCRs (Revised CSAPR Update proposal and more-stringent alternative) and turning on idled SNCRs (mores stringent alternative only). While these strategies are exogenously imposed, the operation of controls is imposed in IPM and the costs and emissions reductions are estimated outside of IPM. Since the costs of these strategies are accounted for within the model, they are able to influence the projected behavior of the EGUs within the model.
     The annualized cost of the final rule, as quantified here, is EPA's best assessment of the cost of implementing the rule. These costs are generated from rigorous economic modeling of changes in the power sector due to implementation of the Revised CSAPR Update proposal.
4.7	References
U.S. Energy Information Administration (EIA). 2014. The Electricity Market Module of the National Energy Modeling System: Model Documentation 2014. Available at: <http://www.eia.gov/forecasts/aeo/nems/documentation/electricity/pdf/m068(2014).pdf>. Accessed 9/17/2015.
U.S. EPA, 2015. Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units (Final Rule), http://www2.epa.gov/cleanpowerplan/clean-power-plan-existing-power-plants.
U.S. EPA, 2015a. Standards of Performance for Greenhouse Gas Emissions from New, Modified, and Reconstructed Stationary Sources: Electric Utility Generating Units (Final Rule), http://www2.epa.gov/cleanpowerplan/carbon-pollution-standards-new-modified-and-reconstructed-power-plants.
U.S. EPA, 2015b. Disposal of Coal Combustion Residuals from Electric Utilities (Final Rule), http://www2.epa.gov/coalash/coal-ash-rule.
U.S. EPA, 2015c. Steam Electric Power Generating Effluent Guidelines (Final Rule), http://www2.epa.gov/eg/steam-electric-power-generating-effluent-guidelines-2015-final-rule.
U.S. EPA, 2014. Final Rule for Existing Power Plants and Factories, http://www2.epa.gov/cooling-water-intakes.
U.S. EPA, 2011. Cross-State Air Pollution Rule, http://www3.epa.gov/airtransport/CSAPR/index.html
U.S. EPA, 2011a. Mercury and Air Toxics Standards (MATS), http://www3.epa.gov/mats/.
U.S. EPA. 2010. EPA Guidelines for Preparing Economic Analyses. Available at: <http://yosemite.epa.gov/ee/epa/eed.nsf/webpages/guidelines.htm>. Accessed 9/21/2015.
U.S. EPA. 2010a. Regulatory Impact Analysis for the Proposed Federal Transport Rule Analyses. Available at: < http://www3.epa.gov/ttnecas1/ria.html>. Accessed 9/21/2015.
U.S. EPA, 2005. Clean Air Interstate Rule, http://archive.epa.gov/airmarkets/programs/cair/web/html/index.html.

--------------------------------------------------------------------------------
CHAPTER 5:  BENEFITS
Overview
This action proposes to revise the Cross-State Air Pollution Rule (CSAPR) Update to reduce the emissions of nitrogen oxides (NOX) transported from states that contribute significantly to nonattainment or interfere with maintenance of the 2008 ozone National Ambient Air Quality Standard (NAAQS) in downwind states. Implementing the Revised CSAPR Update proposed rule is expected to reduce emissions of NOX and provide ozone reductions, as well as consequent reductions in fine particulate matter (PM2.5) concentrations and carbon dioxide (CO2) emissions. This chapter describes the methods used to estimate the domestic climate benefits from reductions of CO2 emissions. Data, resource, and methodological limitations prevent EPA from monetizing health benefits from reducing concentrations of ozone and PM2.5, as well as the benefits of reducing direct exposure to NO2, ecosystem effects and visibility impairment as well as benefits from reductions in other pollutants, such as hazardous air pollutants (HAP). We qualitatively discuss these unquantified benefits in this chapter. However, to provide perspective regarding the scope of the estimated benefits, Appendix 5B illustrates the potential health effects associated with the change in PM2.5 and ozone concentrations as calculated using methods developed prior to the 2019 PM ISA and 2020 Ozone ISA. The values of these estimated benefits are not reflected in the estimated net benefits reported in Tables 7-1 and 7-2.
      This chapter reports the estimated monetized domestic climate benefits associated with emission reductions for the three regulatory control alternatives across several discount rates.
5.1	Estimated Climate Benefits from Reducing CO2
We estimate the climate for this proposed rulemaking using a measure of the domestic social cost of carbon (SC-CO2). The SC-CO2 is a metric that estimates the monetary value of projected impacts associated with marginal changes in CO2 emissions in a given year. The SC-CO2 includes a wide range of anticipated climate impacts, such as net changes in agricultural productivity and human health, property damage from increased flood risk, and changes in energy system costs, including reduced costs for heating and increased costs for air conditioning. The metric is typically used to assess the avoided damages as a result of regulatory actions (i.e., benefits of rulemakings that lead to an incremental reduction in cumulative global CO2 emissions). The SC-CO2 estimates presented in this RIA focus on the projected impacts of climate change that are anticipated to directly occur within U.S. borders.
The SC-CO2 estimates used in this analysis are interim values developed under Executive Order (EO) 13783 for use in regulatory analyses until an improved estimate of the impacts of climate change to the U.S. can be developed based on the best available science and economics. EO 13783 directed agencies to ensure that estimates of the social cost of greenhouse gases used in regulatory analyses "are based on the best available science and economics" and are consistent with the guidance contained in OMB Circular A-4, "including with respect to the consideration of domestic versus international impacts and the consideration of appropriate discount rates" (EO 13783, Section 5(c)). In addition, EO 13783 withdrew the technical support documents (TSDs) used in the benefits analysis of the 2016 CSAPR Update rule (U.S. EPA, 2016b) for describing the global social cost of greenhouse gas estimates developed under the prior Administration as no longer representative of government policy.
Regarding the two analytical considerations highlighted in EO 13783  -  how best to consider domestic versus international impacts and appropriate discount rates  -  current guidance in OMB Circular A-4 is as follows. Circular A-4 states that analysis of economically significant proposed and final regulations "should focus on benefits and costs that accrue to citizens and residents of the United States." (OMB, 2003) EPA follows this guidance by adopting a domestic perspective in our central analysis. Regarding discount rates, Circular A-4 states that regulatory analyses "should provide estimates of net benefits using both 3 percent and 7 percent." (OMB, 2003) The 7 percent rate is intended to represent the average before-tax rate of return to private capital in the U.S. economy. The 3 percent rate is intended to reflect the rate at which society discounts future consumption, which is particularly relevant if a regulation is expected to affect private consumption directly. EPA follows this guidance below by presenting estimates based on both 3 and 7 percent discount rates in the main analysis. See Appendix 5A for a discussion of the modeling steps involved in estimating the domestic SC-CO2 estimates based on these discount rates. These SC-CO2 estimates developed under EO 13783 and presented below will be used in regulatory analysis until more comprehensive domestic estimates can be developed, which would take into consideration recent recommendations from the National Academies of Sciences et al. (2017) to further update the current methodology to ensure that the SC-CO2 estimates reflect the best available science.
Table 5-1 presents the average domestic SC-CO2 estimate across all of the integrated assessment model runs used to estimate the SC-CO2 for each discount rate for the years 2015 to 2050. As with the global SC-CO2 estimates, the domestic SC-CO2 increases over time because future emissions are expected to produce larger incremental damages as economies grow and physical and economic systems become more stressed in response to greater climate change.
EPA estimated the dollar value of the CO2-related effects for each analysis year between 2021 and 2025 by applying the SC-CO2 estimates, shown in Table 5-1, to the estimated changes in CO2 emissions in the corresponding year under the regulatory options. EPA then calculated the present value and annualized benefits from the perspective of 2020 by discounting each year-specific value to the year 2020 using the same 3 percent and 7 percent discount rates.
Table 5-1. Interim Domestic Social Cost of Carbon Values (2016$/Metric Tonne CO2)
Year
3% Discount Rate, Average
7% Discount Rate, Average
2020
$7
$1
2025
$7
$1
2030
$8
$1
2035
$9
$2
2040
$9
$2
2045
$10
$2
2050
$11
$2
Note: These SC-CO2 values are stated in $/metric tonne CO2 and rounded to the nearest dollar (1 metric tonne equals 1.102 short tons). The estimates vary depending on the year of CO2 emissions and are defined in real terms, i.e., adjusted for inflation using the GDP implicit price deflator. EPA interpolated annual values for intermediate years.
Source: U.S. EPA Analysis, 2020 based on U.S. EPA, 2019b

The limitations and uncertainties associated with the SC-CO2 analysis, which were discussed in the 2016 CSAPR Update RIA (U.S. EPA, 2016b), likewise apply to the domestic SC-CO2 estimates presented in this chapter. Some uncertainties are captured within the analysis, as discussed in Appendix 5A, while other areas of uncertainty have not yet been quantified in a way that can be modeled. For example, limitations include the incomplete way in which the integrated assessment models capture catastrophic and non-catastrophic impacts, their incomplete treatment of adaptation and technological change, the incomplete way in which inter-regional and intersectoral linkages are modeled, uncertainty in the extrapolation of damages to high temperatures, and inadequate representation of the relationship between the discount rate and uncertainty in economic growth over long time horizons. The science incorporated into these models understandably lags behind the most recent research, and the limited amount of research linking climate impacts to economic damages makes this comprehensive global modeling exercise even more difficult. These individual limitations and uncertainties do not all work in the same direction in terms of their influence on the SC-CO2 estimates. In accordance with guidance in OMB Circular A-4 on the treatment of uncertainty, Appendix 5A provides a detailed discussion of the ways in which the modeling underlying the development of the SC-CO2 estimates used in this RIA addressed quantified sources of uncertainty and presents a sensitivity analysis to show consideration of the uncertainty surrounding discount rates over long time horizons.
Recognizing the limitations and uncertainties associated with estimating the SC-CO2, the research community has continued to explore opportunities to improve SC-CO2 estimates. Notably, the National Academies of Sciences, Engineering, and Medicine conducted a multidiscipline, multi-year assessment to examine potential approaches, along with their relative merits and challenges, for a comprehensive update to the current methodology. The task was to ensure that the SC-CO2 estimates that are used in Federal analyses reflect the best available science, focusing on issues related to the choice of models and damage functions, climate science modeling assumptions, socioeconomic and emissions scenarios, presentation of uncertainty, and discounting. In January 2017, the Academies released their final report, "Assessing Approaches to Updating the Social Cost of Carbon," and recommended specific criteria for future updates to the SC-CO2 estimates, a modeling framework to satisfy the specified criteria, and both near-term updates and longer-term research needs pertaining to various components of the estimation process (National Academies of Sciences et al., 2017).
The Academies' 2017 report also discussed the challenges in developing domestic SC-CO2 estimates, noting that current integrated assessment models do not model all relevant regional interactions  -  i.e., how climate change impacts in other regions of the world could affect the United States, through pathways such as global migration, economic destabilization, and political destabilization. The Academies concluded that it "is important to consider what constitutes a domestic impact in the case of a global pollutant that could have international implications that impact the United States. More thoroughly estimating a domestic SC-CO2 would therefore need to consider the potential implications of climate impacts on, and actions by, other countries, which also have impacts on the United States." (National Academies of Sciences et al., 2017, pg. 12-13). In addition to requiring reporting of impacts at a domestic level, Circular A-4 states that when an agency "evaluate[s] a regulation that is likely to have effects beyond the borders of the United States, these effects should be reported separately" (OMB, 2003; page 15). This guidance is relevant to the valuation of damages from CO2 and other greenhouse gases (GHGs), given that GHGs contribute to damages around the world independent of the country in which they are emitted. Therefore, in accordance with this guidance in OMB Circular A-4, Appendix 5A presents the global climate benefits from this proposed rule using global SC-CO2 estimates based on both 3 and 7 percent discount rates. EPA did not quantitatively project the full impact of the proposed rule on international trade and the location of production, so it is not possible to present analogous estimates of international costs resulting from the regulatory options. However, to the extent that the electricity market analysis endogenously models international electricity and natural gas trade (see Chapter 4), and to the extent that affected firms have some foreign ownership, some of the costs accruing to entities outside U.S. borders is captured in the technology implementation costs presented in the RIA (U.S. EPA, 2020c).
Table 5-2 shows the estimated monetary value of the estimated changes in CO2 emissions in 2021 and 2025 for the Revised CSAPR Update, the more-stringent alternative, and the less-stringent alternative.
Table 5-2. Estimated Domestic Climate Benefits from Changes in CO2 Emissions 2021 - 2025 (Millions of 2016$)
                               Regulatory Option
                                     Year
                               3% Discount Rate
                               7% Discount Rate
                                   Proposal
                                     2021
                                      0.3
                                      0.0

                                     2022
                                     14.9
                                      2.3

                                     2023
                                     30.0
                                      4.8

                                     2024
                                     31.4
                                      5.1

                                     2025
                                     32.9
                                      5.4
More-Stringent Alternative
                                     2021
                                      0.8
                                      0.1

                                     2022
                                     21.6
                                      3.4

                                     2023
                                     43.1
                                      6.8

                                     2024
                                     57.1
                                      9.2

                                     2025
                                     71.5
                                     11.7
                          Less-Stringent Alternative
                                     2021
                                      0.2
                                      0.0

                                     2022
                                      9.4
                                      1.5

                                     2023
                                     18.9
                                      3.0

                                     2024
                                     22.1
                                      3.6

                                     2025
                                     25.5
                                      4.2

Table 5-3 shows the total annualized monetary values associated with changes in CO2 emissions for the three regulatory options. EPA annualized monetary value estimates to enable consistent reporting across benefit categories (e.g., benefits from reduction in NOx emissions). The annualized values for the Revised CSAPR update rule are $22.1 million and $3.6 million, using discount rates of 3 and 7 percent, respectively.
Table 5-3. Estimated Total Annualized Domestic Climate Benefits (2021-25) from Changes in CO2 Emissions (Millions of 2016$)
                               Regulatory Option
                               3% Discount Rate
                               7% Discount Rate
                                   Proposal
                                     22.1
                                      3.6
                          More-Stringent Alternative
                                     38.9
                                      6.3
                          Less-Stringent Alternative
                                     15.3
                                      2.5

5.2 	Unquantified Benefits
      The monetized benefits estimated in this RIA reflect a subset of benefits attributable to the climate benefits from reductions associated with CO2. The proposal is also expected to reduce emissions of ozone season NOX. In the presence of sunlight, NOX and volatile organic compounds (VOCs) can undergo a chemical reaction in the atmosphere to form ozone. Reducing NOX emissions generally reduces human exposure to ozone and the incidence of ozone-related health effects, though the degree to which ozone is reduced will depend in part on local levels of VOCs as discussed in Chapter 3. The proposal would also reduce emissions of NOX throughout the year. Because NOX is also a precursor to formation of ambient PM2.5, reducing these emissions would reduce human exposure to ambient PM2.5 throughout the year and would thus reduce the incidence of PM2.5-attributable health effects. Reducing emissions of NOX would also reduce ambient exposure to NO2 and its associated health effects.
      Data, time, and resource limitations prevented EPA from quantifying the estimated impacts or monetizing estimated benefits associated with exposure to ozone, PM2.5, and NO2 (independent of the role NO2 plays as precursors to PM2.5), as well as ecosystem effects, and visibility impairment due to the absence of air quality modeling data for these pollutants in this analysis. Lack of quantification does not imply that there are no benefits associated with reductions in exposures to ozone, PM2.5, or NO2. In this section, we provide a qualitative description of these benefits, which are listed in Table 5-4. However, to provide perspective regarding the scope of the estimated benefits, Appendix 5B illustrates the potential health effects associated with the change in PM2.5 and ozone concentrations as calculated using methods developed prior to the 2019 PM ISA and 2020 Ozone ISA.
Table 5-4. Unquantified Health and Welfare Benefits Categories
                                   Category
                                    Effect
                               Effect Quantified
                               Effect Monetized
                               More Information
Premature mortality from exposure to PM2.5
Adult premature mortality
                                       --
                                       --
PM ISA[1][,2]

Infant mortality
                                       --
                                       --
PM ISA[1][,2]
Morbidity from exposure to PM2.5
Non-fatal heart attacks
                                       --
                                       --
PM ISA[1][,2]

Hospital admissions -- respiratory
                                       --
                                       --
PM ISA[1][,2]

Hospital admissions -- cardiovascular
                                       --
                                       --
PM ISA[1][,2]

Emergency room visits for asthma
                                       --
                                       --
PM ISA[1][,2]

Acute bronchitis
                                       --
                                       --
PM ISA[1][,2]

Lower respiratory symptoms
                                       --
                                       --
PM ISA[1][,2]

Upper respiratory symptoms
                                       --
                                       --
PM ISA[1][,2]

Exacerbated asthma
                                       --
                                       --
PM ISA[1][,2]

Lost work days
                                       --
                                       --
PM ISA[1][,2]

Minor restricted-activity days
                                       --
                                       --
PM ISA[1][,2]

Chronic Bronchitis
                                       --
                                       --
PM ISA[2]

Emergency room visits for cardiovascular effects
                                       --
                                       --
PM ISA[2]

Strokes and cerebrovascular disease
                                       --
                                       --
PM ISA[2]

Other cardiovascular effects
                                       --
                                       --
PM ISA[3]

Other respiratory effects (e.g., pulmonary function, non-asthma ER visits, non-bronchitis chronic diseases, other ages and populations)
                                       --
                                       --
PM ISA[3]

Reproductive and developmental effects (e.g., low birth weight, pre-term births, etc.)
                                       --
                                       --
PM ISA[3][,][4]

Cancer, mutagenicity, and genotoxicity effects
                                       --
                                       --
PM ISA[3][,][4]
Mortality from exposure to ozone
Premature mortality based on short-term study estimates
                                       --
                                       --
Ozone ISA[1][,2]

Premature mortality based on long-term study estimate
                                       --
                                       --
Ozone ISA[1][,2]
Morbidity from exposure to ozone
Hospital admissions -- respiratory causes
                                       --
                                       --
Ozone ISA[1][,2]

Emergency department visits for asthma
                                       --
                                       --
Ozone ISA[1][,2]

Exacerbated asthma
                                       --
                                       --
Ozone ISA[1][,2]

Minor restricted-activity days
                                       --
                                       --
Ozone ISA[1][,2]

School absence days
                                       --
                                       --
Ozone ISA[1][,2]

Decreased outdoor worker productivity
                                       --
                                       --
Ozone ISA[2]

Other respiratory effects (e.g., premature aging of lungs)
                                       --
                                       --
Ozone ISA[3]

Cardiovascular and nervous system effects
                                       --
                                       --
Ozone ISA[3]

Reproductive and developmental effects
                                       --
                                       --
Ozone ISA[3][,][4]
Improved Human Health

Reduced incidence of morbidity from exposure to NO2
Asthma hospital admissions
                                       --
                                       --
NO2 ISA[2]

Chronic lung disease hospital admissions
                                       --
                                       --
NO2 ISA[2]

Respiratory emergency department visits
                                       --
                                       --
NO2 ISA[2]

Asthma exacerbation
                                       --
                                       --
NO2 ISA[2]

Acute respiratory symptoms
                                       --
                                       --
NO2 ISA[2]

Premature mortality
                                       --
                                       --
NO2 ISA[2][,][3][,][4]

Other respiratory effects (e.g., airway hyperresponsiveness and inflammation, lung function, other ages and populations)
                                       --
                                       --
NO2 ISA[3][,][4]
Improved Environment

Reduced visibility impairment
Visibility in Class 1 areas
                                       --
                                       --
PM ISA[2]

Visibility in residential areas
                                       --
                                       --
PM ISA[2]
Reduced effects on materials
Household soiling
                                       --
                                       --
PM ISA[2][,][3]

Materials damage (e.g., corrosion, increased wear)
                                       --
                                       --
PM ISA[3]
Reduced effects from PM deposition (metals and organics)
Effects on Individual organisms and ecosystems
                                       --
                                       --
PM ISA[3]
Reduced vegetation and ecosystem effects from exposure to ozone
Visible foliar injury on vegetation
                                       --
                                       --
Ozone ISA[2]

Reduced vegetation growth and reproduction
                                       --
                                       --
Ozone ISA[2]

Yield and quality of commercial forest products and crops
                                       --
                                       --
Ozone ISA[2]

Damage to urban ornamental plants
                                       --
                                       --
Ozone ISA[3]

Carbon sequestration in terrestrial ecosystems
                                       --
                                       --
Ozone ISA[2]

Recreational demand associated with forest aesthetics
                                       --
                                       --
Ozone ISA[3]

Other non-use effects

Ozone ISA[3]

Ecosystem functions (e.g., water cycling, biogeochemical cycles, net primary productivity, leaf-gas exchange, community composition)
                                       --
                                       --
Ozone ISA[3]
Reduced effects from acid deposition
Recreational fishing
                                       --
                                       --
NOx SOx ISA[2]

Tree mortality and decline
                                       --
                                       --
NOx SOx ISA[3]

Commercial fishing and forestry effects
                                       --
                                       --
NOx SOx ISA[3]

Recreational demand in terrestrial and aquatic ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Other non-use effects

NOx SOx ISA[3]

Ecosystem functions (e.g., biogeochemical cycles)
                                       --
                                       --
NOx SOx ISA[3]
Reduced effects from nutrient enrichment
Species composition and biodiversity in terrestrial and estuarine ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Coastal eutrophication
                                       --
                                       --
NOx SOx ISA[3]

Recreational demand in terrestrial and estuarine ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Other non-use effects

NOx SOx ISA[3]

Ecosystem functions (e.g., biogeochemical cycles, fire regulation)
                                       --
                                       --
NOx SOx ISA[3]
Reduced vegetation effects from ambient exposure to SO2 and NOx
Injury to vegetation from SO2 exposure
                                       --
                                       --
NOx SOx ISA[3]

Injury to vegetation from NOx exposure
                                       --
                                       --
NOx SOx ISA[3]

Improved Human Health

Reduced incidence of morbidity from exposure to NO2
Asthma hospital admissions
                                       --
                                       --
NO2 ISA[2]

Chronic lung disease hospital admissions
                                       --
                                       --
NO2 ISA[2]

Respiratory emergency department visits
                                       --
                                       --
NO2 ISA[2]

Asthma exacerbation
                                       --
                                       --
NO2 ISA[2]

Acute respiratory symptoms
                                       --
                                       --
NO2 ISA[2]

Premature mortality
                                       --
                                       --
NO2 ISA[2][,][3][,][4]

Other respiratory effects (e.g., airway hyperresponsiveness and inflammation, lung function, other ages and populations)
                                       --
                                       --
NO2 ISA[3][,][4]
Improved Environment

Reduced visibility impairment
Visibility in Class 1 areas
                                       --
                                       --
PM ISA[2]

Visibility in residential areas
                                       --
                                       --
PM ISA[2]
Reduced effects on materials
Household soiling
                                       --
                                       --
PM ISA[2][,][3]

Materials damage (e.g., corrosion, increased wear)
                                       --
                                       --
PM ISA[3]
Reduced effects from PM deposition (metals and organics)
Effects on Individual organisms and ecosystems
                                       --
                                       --
PM ISA[3]
Reduced vegetation and ecosystem effects from exposure to ozone
Visible foliar injury on vegetation
                                       --
                                       --
Ozone ISA[2]

Reduced vegetation growth and reproduction
                                       --
                                       --
Ozone ISA[2]

Yield and quality of commercial forest products and crops
                                       --
                                       --
Ozone ISA[2]

Damage to urban ornamental plants
                                       --
                                       --
Ozone ISA[3]

Carbon sequestration in terrestrial ecosystems
                                       --
                                       --
Ozone ISA[2]

Recreational demand associated with forest aesthetics
                                       --
                                       --
Ozone ISA[3]

Other non-use effects

Ozone ISA[3]

Ecosystem functions (e.g., water cycling, biogeochemical cycles, net primary productivity, leaf-gas exchange, community composition)
                                       --
                                       --
Ozone ISA[3]
Reduced effects from acid deposition
Recreational fishing
                                       --
                                       --
NOx SOx ISA[2]

Tree mortality and decline
                                       --
                                       --
NOx SOx ISA[3]

Commercial fishing and forestry effects
                                       --
                                       --
NOx SOx ISA[3]

Recreational demand in terrestrial and aquatic ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Other non-use effects

NOx SOx ISA[3]

Ecosystem functions (e.g., biogeochemical cycles)
                                       --
                                       --
NOx SOx ISA[3]
Reduced effects from nutrient enrichment
Species composition and biodiversity in terrestrial and estuarine ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Coastal eutrophication
                                       --
                                       --
NOx SOx ISA[3]

Recreational demand in terrestrial and estuarine ecosystems
                                       --
                                       --
NOx SOx ISA[3]

Other non-use effects

NOx SOx ISA[3]

Ecosystem functions (e.g., biogeochemical cycles, fire regulation)
                                       --
                                       --
NOx SOx ISA[3]
Reduced vegetation effects from ambient exposure to SO2 and NOx
Injury to vegetation from SO2 exposure
                                       --
                                       --
NOx SOx ISA[3]

Injury to vegetation from NOx exposure
                                       --
                                       --
NOx SOx ISA[3]
1 These endpoints are generally quantified and monetized when EPA quantitatively characterizes the benefits of changes in PM2.5 and Ozone.
[2] We assess these benefits qualitatively due to data and resource limitations for this RIA.
3 We assess these benefits qualitatively because we do not have sufficient confidence in available data or methods.
[4] We assess these benefits qualitatively because current evidence is only suggestive of causality or there are other significant concerns over the strength of the association.

The proposed Revised CSAPR Update is expected to reduce concentrations of both ground-level ozone and fine particles (PM2.5) (see Chapter 3). EPA historically has used conclusions of the most recent Integrated Science Assessment (ISA) to inform its approach for quantifying air pollution-attributable health, welfare and environmental impacts associated with that pollutant. There is a separate ISA for each of the criteria pollutants. The ISA synthesizes the epidemiologic, controlled human exposure and experimental evidence "...useful in indicating the kind and extent of identifiable effects on public health or welfare which may be expected from the presence of [a] pollutant in ambient air."
The ISA uses a weight of evidence approach to assess the extent to the evidence supports conclusions about the likelihood that a given criteria pollutant causes a given health outcome. EPA generally estimates the number and economic value of the effects for which the ISA identifies the pollutant as having "causal" or "likely to be causal" relationship. The endpoints for which the 2020 final Ozone ISA (U.S. EPA, 2020b) and the 2019 final PM ISA (U.S. EPA, 2019a) identified as being causal or likely causal differed in some cases the endpoints for which those pollutants were identified as being causal or likely causal in the Ozone and PM ISAs completed for the previous NAAQS reviews (Tables 5-5 and 5-6). EPA traditionally uses the ISAs' characterizations of the health and ecological literature to identify individual studies that may be of sufficient quality for use in supporting PM or ozone benefits analysis.