 Fig. 4. Station to station variation in pollutants concentration during the four time periods. Here (a), (b), (c), (d), and (e) show the mean station values for P19 vs. P20 periods, while (f), (g), (h), (i), and (j) correspond to L19 vs. L20 for PM2.5, PM10, SO2, NO2, and CO respectively. Error bars show the standard deviation. PM10 data is missing for station 5, 6, and 16 for both the years. 2019 data is missing for, PM10 at station 9, SO2at station 3, and CO at station 7.