 Moreover, the EPD made forecasts of the API for the following day everyday.The API was based on the level of 6 atmospheric pollutants, namely sulphur dioxide (SO2), nitrogen dioxide (NO2), respirable suspended particulates, carbon monoxide (CO), ozone (O3), lead (Pb), measured at all the monitoring stations throughout the territory.It was replaced by the Air Quality Health Index on 30 December 2013.