Study On Air Pollution Index Improvement Schemes

Air Pollution Index (API) is a method to reflect and evaluate air quality, which is a single number calculated by the concentrations of several monitored pollutants. It can represent the air quality condition quantificationally and intuitively.The APIs in mainland China are calculated only by the concentrations of SO₂, NO₂, PM₁₀. Sub-index of each pollutant is calculated by linear interpolation, and the maximum of those sub-indexes is the Air Pollution Index of the day. Comparing with the advanced air pollution/quality index systems in the other countries and regions, the current API has some problems such as less indicators, unreasonable calculation interval, weak warning, and inconsistent with the public's feeling. Therefore, five revision schemes of API were put forward in this paper using the calculation method and research achievements at home and abroad for air pollution/quality indexes.For the No.1 scheme, only the calculation interval of API was adjusted. For the No.2 scheme, CO and O₃ were added into the calculation. For the No.3-5 schemes, PM_2.5 was added, the limit of PM_2.5 concentration was varied from scheme No.3 to No.5. The Five revision schemes were evaluated using the air quality monitoring datum of Urumchi in 2009, Guangzhou in 2008 and 2009. The results indicated that scheme No.2 to No.5 could better reflect the air pollution status. For the No.3-5 schemes, the number of the days in which air quality met the standard decreased obviously, even by 50%. The local government would pay more attention to air quality control, and took effective measures to control the air pollution.Moreover, the online public investigation was established to collect public suggestions on API improvement. The results indicated that more than 70% people agreed to add CO, O₃, PM_2.5, and over 50% agreed to use the limit value of PM_2.5 concentration in our study. Therefore, the scheme NO.4 was the closest to the public perspective. The study suggested that we should test different schmes stagely to reflect urban air quality status effectively, and gradually filter out the best schme to replace the exsiting API.