The air quality health index (AQHI) system in Hong Kong : as a replacement of air pollution index (API), does it provide trustable and useful information to the public?

Abstract

Air Pollution Index (API) as an official air pollution indicator had been used for almost twenty years in Hong Kong. However, since the end of 2013, Air Quality Health Index (AQHI) has replaced the API because the AQHI is believed to provide more timely and useful pollution information to the public (EPD 2015). After this new system (AQHI) has been implemented, the frequency of sever air quality warning is decreased because the number of occurrence of serious air pollution has been sharply decreased in 2014 based on indication of the AQHI system. In other words, the air quality must have been improved in that year. Nevertheless, this consequence does not convince the public because the distrust about the new system itself rises among the public. Has the air quality in Hong Kong truly been improved or the Government just tries to alleviate the public’s dissatisfaction of the air quality through a new system that works with a looser standard. To eliminate the distrust about the new system, it is important to prove whether the air quality has been truly improved or not, and then disclose the real face of the doubt, telling the public the truth. In this study, I have collected daily, monthly and annually concentration of five air pollutants (NOx, SO2, O3, CO, and RSP) of period from year 2010 to 2015 in five general stations including Western/Central, Tsuen Wan, Tap Mun, Yuen Long, Tung Chung, and one roadside station Mong Kok. Located at separate islands, these six stations form a square frame covering main areas of Hong Kong which can be considered as good representation of the whole area of the city. When being analyzed and graphed into lines, these data can perfectly indicate the trends of the concentration of air pollutants at this time period, and may also possibly foresee the future development of air quality as well. With respect to the trendline that results from the analysis of concentrations of these five air pollutants, the average concentration of some air pollutants has been decreased (NOx, SO2, RSP) while some others been steadily increasing as well such like ozone and carbon monoxide. Overall, when calculating the difference of increase and reduction, the result shows that the total amount of concentration decreased is larger than the amount of concentration increased. Corresponded with the decreased number of serious air pollution occurrence, better air quality is directly indicated by the AQHI system as well. It is believable that the air quality in Hong Kong has been truly improved in 2014. The data released by the new system is reliable and credible.