The Environmental Protection Department (EPD) recommended mere tinkering for Hong Kong’s second Air Quality Objectives (AQO) review – tightening the concentration limits of two types of air pollutants—Sulfur Dioxide (SO2) and Fine Suspended Particulates (PM2.5)—from the current World Health Organization (WHO) Interim Target 1 to Interim Target 2; at the same time, the no. of exceedances allowed for PM2.5 is advised to be significantly increased from 9 to 35 times. No changes were recommended for other types of air pollutants.


The rationale behind EPD’s recommendation is simple: The Government projected that the level of SO2 and PM2.5 can attain the tightened level in 2025, thus recommended the tightening of the two pollutants. Since their projection showed that the concentration of PM10 and Ozone would be increasing in the future, further tightening on the two pollutants was therefore, not suggested. And the predicted no. of exceedance for PM2.5 in 2025 are 33 times, thus the Government recommended relaxing the allowed no. of exceedance from the current 9 times to 35 times.


The consequence of such practicability-based recommendations is that, our objectives will continue to fall short of World Health Organization’s safety standard and we can easily attain our objectives without having new or stronger emission reduction measures, and air pollution will continue to cause adverse impact on citizens’ health.


The World Health Organization (WHO) suggests a much stricter guideline regarding the notion of exceedance allowed for air pollutants. The WHO advisory did not make any provision for allowable exceedances for SO2, NO2 and ozone, and allows only 3 exceedances for PM2.5 and PM10 per year. The suggestion to relax allowable exceedances clearly violates WHO’s health-first principle and seems to conflict with Hong Kong Air Pollution Control Ordinance’s (APCO) interpretation on public interest.


According to APCO section 7A: the AQO review should serve the following 2 purposes: (a) promote the conservation of air in the zone in the public interest; and (b) promote the best use of air in the zone in the public interest.” Study conducted by the HKU School of Public Health showed that, raising the no. of exceedance would also increase the no. of high air pollution episodes. Therefore, the decision to greatly relax the allowable no. of exceedance for PM2.5 is a clear violation of the APCO and put public health at severe risk.


The objectives of the two air pollutants, PM10 and ozone, which EPD did not make changes to, are falling way behind the standards used by many western advanced countries. Our current PM10 (24-hour) concentration limit is on par with some of the developing countries, such as Turkey, Rwanda, Kenya and India; while we share a similar ozone standard with Dominican Republic, Venezuela, Bangladesh, and Mexico, which is even more loose than the standards in India and the Philippines. Without a doubt, Hong Kong is an advanced economy with an air quality standard of the “third world”.

PM10 concentration limit in various cities and countries

Ozone concentration limit in various cities and countries

Time to harmonize national ambient air quality standards for global health equity
Meltem Kutlar Joss 1,2, Marloes Eeftens 1,2, Emily Gintowt 1,2, Ron Kappeler 1,2, Nino Künzli 1,2


Read more:
 Hong Kong faces dilemma on Air Pollution
– 2018 Annual Air Quality Review & Response to AQO Review


Photo Credit/ Kit Ying Cheung

Story posted on
28th Jan, 2019


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