The main vision of the Clean Air Network is to strive for cleaner and healthier air for the people of Hong Kong. We must identify the roots of the problem, in order to find the correct cures and thus advancing social progress. We think that modern progress on air pollution has nothing to do with your political views, your geographical location, nor does it have to do with your culture, because we’re all in this together, and air pollution is an epidemic that concerns everyone. We must adopt an analytical and scientific attitude, to further understand the real cause of air pollution, as to solve the problem.

Nevertheless, in a discussion of current affairs in Hong Kong, whenever something involves Mainland China, the discussion immediately revolves around the conflicts of the Mainland and Hong Kong. According research by PRAISE, from Hong Kong Science and Technology University, sixty percent of regional air pollutants in Hong Kong come from the Mainland. However due to differences in meteorological conditions, China’s influence on air pollution in Hong Kong fluctuates daily. We constantly emphasize that China is not the sole reason for Hong Kong’s dire pollution situation, but if one were to observe the nonstop hubbub and chatter of mainstream media, the blaming of the pollution in Hong Kong is very often put on others, namely the Mainland, and a blind eye is blatantly turned towards local pollution issues. We are very concerned that the Hong Kong government will misunderstand and misinterpret these discussions on mainstream media, and disregard Hong Kong’s mission to reduce emissions.

On May 6th and 10th, air pollution levels obliterated local regulations. According to a short-term health risk assessment jointly developed by HKUST, CUHK and the EPD, citizens were most affected in the early morning and in the afternoon, namely by nitrogen dioxide and ozone. We also published air quality level figures from Macau and Hong Kong, and found that PM2.5 and nitrogen dioxide levels in Hong Kong during most of those two days surpassed air pollution levels in cities such as Guangdong and Shenzhen. We could then come to the conclusion that Hong Kong’s main pollutants don’t originate from the Pearl River Delta, and it is very possible that these pollutants were all emitted locally.

The pollution levels recorded at 10 am by the short-term health risk assessment that was jointly developed by HKUST, CUHK and EPD.

The pollution levels recorded at 3 pm by the short-term health risk assessment that was jointly developed by HKUST, CUHK and EPD.

Our analysis and studies were assisted by numerous organizations. On today’s NOW news channel on current affairs (時事全方位), Green Power director Cheng points out that due to the influence of the high pressure ridge in the South Pacific, south winds blow from Hong Kong, forming isobars between urban areas and northwest New Territories, while north winds gush in from districts north of these isobars such as Yuen Long, Tuen Mun, and Tung Chung. This makes it extremely difficult for air pollutants to be blown away, and coupled with the city’s high density, the street canyon effect, local emission of nitrogen dioxide, and chemical reactions between suspended particles and sunlight, it’s a perfect concoction for the extreme concentration of ozone and photochemical smog that has coalesced in our city.

From a macro point of view regarding various air pollutants, Pearl River Delta and the Mainland are not responsible for pollution in Hong Kong. According to research the Hong Kong Science and Technology University conducted in 2016, involving an analysis of the nitrogen dioxide emission of Hong Kong and the Pearl River Delta, 61.9% to 84.4% of nitrogen dioxide in Hong Kong is produced locally. Nitrogen dioxide is one of the main sources of PM2.5. Generally regional emission of PM2.5 is higher in the fall and winter, and local emissions are higher in the spring and summer.



Regional air quality live release platform in Guangdong, Hong Kong and Macau.

Roadside pollution is very serious in Hong Kong, and although the government has invested heavily to counter this problem, nitrogen dioxide emissions are still going strong, and roadside pollution levels in Hong Kong have never reached local standards in the last twenty years, and nitrogen dioxide levels are double of WHO requirements, and are severely affecting the health of Hong Kong citizens. One big factor in Hong Kong’s pollution situation is the never ending growth of vehicle numbers in the city, with numbers reaching 800,000. This will only cause serious traffic congestion, and will serve as a negative impact on our health.

We are very pleased to see the public actively engaged in discussions regarding local air pollution, and have observed the rapid increase of analyses and data available to the public on the internet. Not only can the public access air quality levels published by the Environmental Protection Department (, and a regional air quality live release platform jointly published by the Guangdong, Hong Kong and Macau governments (, the public can also refer to the concentration levels of various pollutants in the Pearl River Delta, available every hour. We can also interpret and assess the health impacts caused by varied pollutants in our city’s districts, through a short-term health risk assessment jointly developed by HKUST, CUHK and the EPD.

We hope the public and the local government can finally and fully understand the enormity and severity of roadside pollution in Hong Kong, and at the same time we will also continue to strive for healthier air, and hope to improve local air quality.

Story posted on
18th May, 2017


Hong Kong has the highest PM2.5 annual mean across major cities in 2016

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