Mr. FONG Kin Wa, JP
Assistant Director (Air Quality Management)
Environment Protection Department
E-mail: kwfong@epd.gov.hk
Green Power, a local charitable green group, has been monitoring the Air Quality Health Index (AQHI) and the previous Air Pollution Index (API) data for over two decades. Enclosed with this letter is a brief report produced by Green Power regarding our AQHI analyses, i.e. A Brief Review of AQHI Data of Hong Kong for 2025.
From the past AQHI statistics provided by EPD for 15 General Air Quality Monitoring Stations (General Stations) during 2014-2025, both the total number of HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) decreased from their top levels in 2014 and fluctuated considerably until 2020. The range of variation has narrowed and kept at a lower level since 2021 and declined to 2080 hours and 379 days respectively in 2025. Such trend revealed that the health risk of the public associated with air pollution has been moderated in recent years.
A rare dust storm event in Hong Kong occurred in April, 2025 and all the "Serious" indices, i.e. hourly AQHI=10+, in 2025 were recorded during this event. If the HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) records attributable to the dust storm were excluded, 2025 was the first year without AQHI=10+ record since 2014, and 2025 was the lowest year for both HR hours and HR days figures (i.e. 1210 hours and 321 days respectively).
In 2025, four of the top five districts in terms of total number of HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) were situated in the northern part of the New Territories (NT) and North Lantau, namely Yuen Long, Tuen Mun, Tung Chung and Northern. Regarding the number of hours recorded AQHI reaching 10+, Yuen Long, Tuen Mun and Tung Chung were also amongst the top very often. Therefore, more proactive measures should be introduced in these areas in addition to the proposed Environmentally Friendly Transport Services (EFTS).
Under climate change, the association of HR days with hot weather became more obvious in recent years. Prolonged hot weather condition favours the formation of ozone in the South China that attributed to most of the PHR in HR days in Hong Kong.
We appreciate that the policies, legislations and measures having undertaken by the Administration improved the local air quality significantly. However, district concerns, especially for NDAs, and effect of climate change on air quality are still outstanding. The Administration should focus on reducing the precursors of ozone, i.e. nitrogen dioxide and volatile organic compounds, and combating the physical conditions in favour of ozone formation, e.g. prolonged hot and dry weather.
For any queries, please contact the undersigned at Green Power (T: 3961 0200, Fax: 2314 2661, Email: info@greenpower.org.hk)
Thank you very much for your kind attention. I look forward to the Administration’s policies to further relieve the health risk of the public associated with air quality.
Green Power, a local charitable green group, has been monitoring the Air Quality Health Index (AQHI) and the previous Air Pollution Index (API) data for over two decades. Enclosed with this letter is a brief report produced by Green Power regarding our AQHI analyses, i.e. A Brief Review of AQHI Data of Hong Kong for 2025.
From the past AQHI statistics provided by EPD for 15 General Air Quality Monitoring Stations (General Stations) during 2014-2025, both the total number of HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) decreased from their top levels in 2014 and fluctuated considerably until 2020. The range of variation has narrowed and kept at a lower level since 2021 and declined to 2080 hours and 379 days respectively in 2025. Such trend revealed that the health risk of the public associated with air pollution has been moderated in recent years.
A rare dust storm event in Hong Kong occurred in April, 2025 and all the "Serious" indices, i.e. hourly AQHI=10+, in 2025 were recorded during this event. If the HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) records attributable to the dust storm were excluded, 2025 was the first year without AQHI=10+ record since 2014, and 2025 was the lowest year for both HR hours and HR days figures (i.e. 1210 hours and 321 days respectively).
In 2025, four of the top five districts in terms of total number of HR hours (hourly AQHI ≥7) and HR days (daily maximum AQHI ≥7) were situated in the northern part of the New Territories (NT) and North Lantau, namely Yuen Long, Tuen Mun, Tung Chung and Northern. Regarding the number of hours recorded AQHI reaching 10+, Yuen Long, Tuen Mun and Tung Chung were also amongst the top very often. Therefore, more proactive measures should be introduced in these areas in addition to the proposed Environmentally Friendly Transport Services (EFTS).
Under climate change, the association of HR days with hot weather became more obvious in recent years. Prolonged hot weather condition favours the formation of ozone in the South China that attributed to most of the PHR in HR days in Hong Kong.
We appreciate that the policies, legislations and measures having undertaken by the Administration improved the local air quality significantly. However, district concerns, especially for NDAs, and effect of climate change on air quality are still outstanding. The Administration should focus on reducing the precursors of ozone, i.e. nitrogen dioxide and volatile organic compounds, and combating the physical conditions in favour of ozone formation, e.g. prolonged hot and dry weather.
For any queries, please contact the undersigned at Green Power (T: 3961 0200, Fax: 2314 2661, Email: info@greenpower.org.hk)
Thank you very much for your kind attention. I look forward to the Administration’s policies to further relieve the health risk of the public associated with air quality.
Yours faithfully,
CHENG Luk Ki
Director,
GREEN POWER
Yours faithfully,
CHENG Luk Ki
Director,
GREEN POWER
Encl.
A Brief Review of AQHI Data of Hong Kong for 2025
