Response to Severe Air Pollution Episode

Hong Kong–Clean Air Network (‘CAN’) is concerned with the severe air pollution episode ongoing in Hong Kong, because it affects the health of the general public, especially children, whose respiratory, circulatory and immune systems are still developing. We call for the continuous monitoring of indoor air quality at all public spaces, including locations frequented by children and the extension of existing government guidelines on student activity under air pollution to child care centres, in response to this and future similar pollution episodes.

Since Saturday, there has been a significant increase in air pollution levels, particularly respirable fine particulates (PM10) levels, in Hong Kong. The Air Quality Health Index (‘AQHI’) reached the worst level, ‘serious’/10, in Tuen Mun and ‘very high’/8-9 in some other districts.

While the Government collects data on ambient and roadside air quality at 15 general monitoring stations and three roadside stations, there is no systematic collection of indoor air quality data in Hong Kong, although the public, especially students, spend most of their time indoors. CAN has been monitoring air quality at four secondary schools on a continuous basis as part of our new Indoor Air Quality Research Project,to fill this data gap. Two of the schools are located in Kwun Tong, one in Tai Kok Tsui and one in Tsuen Wan. The particulate matter (PM) levels on 13 April (Sunday) (daily averages) exceeding Hong Kong’s statutory air quality objectives are stated below:

Recommendations

In addition to the immediate mitigation measures for children, elderly, chronic patients and outdoor workers, CAN makes the following medium and long term recommendations to safeguard public health:  

Monitoring indoor air quality continuously and taking improvement measures at schools, kindergartens and child care centres

When ambient PM levels are high, indoor PM levels are likely to rise correspondingly. The Government should encourage and subsidise child care centres, kindergartens, primary and secondary schools to install continuous indoor air quality monitors and take improvement measures including using air purifiers when PM concentrations exceed the above-mentioned air quality objectives. 

For comparison, in South Korea, the School Health Act requires schools to install a PM2.5 measuring device and air purifiers in each classroom.

Extending government guidelines to child care centres

The guidelines for kindergartens, primary and secondary schools on student activity under severe air pollution do not apply to child care centres. We recommend that the Social Welfare Department develop similar guidelines for child care centres.

Background Information

New statutory air quality objectives for ambient air came into effect on 11 April 2025. The new objective for PM2.5 (daily average) is 37.5µg/m3 and the one for PM10 (daily average) is 75µg/m3. In the absence of statutory indoor air quality objectives in Hong Kong, we apply these objectives to indoor air, as the World Health Organization has pointed out that there is no convincing evidence of a difference in the health risk of PM outdoors and indoors. 

The Education Bureau is responsible for the licensing of kindergartens, primary and secondary schools, while the Social Welfare Department is responsible for child care centres. The guidelines issued by the Education Bureau do not apply to child care centres.

Further information about legislation on indoor air quality in other jurisdictions, namely France, Korea and Taiwan, can be found on CAN’s Indoor Air Quality Information Hub.

14 April 2025