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Air Quality Report for March
The Environmental Protection Department today (Thursday) released air quality information for March.
The announcement contains monitoring results from Mong Kok, Central/Western and Kwai Chung, which represent three important land use types in the territory:
locations close to road traffic in built-up urban areas;
combined commercial and residential districts; and
districts close to industrial areas.
The department currently monitors air quality continuously at eight stations, including the three above mentioned districts. Short-term measurement exercises are also undertaken as and where the need arises.
The reported air pollutants include sulphur dioxide (SO2), nitrogen dioxide (NO2), total suspended particulates (TSP) which comprise all sizes of dust particles, and the respirable fraction of the dust (RSP). All these pollutants can affect respiratory health in sufficient concentration.
Levels of air pollution had great variation in March and there were several exceedances of the 24 hour Air Quality Objectives.
On March 13, the TSP and RSP limits were exceeded at Mong Kok monitoring station and the RSP limit was breached at Central/Western monitoring station. On March 22, the NO2 limit was exceeded at Central/Western while levels of NO2 were also high at the other two stations.
The gases and particles described originated from various sources. SO2 is mostly produced when fuels that contain sulphur are burned. NO2 is formed during combustion by the combination of nitrogen and oxygen, and by the atmospheric oxidation of nitric oxide (NO), also a product of combustion.
Vehicle exhaust is an important source of NO and NO2 in terms of impact on local air quality. It is also a major source of airborne particulate matter, especially the smaller respirable particles.
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