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Air quality report for February
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The Environmental Protection Department today (Monday) released air quality information for last month.
The purpose of the announcement is to keep the public informed of the air quality levels in the territory and to explain the measurements.
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 mentioned. 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.
In February, no exceedances of the 24-hour Air Quality Objectives were measured at any of the three stations. As usual, levels of pollutants were highest at the street-level site of Mong Kok.
The highest levels of the pollutants NO2 and S02 were measured on February 9, 12 and 13. These peaks were caused by low wind speeds which prevented locally produced pollutants from being blown away. Dust levels also peaked on those three days.
The gases and particles described originated from various sources. S02 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.
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