XN000022-1995-12-12 — Page 24

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Air Quality Report for November

**

The Environmental Protection Department today (Tuesday) released air quality information for November.

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 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 November, there were no exceedances of the 24-hour Air Quality Objective (AQO) values at any of the three sites. Mong Kok station recorded the highest concentration of air pollutants, with the 24-hour average NO2 slightly more than 90 per cent of the corresponding AQO on November 22.

Throughout the month, Hong Kong was mainly affected by the dry continental air stream from the northeast, resulting in higher dust levels. But the dust levels were still within the 24-hour AQO.

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.