LCQ17: Government studies the PM 2.5 air quality standard development

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Following is a question by the Hon. Martin Lee and a written reply by the Acting Secretary for the Environment and Food, Mr Paul Tang, in the Legislative Council today (May 17).

Question :

At present, the "respirable suspended particulates" concentration, in respect of which an air quality objective has been set, is measured by the weight of particulates with an aerodynamic diameter of less than 10 micrometres (known as "PM10") in every cubic metre of air. In view of the fact that the smaller the size of a particulate is, the greater impact it has on human health, the U.S. Environmental Protection Agency ("EPA") introduced air quality standard for PM2.5 in 1997. In this connection, will the Government inform this Council:

(a) in regard to each of the districts in the territory, of the respective numbers of days since 1998 on which the 24-hour average PM2.5 pollutant concentration in the air exceeded the standard established by the EPA;

(b) whether the Environmental Protection Department has plans to commission a consultancy study on the source of PM2.5 pollutants in the territory; if it has, of the details and the timetable; and

Reply :

The Government has been studying the development of air quality standards for PM2.5 (particulates of aerodynamic diameter less than 2.5 micrometres) both in the United States (US) and in the European Union (EU).

In July 1997 the US published a standard for PM2.5. However, the basis for and the appropriateness of this standard have been challenged in the US courts. As a result, the United States Environmental Protection Agency (USEPA) is currently reviewing the standard. The current schedule is that a final decision on whether to retain or revise the standards for particulate matters will be made in July 2002. This is an overall review of the national ambient air quality standards of the US and the standard for PM2.5 will be reviewed along with other potential indicators for particulate matters.

The EU is also considering a standard for PM2.5 and has adopted a timetable to complete the review by the end of 2003.

The Environmental Protection Department (EPD) has been considering a programme on PM2.5 standard for Hong Kong. It has carried out studies to develop local PM2.5 monitoring capability and is studying whether the US or the EU monitoring protocol is more appropriate for Hong Kong.

Our replies to the specific question are as follows:

(a) Comparison with the PM2.5 standard proposed by the USEPA requires 3 years continuous data before an assessment can be made. There are not yet sufficient data for an assessment of Hong Kong's PM2.5 levels on this basis. Even under the original schedule in the US (which has not been confirmed yet for the reasons mentioned above), the assessment would not be completed until 2003 to 2004.

(b) EPD has no plan to commission a study on the source of PM2.5 in the immediate future. We know that PM2.5 is a major component of respirable suspended particulates (RSP) and that generally both have the same sources, such as motor vehicle emissions and other fuel combustion. The need for further detailed studies into the sources of PM2.5 would depend on the development of approaches to PM2.5 internationally.

(c) EPD fully recognizes the significance of PM2.5 in air quality monitoring and public health. We will take into full consideration the overseas review results and both local and overseas medical information when deciding whether an air quality objective for PM2.5 should be introduced. In the interim, the measures being taken to reduce local RSP levels are expected to contribute to reducing PM2.5 levels. The monitoring project of PM2.5 that is being carried out should enable us to observe changes and help develop additional control measures if required.

End/Wednesday, May 17, 2000

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