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Letter to the Editor of the Sunday Times dated 11 November , 2004 - Response to Greenpeace claims about Hong Kong's AQO and API
Greenpeace claims (Sunday Times, November 7) about Hong Kong's Air Quality Objectives (AQO) and Air Pollution Index (API) are unscientific and unfounded. Hong Kong's AQO are in general similar to those of the United States.
The methodology and API values are basically adopted from the Pollutant Standards Index (PSI) system of the United States, and are similar to those used in Singapore and Taipei.
Greenpeace has applied indiscriminately the guideline levels of the World Health Organisation (WHO) or the air quality standards of the European Union (EU) in working out an API of their own.
The WHO and the EU have not set any standard for computing API. Both the WHO guideline levels and the EU air quality standards are not amenable to being adopted in an API system for Hong Kong.
The WHO has not laid down any guideline level for respirable suspended particulates (RSP) or PM10, missing out a key pollutant of concern. The EU's air quality standards allow for frequent excesses, making it impossible to make direct comparison with Hong Kong's AQO. For example, the EU allows the daily average RSP standard to be exceeded for 35 days in a year, whereas Hong Kong considers it failing the objective if the standard is exceeded for more than once.
We should be most grateful if you would publish the above facts so that your readers could have a better understanding of Hong Kong's AQO and API, and would not be misled by the unfounded claims of Greenpeace.
Mr Robert J S LAW
Director of Environmental Protection
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