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Letter to the Editor of the South China Morning Post dated 1 April, 2005 - Response to the letter headlined "Air quality limits obsolete and harmful"
I refer to the letter headlined "Air quality limits obsolete and harmful" published on March 31.
On setting air quality standards and objectives, ideally, the lower the concentration of air pollutants, the better. However, there are no standards applicable to all countries and places. The Air Quality Guidelines for Europe published by the World Health Organisation (WHO) has pointed out that considerations such as the prevailing exposure levels, technical feasibility, source control measures, abatement strategies, and social, economic and cultural conditions should be taken into account when setting air quality standards for a particular place.
The Air Quality Objectives (AQOs) adopted by Hong Kong have been developed with reference mainly to researches in the United States (US) and the situation in Hong Kong. They were derived from scientific analyses of the relationship between pollutant concentrations in the air and the associated adverse effects of the polluted air on the health of the public.
We cannot compare the standards of two places by simply looking at the limit values. The EU's air quality standards allow for multiple exceedances: the hourly average sulphur dioxide (SO2) standard can be exceeded 24 times a year, whereas only 3 times a year are allowed in Hong Kong. For Respirable Suspended Particulates (RSP), the EU allows the daily average RSP standard to be exceeded 35 days in a year, whereas the relevant AQO of Hong Kong does not allow more than a single day of exceedance in a year.
The Environmental Protection Department (EPD) has all along been closely monitoring the researches and reviews on air quality standards conducted by different places. We will make reference to the latest international standards and practices, in particular those of the EU and the US, as well as the on-going local studies, when considering the need for revising Hong Kong's AQOs from a scientific perspective and the local applicability of the revised AQOs.
The Government is determined to improve the air quality and protect the health of the public. Strong actions have been taken to improve both the roadside air quality and regional air quality.
The EPD has implemented a comprehensive control programme to reduce roadside vehicle emissions. The programme includes switching to LPG taxi, replacing diesel light buses with LPG/electric vehicles, adopting the most stringent Euro III emission standards, using ultra low sulphur diesel, retrofitting particulate trap/catalyst to old diesel vehicles, strengthening emission tests and enforcement against smoky vehicles, etc. These initiatives have already proven to be effective. Compared with 1999, the number of smoky vehicles dropped by around 80% in 2004. RSP and NOx at roadside dropped by 9% and 24% respectively.
On regional air pollution, the HKSAR Government and Guangdong Provincial Government have agreed to aim to cut the emissions of sulphur dioxide, nitrogen oxides, respirable suspended particulates and volatile organic compounds by 40%, 20%, 55% and 55%, respectively, using 1997 as the base year, and strive to achieve those targets by 2010. Achieving these targets will not only enable Hong Kong to meet its current AQOs but also significantly improve the air quality of the PRD and relieve the regional smog problem.
Tse Chin Wan
Assistant Director (Air Policy)
for Director of Environmental Protection
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