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Air quality objectives 'will make things worse'

The government's proposed air quality objectives would actually make some pollution worse, University of Hong Kong researchers say.

Using a new mathematical model that predicts pollutant levels over a year's time, the researchers found sulphur dioxide would rise sharply over 2010 levels if the government's proposed objectives were adopted.

According to the model, the more stringent the legal limit of a pollutant, the less that pollutant will occur in the air. Academics from the university's school of public health used the model to predict the levels of five pollutants. Their research was published in the Open Epidemiology Journal.

If Hong Kong adopted the government's proposed objectives, the annual mean maximum level of sulphur dioxide would be 42 micrograms per cubic metre, compared with 26 last year.

It would also yield an annual mean maximum of 35 micrograms per cubic metre for fine particulate PM2.5, whereas the 2010 level was 33.

The researchers said Hong Kong should instead follow the objectives laid down by the World Health Organisation. Those would cut the mean maximum level of sulphur dioxide and fine particulate PM2.5 to 5 and 10, respectively.

'Even though the government's proposed objectives looked similar to that of the WHO, it is in fact misleading and cannot improve air quality,' said honorary assistant professor Dr Lai Hak-kan, who led the study.

If Hong Kong adopted the WHO's objectives, there would be about four million doctor visits and 68,000 hospital admissions a year due to poor air quality. But if it adopted the government standards, the figures would rise to five million and 92,700, respectively, researchers said.

They found that if the city adopted the proposed objectives, the general levels of particulates would not meet the WHO standard until 2529.

Lai said the proposed objectives would decrease the levels of particulate PM10 from 180 to 100. But that was just on par with objectives India set out 15 years ago.

An Environmental Protection Department spokesman said the objectives were similar to those of the EU and US, but 'regional influences' made it impossible to set a higher objective for PM2.5 and PM10 levels.

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