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Harmful ozone levels in Hong Kong up 35pc in last 15 years

Concentrations of ozone in the city’s air have increased by a third in the last 15 years, highlighting yet again the severity in regional air pollution, according to government data.

Between 1999 and last year, concentrations of ambient ozone at the city’s general air quality monitoring stations rose by 35 per cent, despite levels of all other pollutants showing decreases.

Preliminary data released by the Environmental Protection Department today recorded ozone concentrations at general stations increasing by 7 per cent from 43 micrograms per cubic metre to 46 micrograms per cubic metre last year.

“This once again shows more needs to be done in terms of cooperation with the region,” said Mok Kwai-cheung, the department’s assistant director of environmental protection.

Ozone is a major component of photochemical smog that reduces visibility and threatens human health when exposure is prolonged and high.

The pollutant is formed by a reaction between volatile organic compounds (VOCs) and nitrogen oxide (NOx) generated from other combustion sources. The dirty, orange smog enveloping views of the harbour on heavily polluted days is created when these two pollutants react with sunlight.

Hong Kong has set a target to reduce NOx by 20 to 30 per cent and VOCs by 15 per cent by 2020 in accordance with a regional air quality management plan between the city and Guangdong.

A cross-border study funded by the department last year found that nearly half of the ambient VOC levels in the Pearl River Delta region were traffic-related, with petrol exhaust the biggest single contributor.

The report suggested that reducing traffic in the delta region by half could be one of the most effective means of combatting regional smog. But cutting VOC emissions from traffic by half could achieve the same effect.
Source URL (modified on Feb 24th 2015, 6:52pm):

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