Delta air cleaner, roadside air worse

Environment officials have been told not to rejoice over remarkable improvements in regional air quality last year, since roadside air pollution continues to worsen and remains at health-threatening levels.

Hong Kong and Guangdong yesterday jointly released monitoring results that showed sulphur dioxide and nitrogen dioxide levels fell 26 and 7 per cent respectively last year, some of the biggest reductions recorded in four years.

But roadside figures quietly published on the government website two days ago showed annual average concentrations of nitrogen dioxide at the roadside in Causeway Bay, Central and Mong Kok all rose by up to 13 per cent.

The figures, the worst in at least five years, show concentrations of the key pollutant exceeded 100 micrograms per cubic metre of air - more than double the World Health Organisation guideline of 40.

The Clean Air Network, an independent group that encourages public comment about air pollution, said officials would be 'grossly disingenuous and misleading' if they were to call the regional improvement a victory, as many people were still being exposed to excessive local pollution.

'Roadside pollutant concentrations are critical when assessing harm to human health,' network chief executive Joanne Ooi said. 'What matters is the level of pollution to which people are actually exposed to at street level.' She noted that all the regional monitoring stations were well above that level.