A weekend lost to the haze, and there's more to come
Environment chief challenged over worsening air quality
High levels of pollution that plagued Hong Kong over the weekend would remain for a few more days, the Observatory said, adding that the decline in air quality had been caused by a high-pressure weather system.
The environment minister yesterday attributed the serious pollution to a regional influence from the Pearl River Delta, but atmospheric experts said roadside pollution had also contributed to worsening air quality.
One expert said a study had found that blue skies earlier this summer were the result of high wind speeds caused by an abnormal change in regional weather patterns, and questioned the minister's earlier claim that the blue skies were a beneficial result of government anti-pollution efforts.
The roadside air pollution index reached the 'very high' level, climbing to 143 in Central, 128 in Causeway Bay and 134 in Mong Kok yesterday.
Pollution levels in other districts ranged from 88 to 127.
Tam Cheuk-ming, senior scientific officer at the Observatory, said a ridge of high pressure in southern China had reduced wind speeds in Hong Kong to about 2 to 12 km/h, adding that air pollutants could not be dispersed when there were low wind speeds. The Observatory expects the low wind speeds to remain for a few more days, with winds picking up after Thursday.
Environment Secretary Edward Yau Tang-wah said earlier that blue skies this summer had shown government measures were effective. He said air quality in Hong Kong was reduced by industrial emissions on the mainland but Guangdong officials were tackling the problem.
However, Alexis Lau Kai-hon, an atmospheric scientist from the University of Science and Technology, said pollution levels recorded in other districts were generally lower than the roadside levels in Central, Causeway Bay and Mong Kok, showing local vehicle emissions also contributed to high air pollution days.
'It would be unfair if we blame the problem solely on the mainland,' he said, adding that the blue skies that appeared this summer might not be simply the result of government efforts. Mr Lau found that the average wind speed in Hong Kong this summer had been exceptionally high - about 2 metres a second higher than the average wind speed over the past 30 years.
He said the high wind speeds were caused by an abnormal change in regional weather patterns, which might be a possible symptom of climate change. He added that the wind speeds in Beijing, on the other hand, were exceptionally low this summer.
David Hui Shu-cheong, head of respiratory medicine at Chinese University, said drastic measures should be taken to protect vulnerable people from bad air. He said studies found an increase in ozone of 10 micrograms per cubic metre would raise the overall risk of hospital admissions from asthma by about 3 per cent.
