Hong Kong's roadside air pollution reached life-threatening levels one in every eight days last year, a report said Monday, citing figures obtained from the government.
The roadside air pollution index recorded by the Environmental Protection Department showed there were 44 days of "very high pollution" in the Central district last year, the South China Morning Post said.
The figure was significantly higher than 39 days in 2008 and 13 days in 2005, the newspaper said.
"Very high pollution" levels -- with the air pollution index exceeding 100 -- can significantly aggravate the symptoms of people with heart or respiratory illness, the department said.
Healthy people may experience irritation to the eyes, wheezing, coughing and sore throats.
A roadside station in the densely-populated Mongkok district recorded 37 "very high pollution" days last year, compared to just one five years ago, the report said.
In Causeway Bay, another busy shopping and residential hub, the figure is up five-fold from 2005, reaching 25 days, the report said.
A department spokesman said the trend could be partly attributed to unfavourable weather conditions and that the index did not reflect the full picture.
"Selective picking of a certain range of Air Pollution Index readings for comparison will not give a fair and comprehensive picture of how air quality changes over the years," a department spokesman said in a written reply to AFP.
However, a team of scientists said findings from their own research show that the roadside pollutant levels in Central were two or three times higher than the government figures.
"From the findings of our study, we can logically deduce that the number of 'very high pollution' days would be more than the (government's) figure," said team leader Chak Chan, acting head of the environment division at Hong Kong University of Science and Technology.
Chan said their findings were more accurate because they used mobile measuring devices, while the government used stationary tools.
Air quality in Hong Kong continues to deteriorate due to emissions from the southern Chinese factory belt over Hong Kong's northern border and local emissions from power generators and transport.
The city has been wrapped in a thick blanket of haze for most days in recent months.
Explore further: Hong Kong air pollution equals record high