'Covid Brings Cleaner Air But Govt Not Doing Enough'

A green group said on Thursday that despite improvements in air quality amid Covid-19 outbreaks last year, pollution levels are still far exceeding the limits set by the government.

Clean Air Network analysed data collected from both general and roadside monitoring stations set up by the government across the city, and found that levels of major pollutants declined by 13 to 24 percent compared to those in 2019.

The group said the improvement was partly due to social-distancing measures like working-from-home policies which reduced traffic.

But the average annual nitrogen dioxide (NO2) concentration level almost doubled the limits in the local Air Quality Objectives (AQO) and World Health Organisation (WHO) guidelines at all three roadside monitoring stations, in Causeway Bay, Central and Mong Kok.

The annual averages for general stations, meanwhile, were below the limits.

As for ozone, the main ingredient in "smog", the group said the annual average was also alarming, as it stayed at record high levels.

The AQO states that ozone concentration should not exeed the limit for more than nine times a year, but at five New Territories monitoring stations, the level was higher than the limit on 10 to 17 occasions.

The network said pollution caused by PM particles was less serious, but the levels only met local objectives, not the more stringent WHO standards.

The group said the improvement of roadside pollution was limited, but "levels of ozone and NO2 were still alarming and more effort should be paid on lowering their concentrations."

Clean Air Network said to better control air pollution, the government needs to have an ambitious roadmap to change the local fleet of franchise buses, strengthen control over ozone, and extend low emission zones to cover highly polluted areas such as Sham Shui Po, Tuen Mun and Kwai Chung.