But the worsened air pollution last year was estimated to have led to 1,329 premature deaths and a total economic loss of HK$15.8 billion, Clean Air Network found after analyzing the air quality data released by the Environmental Protection Department.

For the first time after Covid broke out in Hong Kong in January 2020, the group found the levels of all four major air pollutants -- nitrogen dioxide, respirable suspended particulates, fine suspended particulates and ozone -- had risen last year.

he worst air quality was recorded in Kwai Chung and Tuen Mun. Among them, the level of nitrogen dioxide last year was 37 milligrams per square meter of air, 12 percent more than 33 milligram per square meter of air in 2020.

The network said although in 2019 the figure was 38 milligrams before the pandemic emerged, and the SAR’s Air Quality Objectives annual concentration limit for nitrogen dioxide -- newly added to the list last year -- was 40 milligrams, the figure last year at 37 milligrams was still 3.7 times of that of the World Health Organization’s standard at 10 milligrams.

The level of nitrogen dioxide by roadside detectors were as much as 72 milligrams per square meter, which is more than seven times of the WHO standard.

Another pollutant ozone has also recorded a significant increase, with the general concentration being 57 milligrams per square meter, 10 percent more than 52 in 2020.

The ozone concentration recorded by Tap Mun air Quality Monitoring Station was 77 milligrams. The general reading last year was the second highest in 20 years, after 60 milligrams in 2019.

The third major pollutant is respirable suspended particulates, which general reading was 28 milligrams per square meter, comparing with 26 in 2020. The roadside reading was 34 last year, also higher than 32 in 2020.

The last pollutant is fine suspended particulates, which general and roadside readings were 16 and 21 last year respectively, comparing with 15 and 19 in 2020.

“As the Covid pandemic broke out in 2020, transportation was reduced because of social distancing measures such as suspension of classes and remote working, resulting in a drop in the level of air pollution,” the group said.

“In 2021, as those measures were relaxed, the level of air pollution bounced back, though yet to reach that in 2019 before the pandemic. However, if the government does not take immediate action to curb such rising trend, public health will be under threat.”

The group cited the University of Hong Kong’s School of Public Health that last year, the adverse health impact brought by air pollution had led to a total of 1.69 million doctor visits, 98,451 hospital bed days and 1,329 premature deaths, comparing with 1.6 million, 93,991 and 1,268 in the year 2020 respectively.

A total economic loss of HK$15.8 billion had been inflicted, more than HK$15 billion in 2020.

According to the WHO, exposure to high levels of air pollution can cause a variety of adverse health outcomes, such as increased risk of respiratory infections, heart disease and lung cancer.

The group suggested authorities to speed up full adoption of zero emission in commercial vehicles, as buses, trucks, minibuses and taxis only account for 20 percent of the city’s vehicles, but contributed to over 90 percent of total emission of nitrogen dioxide in Hong Kong.

To lower the level of ozone concentration, authorities must find out the origins of ozone and outline action plans to reduce such levels.