Stubborn roadside pollutant on rise again in Hong Kong after three years of decline, group says
NO2 readings last year serious enough to be observed inside homes and buses
Concentrations of a stubborn roadside pollutant intensified in Hong Kong last year, reversing three years of decline and casting doubt on the government’s ability to meet its air quality targets for 2020.
Nitrogen dioxide (NO2) levels were serious enough in western parts of the city that unsafe measurements were observed inside homes and even buses, the environmental group Clean Air Network found.
The group’s latest review of the city’s air showed average annual NO2 concentrations measured at the government’s three roadside air quality monitoring stations had risen from about 82 micrograms per cubic metre of air in 2016 to 85mcg last year.
That was despite roadside NO2 levels falling steadily since 2013 and the Environmental Protection Department last year projecting the figures would dip below 80mcg by 2018 and hit 65mcg by 2020.
The group was now “pessimistic” about hitting those targets.
In Causeway Bay, average annual concentrations were 9.5 per cent higher than in 2016, while Central and Mong Kok tallied rises of 4.4 and 4.0 per cent respectively.
The results indicated a “clear deterioration in roadside air quality”, the group’s community relations manager Loong Sze-wai said.
“In terms of [ambient air], NO2 pollution was concentrated in western parts of Hong Kong … and highest in Kwai Chung, Sham Shui Po and Tsuen Wan,” Loong said. “Concentrations were mostly higher than the World Health Organisation’s annual safe level of 40mcg.”
Concentrations of PM2.5 – hazardous microscopic particles suspended in air – were also up slightly at the stations.
The department maintains a network of three roadside monitoring stations and 13 ambient air monitoring stations, which are placed higher above ground.
Loong attributed the worsening air quality to high and increasing traffic density in these neighbourhoods as well as an ageing, expanding vehicle fleet.
According to public data from the University of Hong Kong’s Hedley Environmental Index, there were an estimated 1,849 air pollution-related non-accidental premature deaths last year – 300 more than in 2016 – and about 430,000 more doctor’s visits.
Based on WHO research and previous scientific studies, the Clean Action Network estimated the NO2 and PM2.5 levels last year increased the risk of mortality by 17.6 and 9.8 per cent.
The group also carried out a month-long pilot study between November and December to monitor residents’ exposure to NO2 in their daily lives. In the study, six volunteers living in relatively polluted districts carried around mobile NO2 sensors.
It found that NO2 levels during commutes were two to three times as high as levels recorded at their corresponding ambient air monitoring station, especially in the city’s western districts.
A Yuen Long resident measured NO2 concentrations as high as 82.8mcg in his flat. That was about twice as high as the reading at the nearby Yuen Long monitoring station and the WHO’s annual safe level of 40.
Another participant discovered she was exposed to average NO2 concentrations as high as 90.4, during her daily commute to work on KMB route 269D, which runs through highly polluted districts including Yuen Long.
“We are not looking seriously enough at the risks of air pollution exposure in the community,” Loong said.
“We may feel we are on a bus, it’s enclosed and there’s air conditioning so the air should be fine. But these cases show the health risks can be high. Some routes pass through heavily trafficked roads.”
Loong added that most buses operating on routes outside low-emission zones were older, more polluting models.
The group’s CEO, Patrick Fung Kin-wai, said officials were not doing enough to tackle air pollution as a health risk and called for revised air pollution laws that would hold principal officials accountable for failing to meet targets.
“There is no political will … for the transport, health and environment bureaus to work closely together,” he said. “Tackling the problem requires high-level intervention, led by Chief Executive Carrie Lam Cheng Yuet-ngor.”
During her campaign for the city’s top job, Lam, pledged in her policy manifesto to “ensure coordination” among government bodies to improve air quality and “strive to reduce air pollutants” and control emissions.
An Environmental Protection Department spokesman said roadside NO2 posed a challenge for many large cities and that “meteorological conditions” could have caused the recent “fluctuation” locally.
“We should not only look at short-term changes of one to two years, but also observe long-term annual average trends in pollutants,” he added.
The department said it would review codes on air pollution control at public transport interchanges, which had not been updated for decades.