Local air quality has hit prolonged unhealthy levels amid winter smog

An IQAir map showing widespread unhealthy to hazardous air quality across parts of East and South Asia, with heavy pollution concentrated over mainland China

Macau’s air quality reached “unhealthy” levels this week, with a leading local environmental advocate warning that the city is suffering its “longest continuing bad air quality duration” in recent years and is lagging behind regional peers in cutting pollution.

According to real-time data from IQAir, Macau’s air quality index stood at a high 191 on Tuesday, a level classified as “unhealthy,” with fine particulate matter PM2.5 measured at 106 micrograms per cubic meter. Other pollutants, including PM10, were recorded in Macau on Tuesday at 158.5 µg/m³, ozone at 194.3 µg/m³, nitrogen dioxide at 107.1 µg/m³, sulphur dioxide at 5.6 µg/m³, and carbon monoxide at 952 µg/m³.

Comparatively, IQAir air quality maps show major mainland cities in the South – including Guangzhou, Foshan, Dongguan, and Jiangmen – are also grappling with “unhealthy” to “very unhealthy” levels this winter.

According to environmental data trackers, winter air pollution across China largely arises from ramped-up emissions during the winter season from heating, compounded by adverse weather.

Coal- and biomass-fired residential heating in China’s northern areas pumps out heavy particulate matter and sulfur dioxide, while power plants, steel mills, cement factories, and chemical plants add to the mix.

In addition, open-air burning of biomass and crop straw in rural areas further exacerbates the problem.

China has made progress through clean-air policies, such as the heating initiative targeting severe winter smog in northern cities in 2017.

However, the relocation of heavy industry to less-regulated areas continues to hinder gains, leaving persistent haze in places like the Pearl River Delta.

Temperature inversions, shallow boundary layers, weak winds, and high humidity trap pollutants near the ground during Macau’s winter months, which consequently accelerates secondary aerosol formation from precursors such as sulphur dioxide, nitrogen oxides, ammonia, and volatile organic compounds.

Meanwhile, a Macau-born environmentalist and educator pointed to unusually high winter temperatures and temperature inversions as reasons for trapping pollutants in the city’s dense concrete landscape.

“This year we are suffering from the longest continuing bad air quality duration,” Joe Chan, chairman of the Macau Green Student Union and vice-chairman of Green Future. told the Times.

“This year we are experiencing unusually high temperatures during winter,” he said, adding that “high temperatures and high UV levels trigger more reactions of pollutants (mainly NOx) from the vehicles. It’s called photochemical smog, which worsens the air quality.”

Regarding PM2.5, which refers to fine inhalable airborne particles with diameters of 2.5 micrometers or smaller, Chan said these levels have stayed “quite stable” over the past 10 years. “If you compare the level of our regional city, we are falling behind, since PM2.5 can be effectively controlled by improving the public transport system and cutting heavily polluting vehicles,” the environmentalist noted.

However, he pointed to Macau’s inability to improve public transport or scrap polluting vehicles amid rising car density and traffic jams, stating, “In fact, these two things Macau is not doing to their best,” he said.

“The rising density of vehicles, even though we have increased the electric vehicle percentage, causes more traffic jams on the road. Stuck vehicles cannot combust fossil fuels efficiently.”

Simultaneously, he pointed to the renewal rate of old tourist buses and construction trucks as being “incredibly low” (insufficient combustion creates more air pollutants).

Macau’s air quality reaching an unhealthy level on Tuesday, with index peaking at 191

On phasing out old fleets, Chan recommended timelines based on vehicle age, noting maintenance costs exceed new purchases after eight years. “I suggest the subsidy level should be at least 10 to 15% of the depreciation of the vehicle, or the penalty cost for polluting vehicles on the road should be increased,” he advised, mirroring Singapore’s Early Turnover Scheme.

He also advised short-term action like frequent monitoring of “octopus vehicles” by the Environmental Protection Bureau (DSPA) and imposing engine cut-off rules in idling zones, as they do in Hong Kong. “In Hong Kong, there are some areas where it is required to turn off engines when cars are not moving in order to reduce air pollution to the public… but sadly in Macau, there is no such legislation,” explained Chan.

For crowded areas with narrow streets and poor ventilation, he suggested restricting access to electric vehicles or public transport only.

“To improve the air quality in that region (narrow streets with poor ventilation), pollutants are easily trapped and this hazards our citizens and tourists’ health, which also ruins the reputation of our city,” Chan said.

Health impacts are rising

The Health Bureau (SSM) recorded 2,515 asthma patients in 2022, or 0.4% of the population, with the 60-74 age group at 25.6%, the highest share.

The Times contacted the SSM for updated statistics on asthma registration, but had not received a reply as of press time.