Asian countries have the worst air quality in the world, study finds

Less than one per cent of the world’s population breathes pollution-free air – and Asian countries face some of the most severe health risks, according to a new study.

About 99.82 per cent of the global land area is exposed to dangerous levels of particulate matter 2.5 (PM2.5) that are above the safety limit recommended by the World Health Organisation (WHO), according to the research published in Lancet Planetary Health.

Only 0.001 per cent of the world’s population breathes air considered acceptable, it found.

PM2.5 are tiny particles in the air that have been linked to serious illnesses such as lung cancer and heart disease.

The study, conducted by scientists in Australia and China, used more than 5,000 monitoring stations worldwide and machine learning simulations, meteorological data and geographical factors to estimate global daily PM2.5 concentrations.

They found that on a global level, more than 70 per cent of days in 2019 had daily PM2.5 concentrations exceeding 15 micrograms of gaseous pollutants per cubic metre, the WHO-recommended daily limit.

The study found that air quality is particularly worrisome in regions such as south Asia and east Asia, where more than 90 per cent of days had PM2.5 concentrations above the 15 microgram threshold.

Fine particulate matter is made up of soot from vehicles, smoke and ash from wildfires, and biomass cook-stove pollution, plus sulfate aerosols from power generation and desert dust.

Short-term exposure, particularly a sudden increase, to PM2.5 is a leading contributor to the global burden of diseases and mortality, the study notes. However, there haven’t been many studies showing how PM2.5 levels have changed over time and across the world over recent decades.

“I hope our study can change the minds of scientists and policymakers for the daily PM2.5 exposure. If we can make every day with clean air, of course, the long-term exposure of air pollution would be improved,” said Yuming Guo, lead researcher and environmental health professor at Monash University.

The researchers also examined how air pollution changed over the two decades up to 2019.

For instance, most areas in Asia, northern and sub-Saharan Africa, Oceania, Latin America and the Caribbean experienced an increase in PM2.5 concentrations over 20 years, driven in part by intensified wildfires.

Annual PM2.5 concentrations and high PM2.5 days in Europe and northern America has decreased over time, the study noted, thanks to stricter regulations.

It found that the highest concentrations of PM2.5 occurred in east Asia, at 50 micrograms per cubic meter, followed by south Asia at 37 micrograms and North Africa at 30 micrograms.

In contrast, residents of Australia and New Zealand faced the least threat from fine particulate matter, while other regions in Oceania and southern America were also among the places with the lowest annual PM2.5 concentrations.