Almost nobody on Earth is safe from air pollution, study says

Nearly the entire global population is regularly exposed to unsafe levels of air pollution, according to a study published this week.

Researchers at Monash University in Australia analyzed air pollution data from across the globe between 2000 and 2019 to estimate global daily exposure to PM 2.5, a type of air pollution made up of inhalable particles 2.5 micrometers or smaller. The particles can enter the bloodstream through the lungs and contribute to an array of health problems, including premature death, asthma, and heart disease.

The team found that between 2000-2019, only 0.18% of the world’s land area and only 0.001% of the world’s population — about 78,000 people — had annual PM 2.5 exposure lower than the 2021 air pollution guidelines set by the World Health Organization (WHO). The WHO’s guidelines recommend that a person’s annual exposure to PM2.5 should not exceed 5 micrograms per cubic meter.

“Almost no one is safe from air pollution,” said Yuming Guo, an author on the study and a professor of environmental health at Monash University. “All people might face serious air pollution.”

The new findings come as the United States and countries around the world are wrestling with how to regulate harmful air pollution, which was estimated to cause almost 7 million premature deaths in 2019,  according to one study. The Environmental Protection Agency (EPA) recently proposed lowering its standards for annual exposure to PM2.5 from the current standard of 12 micrograms per cubic meter to between 9 and 10 micrograms per cubic meter, a measurement it said reflects “the latest health data and scientific evidence.”

The EPA estimates that setting the PM2.5 standard at a level of 9 micrograms per cubic meter could prevent up to 4,200 premature deaths per year. But many scientists say the proposal doesn’t go far enough to protect public health.

The researchers on the new study had expected to find some parts of the globe to have very clean air, and were surprised when their analysis showed that nearly everywhere on earth experiences high levels of air pollution at some points during the year, Guo said.

The team used data from 5446 monitoring stations across 65 countries, then used machine learning to estimate the air pollution in areas without monitoring stations. A lack of monitoring stations in some countries was the biggest limitation to the study, said Guo. More accurate modeling of global air pollution would be possible with more air monitoring stations worldwide, he said.

The results of the study varied geographically. The highest PM2.5 concentrations were found in eastern and southern Asia, followed by northern Africa, while the lowest PM2.5 concentrations were found in Australia, New Zealand, and other regions in Oceania. Results also varied seasonally, with an increase in PM2.5 in Asia and Africa in the winter months and higher air pollution in the Americas during the summer.

The differences in air pollution measurements are driven by differences in pollution sources, according to Guo. The sources of PM2.5 include vehicle exhaust, wildfires, agricultural emissions, dust, power plants, and industrial facilities. Some countries struggle more with pollution from heavy traffic or industry, while other regions have wildfires as their main concern, he said. 

“Improving air quality is very important for human health and the environment,” said Guo. To do so, he said, the global community needs to work to reduce emissions from vehicles and industry and promote the transition to clean energy. “We need to find solutions to improve air quality for every person,” he said.