One thing in common in most countries: polluted air

Only 10 out of 134 countries and territories met the standards of World Health Organization for a widespread form of air pollution, according to air quality data compiled by IQAir, a Swiss company.

The contamination studied is called fine particles, or PM2.5, because it refers to solid particles smaller than 2.5 micrometers:

small enough to enter the bloodstream.

PM2.5 is the solution more deadly of air pollution and cause millions of premature deaths every year.

“Air pollution and climate change have the same culprit, which is fossil fuels,” said Glory Dolphin Hammes, CEO of IQAir’s North American division.

The World Health Organization sets a guideline that people should breathe no more than 5 micrograms of fine particles per cubic meter of air, on average, for a year.

The US Environmental Protection Agency recently proposed tightening its standard from 12 to 9 micrograms per cubic meter.

The few oases of clean air that meet World Health Organization guidelines are mostly islands, as well as Australia and the northern European countries, Finland and Estonia.

Among the underachievers, where the vast majority of the human population lives, the countries with the worst air quality were mostly located in Asia and Africa.

Where is the dirtiest air found?

The four most polluted countries in the IQAir ranking for 2023 (Bangladesh, Pakistan, India and Tajikistan) are found in southern and central Asia.

Air quality sensors in nearly a third of the region’s cities have reported fine particle concentrations greater than 10 times higher to WHO guidelines.

This is a proportion that “far exceeds any other region,” the report’s authors wrote.

The researchers pointed to car traffic, coal and industrial emissions, particularly those from brick kilns, as the region’s main sources of pollution.

Farmers who burn their agricultural waste seasonally contribute to the problem, as do families who burn firewood and dung for heat and cooking.

China reverses recent gains

A notable change in 2023 was a 6.3% increase in air pollution China compared to 2022, after at least five years of improvement. Beijing reported a 14% increase in PM2.5 pollution last year.

The national government announced a “war on pollution” in 2014 and has done nothing but keep going ever since.

But the steepest decline in PM2.5 pollution in China occurred in 2020, when coronavirus pandemic forced to slow down or close much of the country’s economic activity.

Dolphin Hammes attributed last year’s recovery to the reopening of the economy.

And the challenges remain:

Last year, 11 Chinese cities reported air pollution levels that exceeded WHO guidelines by 10 times or more

. The worst was Hotan, Xinjiang.

Significant gaps in the data

IQAir researchers analyze data from more than 30,000 air quality monitoring stations and sensors in 134 countries, territories and contested regions.

Some of these monitoring stations are operated by government agencies, while others are overseen by nonprofit organizations, schools, private companies, and citizen scientists.

to exist large lagoons in monitoring ground-level air quality in Africa and the Middle East, including in regions where satellite data shows some of these problems higher levels of air pollution on Earth.

As IQAir works to add data from more cities and towns in the coming years, “the worst may yet be yet to come in terms of what we are measuring,” Dolphin Hammes said.

Smoke from wildfires: a growing problem

Although North America is one of the cleanest regions in the world, fires burned 4% of forests in 2023 Canadaa surface area of ​​approximately half the size of Germanyand significantly affected air quality.

Typically, the list of the most polluted cities in North America is dominated by the United States.

But last year, the top 13 spots went to Canadian cities, many of them in Alberta.

In the United States, cities in the Upper Midwest and Mid-Atlantic states also experienced significant amounts of PM2.5 pollution from smoke from wildfires that crossed the border.

Risks of short-term exposure

It’s not just chronic exposure to air pollution that harms people’s health.

For vulnerable people, such as the young and old, or those with underlying health conditions, breathing in large quantities of fine particles over a few hours or days can sometimes be fatal.

According to a recent global study published in The Lancet Planetary Health, approximately 1 million premature deaths per year can be attributed to short-term exposure to PM2.5.

The problem is worse in East and South Asia, as well as West Africa.

Without accounting for short-term exposures, “we may underestimate the mortality burden from air pollution,” said Yuming Guo, a professor at Monash University in Melbourne, Australia and one of the study’s authors.

In the United States, disparities are widening

Within each country, air pollution and its health effects are not equally distributed.

Air quality in the United States has generally improved since the Clean Air Act of the 1970s.

Over the past decade, premature deaths due to PM2.5 exposure have declined to about 49,400 in 2019, compared to about 69,000 in 2010.

But progress has happened more quickly in some communities than others.

Racial and ethnic disparities in air pollution deaths have increased in recent years, according to a national study released this month.

US census tracts with fewer white residents have rates of PM2.5-related deaths about 32% higher than those with more white residents.

This disparity in deaths per capita increased by 16% between 2010 and 2019.

The study looked at race and ethnicity separately and found that the disparity between census tracts with the most and fewest Hispanic residents grew further, by 40%.

In the IQAir ranking, the United States performs much better than most other countries.

But deeper studies show that air quality remains a problem, said Gaige Kerr, a researcher at George Washington University and lead author of the paper on disparities published in the journal Environmental Health Perspectives.

“There is still a lot of work to do,” he said.

Kerr’s research showed that death rates were highest on the Gulf Coast and Ohio River Valley, in areas dominated by the petrochemical and manufacturing industries.

He also noted that researchers have noticed a slight increase in PM2.5-related death rates since 2016, particularly in Western states, likely due to increased wildfires.

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