Most countries have one thing in common: unsafe air

Only 10 of 134 countries and territories met World Health Organization standards for widespread air pollution last year, according to World Health Organization figures. air quality data collected by IQAira Swiss company.

The pollution examined is called particulate matter or PM2.5, because it concerns solid particles that are smaller than 2.5 micrometers: small enough to enter the bloodstream. PM2.5 is the deadliest form of air pollution and leads to millions of premature deaths every year.

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

The World Health Organization has set a guideline that, on average, people should not inhale more than 5 micrograms of particulate matter per cubic meter of air per year. The US Environmental Protection Agency recently proposed tightening the standard from 12 to 9 micrograms per cubic meter.

The few oases of clean air that meet World Health Organization guidelines are mainly islands, as well as Australia and the northern European countries of Finland and Estonia. Among non-performers, where the vast majority of the human population lives, the countries with the worst air quality were mainly in Asia and Africa.

Where some of the dirtiest air is found

The four most polluted countries in IQAir’s 2023 rankings – Bangladesh, Pakistan, India and Tajikistan – are in South and Central Asia.

Air quality sensors in almost a third of the region’s cities reported particulate matter concentrations more than ten times higher than the WHO guideline. This was a percentage “far greater than any other region,” the report authors wrote.

The researchers pointed to car traffic, coal and industrial emissions, especially from brick kilns, as major sources of the region’s pollution. Farmers who seasonally burn their crop waste contribute to the problem, as do households who burn wood and dung for heating and cooking.

China has reversed recent gains

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

The national government announced a “war on pollution” in 2014 and has made progress since then. But the sharpest decline in PM2.5 pollution in China happened in 2020, when the coronavirus pandemic forced much of the country’s economic activity to slow or halt. Ms Dolphin Hammes attributed last year’s rebound to a reopening of the economy.

And challenges remain: Eleven cities in China last year reported air pollution levels that exceeded WHO guidelines by ten 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 disputed regions. Some of these monitoring stations are operated by government agencies, while others are overseen by nonprofits, schools, private companies and citizen scientists.

There are major gaps in ground-level air quality monitoring in Africa and the Middle East, including in regions where satellite data shows some of the highest levels of air pollution on earth.

While IQAir works to add data from more cities and countries in the coming years, “the worst is yet to come in terms of what we measure,” Ms Dolphin Hammes said.

Smoke from wildfires: a growing problem

Although North America is one of the cleaner regions in the world, wildfires burned 4 percent of Canada’s forests in 2023, an area about half the size of Germany, and significantly affected air quality.

Normally, the North American list of most polluted cities is dominated by the United States. But last year, the top 13 places all 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 wildfire smoke drifting across 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 very young and old, or those with underlying illnesses, inhaling large amounts of fine particles for just a few hours or days can sometimes be fatal. Approximately 1 million premature deaths per year can be attributed to short-term exposure to PM2.5. according to a recent global study published in The Lancet Planetary Health.

The problem is worst in East and South Asia, but also in West Africa.

Without taking short-term exposure into account, “we may be underestimating the mortality burden from air pollution,” said Yuming Guo, a professor at Monash University in Melbourne, Australia, and one of the study’s authors.

The differences in the US are increasing

Within individual countries, air pollution and its health effects are not evenly distributed.

Air quality in the United States has generally improved since the Clean Air Act of the 1970s. Over the past decade, the number of premature deaths from PM2.5 exposure has fallen to about 49,400 in 2019, from about 69,000 in 2010.

But in some communities progress has been faster than in others. Racial and ethnic disparities in air pollution deaths have increased in recent years a national study published this month.

The United States census tracts with the fewest white residents show about 32 percent more PM2.5-related deaths, compared to those with the most white residents. This disparity in deaths per capita increased by 16 percent between 2010 and 2019.

The study examined race and ethnicity separately and found that the disparity between the census tracts with the most and least Hispanic residents widened even further: by 40 percent.

In the IQAir rankings, the United States fares much better than most other countries. But studies that dig deeper show that air quality is still a problem, says Gaige Kerr, a research scientist at George Washington University and lead author of the disparities paper published in the journal Environmental Health Perspectives. “There is still a lot of work to be done,” he said.

From the research of Dr. Kerr found that death rates were highest on the Gulf Coast and in the Ohio River Valley, in areas dominated by the petrochemical and manufacturing industries. He also noted that researchers have seen a slight increase in PM2.5-related deaths starting around 2016, especially in western states, likely due to increasing wildfires.