Surrounded by hazy conditions, a window washer cleans a window at the View of DC observation deck on June 8 in Arlington, Virginia. Smoke from wildfires in Canada have darkened the skies and affected the air quality in parts of the United States. Image Credit: The Washington Post

Worsening air pollution and increased resistance to antibiotics are two of the world’s most urgent public health concerns, contributing to millions of premature deaths per year - and a new study suggests they might be related.

Researchers from Zhejiang University and the University of Cambridge have found “significant correlations” worldwide between air pollutants known as PM 2.5 - tiny particles of solids or liquids in the air such as dust, dirt and soot - and antibiotic resistance, according to a paper published this month in the Lancet Planetary Health journal.

The link shown in data from 116 countries over 18 years is “increasing at an accelerating rate,” the researchers said, “which could hasten the beginning of a so-called post-antibiotic era” in which superbugs, or drug-resistant diseases such as methicillin-resistant Staphylococcus aureus (MRSA), could become prevalent.

For years, scientists have been sounding the alarm about the deadly consequences of antibiotic resistance, which is sometimes called the “silent pandemic” and has long been attributed to the overuse and misuse of antibiotics. But the new peer-reviewed study’s findings suggest pollution could also be an important contributing factor. The authors estimate that antibiotic resistance derived from air pollution caused some 480,000 premature deaths in 2018, and if nothing is done to remedy the situation in the future, that death toll could rise by 56.4 per cent by 2050.

Worrying trends

The findings point to an intersection of two worrying trends. From 2016 to 2019, deaths caused by antibiotic resistance increased more than 80 per cent, researchers write in the paper.

Meanwhile, air pollution is likely to worsen worldwide as a result of climate change. A study published in March found that nearly every person on the planet is exposed to levels of air pollution that the World Health Organization considers unhealthy.

This summer, bad air quality from wildfires left portions of the United States and Canada in an ominous haze, sparking renewed concern about the health consequences of pollution, which has already been linked to cancer, respiratory illnesses, cardiovascular disease and even dementia and depression, among other conditions. And in many parts of the world, air that burns your throat and stings your eyes is a regular struggle.

“Pollution has a massive effect on human health even without considering antibiotic resistance,” Mark A. Holmes, a professor of microbial genomics and veterinary science at Cambridge University who worked on the paper, wrote in an email. “This correlation between antibiotic resistance and this type of pollution provides another incentive to tackle pollution,” he said.

The study was observational, so the authors emphasize that additional research would be needed to determine any sort of causal relationship between air pollution and resistance to antibiotics. Still, the work is significant in that it is the “first report on the relationship between PM2.5 and clinical antibiotic resistance worldwide,” the authors write.


Holmes said the results were “surprising” in that they suggest “there is value in looking beyond the simple reduction in antibiotic use when tackling antibiotic resistance.”

Previous research has suggested that rising local temperatures and population density are also associated with increasing antibiotic resistance in common pathogens.

Antibiotic resistance was responsible for at least 1.27 million deaths globally in 2019, according to the Centers for Disease Control and Prevention, and in December the World Health Organization warned about high levels of resistance in bacteria causing life-threatening bloodstream infections in hospitals and making it harder to treat common infections.

Contrary to prevailing beliefs, it is not the patient who becomes resistant to antibiotics but the pathogen itself. Each time we successfully use an antibiotic, it kills off the vulnerable pathogens and leaves behind ones with drug-resistant elements, which then multiply, making it more difficult to use the medication effectively in the future. Holmes calls it “simple Darwinian natural selection.”

While more research is needed to determine the underlying mechanism behind air pollution’s apparent link to antibiotic resistance, Hong Chen, a professor of environmental engineering at Zhejiang University who worked on the study, wrote in an email that air has been recognized as a “key vector for disseminating antibiotic resistance.” PM 2.5 has been shown to carry a variety of antibiotic-resistant bacteria and antibiotic-resistant genes, “which are transferred between environments and directly inhaled by humans,” she said.

In the paper, the authors call on governments and the public to do what they can to intervene, writing that “the harm caused by global air pollution has no borders.”