trekandshoot/Alamy
Living in a part of the United States with dirty air has been linked to a significantly greater risk of dying from covid-19, raising the prospect of air pollution data being used to forecast which areas may need the most help treating people with the illness.
As long-term exposure to air pollution weakens the lungs, and covid-19 attacks them, researchers worldwide have been racing to establish whether poor air quality makes the disease more severe. Links have been drawn, but many studies fail to account for other possible reasons for the associations, such as population density.
Francesca Dominici at Harvard University and her colleagues have now found that each extra microgram of tiny particulate matter – PM2.5 – per cubic metre of air over the long term increases the covid-19 mortality rate by 11 per cent. That puts the link between covid-19 and air pollution roughly on a par with the link between the disease and smoking.
Advertisement
“This is the first study that provides some consistent evidence that, if you’re living in a [US] county with a higher level of fine particulate matter, it increases the risk of covid mortality,” says Dominici. Her team examined covid-19 death data up to 18 June for 3089 US counties, and modelled PM2.5 levels for 2000 to 2016 down to county level.
Importantly, the link between air pollution and higher death rates was clear even after adjusting results for 20 other possible explanations, including smoking, wealth, age and race. However, Dominici says a big limitation of the analysis is that the data on deaths, pollution and the other potential reasons is at an area level, rather than the level of individuals, hindering its accuracy. Still, she says it remains the best way to measure links until individual-level data, which is being captured, becomes available to researchers in a year or so.
While there is no way to undo the harm that long-term air pollution inflicts, Dominici says finding the link with covid-19 deaths “matters a tonne”. For example, areas that have suffered from dirty air could be prioritised for more hospital beds or PPE. And with covid-19 likely to be with us for years, efforts to make air cleaner now could help people cope with the illness in future.
Jonathan Grigg at Queen Mary University of London, who wasn’t involved in the study, says it is good research and in line with other emerging evidence. “It’s entirely possible that relatively small changes [in pollution exposure] are going to be associated with increased risk [in covid-19 mortality rates]. It’s plausible,” he says.
Mark Miller at the British Heart Foundation and University of Edinburgh, UK, who also wasn’t involved in the research, says we now need to better understand the biology underlying the link between dirty air and covid-19 mortality rates. “Could these findings simply be because both air pollution and covid-19 affect the same vulnerable groups – the elderly and those with respiratory or cardiovascular disease – or is there something more going on?”
Journal reference: Science Advances, DOI: 10.1126/sciadv.abd4049
More on these topics: