As the novel coronavirus tears around the world, it’s exploiting our biggest weaknesses, from creaking health care systems to extreme social inequality. Its relationship with one pervasive and neglected problem, however, is more tangled: Air pollution has intensified the pandemic, but the epidemic has—temporarily—cleaned the skies
When new evidence emerged this week that dirty air makes Covid-19 more lethal, it surprised no one who has followed the science of air pollution—but the scale of the effect was striking. The study, which must still undergo peer review for publication, found that the tiny pollutant particles known as PM2.5, breathed over many years, sharply raise the chances of dying from the virus.
Researchers from Harvard University’s T.H. Chan School of Public Health analyzed data on PM2.5 levels and Covid-19 deaths from about 3,000 U.S. counties covering 98 per cent of the U.S. population. Counties that averaged just one microgram per cubic meter more PM2.5 in the air had a Covid-19 death rate that was 15 per cent higher.
“If you’re getting COVID, and you have been breathing polluted air, it’s really putting gasoline on a fire,” said Francesca Dominici, a Harvard biostatistics professor and the study’s senior author.
That’s because the fine particles penetrate deep into the body, promoting hypertension, heart disease, breathing trouble, and diabetes, all of which increase complications in coronavirus patients. The particles also weaken the immune system and fuel inflammation in the lungs and respiratory tract, adding to the risk both of getting Covid-19 and of having severe symptoms.
Dominici and her colleagues illustrated the impact with a specific example: Manhattan, the current epicentre of the pandemic, where PM2.5 averages range as high as 11 micrograms per cubic meter, and where 1,904 deaths from Covid-19 had been reported as of 4th April. Had particle levels averaged just one unit lower over the past two decades, the researchers calculated, 248 fewer people would have died over the past several weeks. And of course, the toll has mounted since 4th April.
But while pollution inhaled in the past is still causing harm today, the temporary experience of cleaner air brought about by widespread shutdowns may offer lessons for the kind of world we want to build after the pandemic.
People so accustomed to the pollution they hardly think about it may realise, “Actually, I really do quite enjoy clean air: Do you think we could get it, or keep it?” says Simon Birkett, founder and director of Clean Air in London, an advocacy organisation. “There’s a chance to really get people to stop, take a deep breath,” and reflect on questions like “How was your asthma during this period?”
Although a near-halt in normal life and economic activity is no one’s idea of a good way to reduce pollution, the brief respite might, in Birkett’s view, turn this dark time into “a catalyst, or a tipping point, which could get us to say ‘Clean air—there’s something special about it.’”
CLEANER PANDEMIC SKIES
From China’s Hubei province to industrial northern Italy and beyond, pollution levels have plummeted as lockdowns aimed at slowing the viral spread have shuttered businesses and trapped billions of people at home. In India, where air pollution is among the world’s worst, “people are reporting seeing the Himalayas for the first time from where they live,” Lauri Myllyvirta, lead analyst at the Helsinki-based Centre for Research on Energy and Clean Air, said in an email.
India’s hastily imposed shutdowns have been devastating, leaving hundreds of thousands of migrant workers without homes or jobs. But in Delhi, where the air is normally choking, levels of both PM2.5 and the harmful gas nitrogen dioxide fell more than 70 per cent.