LONDON (BLOOMBERG) - Even before the pandemic struck, outdoor air pollution was linked to the deaths of as many as nine million people each year. Now two new studies show that Covid-19 patients are more likely to die if they live in regions with high levels of air pollution.
Air pollution affects human health in insidious ways. The burning of fossil fuels in cars and factories creates soot and other too-small-to-see particles. Every breath filled with these particles slowly increases the risk of heart problems, strokes, asthma, pneumonia and lung cancer.
These particles are so small that they end up in almost every organ in the body. The longer we study air pollution's effects, the longer the list of diseases it is linked to - now including Covid-19.
"The latest science is showing that there seem to be no 'safe' levels of air pollution," said Dr Gretchen Goldman, research director at the Centre for Science and Democracy at the Union of Concerned Scientists.
The new studies - one from Harvard University looking at the United States and the other from the University of Siena looking at Italy - show just how bad it can get when air pollution collides with a rapidly spreading respiratory disease.
The Harvard researchers found that a long-term air pollution increase of 1 microgram per cubic m of small particles can raise the risk of dying from Covid-19 by 15 per cent. The study is yet to undergo peer review but multiple experts familiar with the findings told Bloomberg that the results aren't surprising.
Covid-19 doesn't impact everyone equally. In those who suffer severely, the virus is thought to move from the upper respiratory tract, where it can cause a sore throat, to the lower respiratory tract, where it causes inflammation in the lungs, which can lead to death if it spirals out of control.
The authors of the University of Siena study wrote that, because air pollution "impairs the first line of defence" of the upper respiratory tract, it likely explains why those who live in areas with higher air pollution might fall prey to the disease more than others.
Past evidence makes the case stronger. A study published in 2003 found that higher air pollution caused greater deaths from Sars, which was caused by a cousin of the current strain of coronavirus.
A range of studies have found that air pollutants are linked to increased risk from influenza-type illnesses. Air pollution levels are higher in poorer parts of a city or state.
"It adds yet another layer of injustice to who is going to be affected by this virus," Dr Goldman said. The short-term respite from air pollution that most big cities in the world are experiencing because of lockdown measures will save some lives, but only long-term reductions in air pollution can have lasting impacts.
The good news is that policymakers know what needs to be done: improving access to public transport, electrifying the transport fleet, raising regulations or pricing emissions on power plants and factories, and developing new technology alternatives to polluting industries, such as steel and cement. All of these measures lead to cleaner air (and lower carbon emissions).
Better still, the interventions lead to higher productivity.
"Air pollution is a drag on economic growth and solutions to address it are enormously cost effective," said Dr Aaron Bernstein, director of Harvard C-Change, a centre dedicated to climate change and public health. A 2011 study from the US Environmental Protection Agency found that every US$1 (S$1.40) spent on lowering air pollution returns as much as US$30.
Some people with influence might be making the connection between air pollution and ill-health more clearly than before.
"We paid people's lives for the lesson, and we should never do it again," said Ms Cai Xue'en, delegate of the National People's Congress and adviser to China's supreme court, in the context of the country's Covid-19 death toll. "I think environmental protection will rank even higher for both the central and local governments."
