Coronavirus and climate change | Coronavirus and heatwaves

We know that air pollution can cause health problems, like heart attacks, strokes, diabetes and high blood pressure, that have been identified as the pre-existing medical conditions that raise the chances of death from COVID-19 infection. Emerging research, including a study from Harvard T.H. Chan School of Public Health, has now suggested that breathing more polluted air over many years may itself worsen the effects of COVID-19.

What Preliminary Research on Air Pollution and Coronavirus Means

A recent Harvard Chan study led by Xiao Wu and Rachel Nethery and senior author Francesca Dominici found an association between air pollution over many years with an 8% increase in mortality from COVID-19 infection for every 1 microgram/cubic meter increase in air pollution (for comparison, many Americans breathe air with 8 micrograms/cubic meter of particulate matter).

For those who might be uncomfortable with these findings because they don’t appear in a peer-reviewed publication (the paper is under review for publication), bear in mind:

Peer review takes time. Peer review and publication in a journal can take weeks or months. That’s a long time in the midst of an epidemic that we know can spread rapidly in a week.

Their results clearly matter to health right now. In other instances of health research, such as drug trials, studies are stopped the moment when people who get an experimental drug are significantly more or less likely to do better than those who don’t. Continuing to keep someone in the dark when a study shows that a person may be more likely to survive had they been taking the experimental drug is immoral. While we can’t stop the air pollution experiment like we can a drug trial, we can at least take a pause to consider policies that will make air pollution worse, especially when so many other studies have found that air pollution can increase risk of death from respiratory infections.

The EPA is rolling back pollution standards right now. The Harvard results come in the midst of a host of policy rollbacks by the Environmental Protection Agency that stand to make air pollution, and its harms, worse, particularly for vulnerable communities. These include reducing the Mercury and Air Toxic Standards, replacing the Clean Power Plan with the ACE rule, choosing not to strengthen soot pollution regulations despite scientists’ recommendations, lowering fuel efficiency standards, and relaxing enforcement of environmental regulations.

“There is a respiratory virus that kills people out there – this is not the right time to give permits to industry to pollute our air,” Dominici told The Guardian.

Dr. Aaron Bernstein, Interim Director at the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health (Harvard Chan C-CHANGE), who was not involved in the Harvard study, says that higher death rates that have been observed among the poor and people of color in the United States reflect existing health and economic inequalities that both contribute to, and result from, greater exposure to air pollution.

“In places where air pollution is a chronic problem, we have to pay particular attention to individuals who may be more exposed or vulnerable than others to polluted air, such as the homeless and those with chronic medical problems,” says Dr. Bernstein. “These individuals may need more support than they did even before coronavirus came along.”

Research on Air Pollution and Coronavirus

As Don Kennedy, the former head of the FDA and Editor-in-Chief of Science magazine (one of the world’s premier peer-reviewed scientific journals) once said, “Replication is the ultimate test of truth in science.”

The Harvard study is one of several that have now suggested that air pollution is affecting COVID-19 mortality. Researchers analyzing 120 cities in China found a significant relationship between air pollution and COVID-19 infection, and of the coronavirus deaths across 66 regions in Italy, Spain, France and Germany, 78% of them occurred in five of the most polluted regions. There’s also evidence from previous outbreaks like SARS, which was also a coronavirus, as well as many other respiratory infections including influenza, that breathing more polluted air increased risks of death.



United States

      • Petroni et al found an increase in exposure to hazardous air pollutants (HAPs) is associated with a 9% increase in COVID-19 mortality. (Environmental Research Letters, September 11, 2020)
      • Wu et al found an association between air pollution over many years with an 8% increase in mortality from COVID-19 infection for every 1 microgram/cubic meter increase in air pollution. (Harvard T.H. Chan School of Public Health, PREPRINT posted April 24, 2020)
      • Liang et al found that people living in communities with more long-term exposure to tailpipe emissions were associated with higher rates of dying from COVID-19, with a 4.6ppb increase in NO2 exposure (which primarily comes from urban traffic) resulting in a 7% increase in the case fatality rate after controlling for other factors that may increase risk of dying from the disease. (Emory University, PREPRINT posted May 7, 2020)

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Dr. Aaron Bernstein

Aaron Bernstein MD, MPH

Aaron examines the human health effects of global environmental changes with the aim of promoting a deeper understanding of these subjects among students, educators, policy makers, and the public.

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