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.
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 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.
- Yang et al found that patients with severe Covid-19 infections requiring, for instance intensive care, were two times as likely to have had pre-existing diseases, especially heart disease, strokes, chronic lung diseases and diabetes—all of which are known to be caused by air pollution. (International Journal of Infectious Diseases, March 5, 2020)
- Zhu et al analyzed 120 cities in China and found a significant relationship between air pollution and COVID-19 infection after controlling for confounding factors. (Science of the Total Environment, July 20, 2020)
- Tian et al found that places with higher levels of nitrogen dioxide pollution (10 micrograms per cubic metre) in the five years before the pandemic had 22% more Covid-19 cases, while higher levels of small particle pollution saw a 15% rise in infection rates. (Beijing Normal University, PREPRINT posted April 24, 2020)
- Wang et al found that particulate matter pollution was positively associated with increased cases of COVID-19. (Lanzhou University, PREPRINT posted April 14, 2020)
- Yao et al found that air pollution was positively associated with higher fatality rates from COVID-19. (Fudan University, PREPRINT posted April 10, 2020)
- Yao et al found that air pollution may be associated with the transmission of COVID-19. (Fudan University, PREPRINT posted April 10, 2020)
- Ogen found that of the coronavirus deaths across 66 administrative regions in Italy, Spain, France and Germany, 78% of them occurred in just five regions, and these were the most polluted. (Science of the Total Environment, July 15, 2020)
- Conticini et al found high death rates seen in the north of Italy correlated with the highest levels of air pollution. (Environmental Pollution, June 2020)
- Travaglio et al found air pollution levels in England are associated with COVID-19 cases and deaths. (University of Cambridge, PREPRINT posted April 28, 2020)
- Setti et al detected Coronavirus on particles of air pollution while investigating whether this could enable it to be carried over longer distances and increase the number of people infected. (University of Bologna, PREPRINT posted April 24, 2020)
- Setti et al found that higher levels of particle pollution could explain higher rates of infection in parts of northern Italy before a lockdown was imposed. (University of Bologna, PREPRINT posted April 17, 2020)
- Coccia found that the rapid spread of COVID-19 in North Italy has been strongly associated with air pollution. (National Research Council of Italy, PREPRINT posted April 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)
- Cui et al found that someone living in a highly polluted area of China was more than twice as likely to die from SARS than someone living in an area with cleaner air. (Environmental Health, November 20, 2003)
- During the SARS epidemic in 2003, Kan et al found that increases in particulate matter air pollution increased risks of dying from the disease. (Biomedical and Environmental Sciences, November 2019)
- Researchers have found that several viruses, including adenovirus and influenza virus, can be carried on air particles. Zhao et al found that particulate matter likely contributed to the spread of the 2015 avian influenza. (Scientific Reports, August 13, 2019)
- Chen et al found that air pollution can accelerate the spread of respiratory infections. (Environment International, January 2017)
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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.