Air Pollution Exacerbates COVID-19 Mortality, Study Finds

Air pollution and COVID-19

Key Takeaways

  • A new study links higher COVID-19 mortality rates to areas with higher levels of hazardous air pollutants (HAPs).
  • Several other studies have found similar links between the two.
  • While you can't control the hazardous air pollutants in your overall area, there are some steps you can take to improve indoor air quality in your home.

Air pollution is contributing to and is linked to COVID-19 mortality in the U.S., a new study finds.

According to a September report in IOP Science, the rise in the respiratory hazard index is linked to a 9% increase in death among patients with COVID-19. That is, the higher the index is, the more it correlates to poor outcomes in patients with COVID-19.

The U.S. Environmental Protection Agency’s (EPA) hazard index (HI) ranks air toxins based on any adverse health effects they may cause, and to what extent. Hazardous air pollutants (HAPs) are those that are known or suspected to cause cancer or other serious health and environmental issues. They include volatile organic compounds and metals. According to the EPA, HAPs are linked to a higher risk of respiratory and immune conditions.

The research team looked at HAPs that lead to the most respiratory toxicity weighted exposure in the U.S., such as formaldehyde, acetaldehyde, acrolein, naphthalene, and diesel particulate matter, Michael Petroni, one of the study authors and PhD student at the SUNY College of Environmental Science and Forestry in New York, tells Verywell.

The study didn’t look at acute exposure from specific chemicals, but hypothesized that higher levels of chronic exposure, along with other contributing factors, increase mortality risk from COVID-19, Petroni says.

The researchers believe HAPS contribute to COVID-19 vulnerability because they are tied to chronic respiratory stress. “Pollution does directly affect the lungs,” he says.

Air pollution may affect COVID-19 mortality rates by impairing lung function, or by creating or exacerbating chronic lung conditions such as COPD and asthma. Petroni says it may contribute to other pre-existing vulnerabilities like heart disease.

What This Means For You

Higher hazardous air pollutants (HAPs) may be contributing to more severe COVID-19 cases in certain areas. There are steps you can take in your own home to improve indoor air quality, like properly maintaining your ventilation system and preventing mold.

Are Wildfires Impacting COVID-19 Patients?

The wildfires in the Western U.S. are contributing to the levels of HAPs in the air. Wildfires produce HAPs, specifically particulate matter, formaldehyde, and acetaldehyde, Petroni says.

“These are some of the main respiratory system irritants that we focused on linked to higher COVID-19 death rates,” he says.

Changes to forest and wildfire management can help reduce massive burns, and therefore, lower HAP levels, Petroni says.  

“While wildfires are extremely visible sources of HAPs, they are not the largest contributor to exposure across the country or even out West,” he says. “HAP exposure is insidious and often unseen, and it arises from combustion of any kind.”

In other words, HAPs can be produced in our homes, he adds. HAPs aren’t just found in big cities, either. Some areas of the U.S. with higher than normal levels are in the Southeastern United States.

How to Protect Yourself From Wildfire Smoke Indoors

The EPA recommends taking some steps to protect yourself from wildfire smoke indoors:

  • Keep windows and doors closed.
  • Use fans and air conditioning to stay cool. 
  • Reduce the smoke that enters your home by adjusting your heating, ventilation, and air conditioning (HVAC) system or air conditioner to keep smoke out.
  • Use a portable air cleaner or high-efficiency filter to remove fine particles from the air.
  • Avoid activities that create more fine particles indoors, like smoking cigarettes or using gas stoves.
  • Air out your home by opening windows or the fresh air intake on your HVAC system when the air quality improves, even temporarily.

Evaluating Air Pollution and COVID-19

Previous research has looked at links between COVID-19 mortality and population-based exposure to nitrogen dioxide, ozone, and particulate matter. Though lockdowns lowered air pollution levels according to some research, other studies have linked higher levels of pollutants to increased levels of COVID-19 infection, hospitalization, and death.

A study out of Harvard University, not yet peer-reviewed, is looking at long-term effects of participate matter on COVID-19 deaths. It reports that people who live in a county with high levels of fine particulate pollution are 8% more likely to die from COVID-19 compared to someone in a region that has one microgram per cubic meter less.

"The nation has known for some time that long-term exposure to particle pollution can worsen symptoms of lung disease, increase susceptibility to lung infection, trigger heart attack and stroke, and can even cause lung cancer and premature death," Harold Wimmer, president and CEO of the American Lung Association (ALA), said in an April statement. "This new research from Harvard now links particle pollution exposure to a dramatically higher death rate from COVID-19."

He cited the EPA's efforts to update the air standards and said the ALA wants a significant strengthening of the annual standard. The EPA proposed keeping the standard as-is.

“These findings illustrate that far too many Americans are facing multiple threats to their lung health at once, and when taken together, these different threats to lung health impacts can amplify each other," Wimmer said. "Even as the Lung Association and the nation respond to the urgent health needs of the COVID-19 crisis, we cannot afford to delay cleanup of dangerous air pollution. In fact, it is more important than ever.

Researchers from the Netherlands also looked at air quality readings gauging levels of nitrogen dioxide, sulfur dioxide, and fine particulate matter. Areas with higher pollutant levels typically had more COVID-19 cases, hospitalizations, and deaths.

Petroni hopes their latest study will trigger more research into what constitutes “safe” levels of chronic air pollutant exposure.

“Our main goal was to test the emerging hypothesis that air pollution risks and COVID-19 mortality risks are related,” he says. The findings are based on county averages and do not yet have the specificity needed to make any individual level conclusions.

How You Can Improve Your Indoor Air Quality

The EPA shares a number of ways you can help protect the indoor air quality in your own home. Some actions you can take include:

  • Test for radon or determine how to fix high levels of radon.
  • Reduce asthma triggers, like secondhand smoke and dust mites.
  • Prevent mold by controlling moisture.
  • Keep your home and car smoke-free.
  • Install carbon monoxide (CO) alarms, and change the batteries in existing CO and smoke detectors.
  • Use and properly maintain your ventilation system.

 The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Petroni M. et al. Hazardous air pollutant exposure as a contributing factor to COVID-19 mortality in the United States. IOP Science. Sept. 2020. doi:10.1088/1748-9326/abaf86

  2. U.S. Environmental Protection Agency. Hazardous air pollutants.

  3. Strum M, Scheffe R. National review of ambient air toxics observations. J Air Waste Manag Assoc. 2016;66(2):120-33. doi:10.1080/10962247.2015.1076538

  4. United States Environmental Protection Agency. Wildfires and indoor air quality (IAQ).

  5. Venter Z, et al. COVID-19 lockdowns cause global air pollution declines. PNAS. Aug. 2020. doi:10.1073/pnas.2006853117 

  6. Wu X, et al. Air pollution and COVID-19 mortality in the United States: strengths and limitations of an ecological regression analysis. Sci. Adv. (in press) 2020 

  7. American Lung Association. Study shows importance of continued enforcement of air pollution control measures.

  8. U.S. Environmental Protection Agency. National ambient air quality standards (NAAQS) for PM.

  9. Cole MA, et al. Air pollution exposure and Covid-19 in Dutch municipalities. Environ Resour Econ (Dordr). Aug. 2020. doi:10.1007/s10640-020-00491-4

  10. U.S. Environmental Protection Agency. Protect indoor air quality in your home.

By Kristen Fischer
Kristen Fischer is a journalist who has covered health news for more than a decade. Her work has appeared in outlets like Healthline, Prevention, and HealthDay.