COVID-19 and Air Quality

The quality of the air we breathe can influence health outcomes for people who are exposed to COVID-19. Notably, poor air quality can increase the number of people diagnosed with COVID-19, the frequency of severe disease arising resulting from these infections, and overall disease mortality. Continue reading to learn about the relationship between COVID-19 and air quality and steps you can take to measure and improve the air quality in your environment.

What is the Air Quality Index?

The “air quality index,” or AQI is a metric used by the U.S. Environmental Protection Agency (EPA) to measure air quality. The AQI is represented by a number between 0 and 500, with higher values being associated with greater levels of air pollution and health risks. An AQI below 50 means that the air quality is good, while an AQI over 300 represents hazardous conditions. Some groups of people, such as those with chronic conditions and lung disease, are particularly sensitive to air quality, and they may begin to experience unhealthy effects at an AQI over 100.

Daily AQI Color
Levels of Concern
Values of Index
Description of Air Quality



0 to 50

Air quality is satisfactory and air pollution poses little to no risk.



51 to 100

Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.


Unhealthy for Sensitive Groups

101 to 150

Members of sensitive groups may experience health effects. The general public is less likely to be affected.



151 to 200

Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.


Very Unhealthy

201 to 300

Health alert: The risk of health effects is increased for everyone.



301 and higher

Health warning of emergency conditions: everyone is more likely to be affected.

What is the Current AQI?

The EPA monitors the air quality across the country and provides daily forecasts of the AQI. The image below displays the current AQI in the continental United States.

Visit airnow.gov to get more information about the current air quality in your area.

What Contributes to Poor Air Quality?

The EPA has established an AQI for five major air pollutants to protect public health: ground-level ozone, particle pollution, or particulate matter, including PM2.5 and PM10, carbon monoxide, sulfur dioxide, and nitrogen dioxide.

  • Ground-level ozone is formed when volatile organic compounds and nitrogen oxides react in sunlight. Ground-level ozone primarily arises from vehicle emissions, industrial emissions, and chemical solvents.
  • Particulate matter consists of tiny particles suspended in the air, such as dust, soot, and smoke. PM2.5 (particles with a diameter less than 2.5 micrometers) and PM10 (particles less than 10 micrometers across) can be inhaled deep into the lungs, causing respiratory issues. Sources of particulate matter include combustion processes, vehicle emissions, and industrial emissions.
  • Carbon monoxide is a colorless, odorless gas produced by incomplete combustion of fossil fuels, such as vehicle emissions and industrial processes. High levels of carbon monoxide can be deadly because it impacts oxygen delivery throughout the body.
  • Nitrogen dioxide is a reddish-brown gas emitted from power plants, vehicles, and other combustion processes. Nitrogen dioxide can lead to respiratory problems and contribute to the formation of smog and acid rain.
  • Sulfur dioxide is released during the combustion of fossil fuels containing sulfur, primarily from coal-fired power plants and industrial processes. Sulfur dioxide contributes to the formation of acid rain and can cause respiratory issues.

What is the Relationship Between COVID-19 and Air Quality?

Researchers have studied the relationship between COVID-19 and air quality during the coronavirus pandemic. They observed significant positive associations between air pollutants (PM2.5, PM10, nitrogen oxide, sulfur dioxide, and benzene) and COVID-19 hospital admissions. Additionally, researchers observed significant positive associations between air pollutants (PM2.5, PM10, sulfur dioxide, and benzene) and COVID-19 mortality. As a result, researchers concluded that long-term exposure to air pollution is associated with developing severe COVID-19 infection, resulting in hospitalization or death.

An outbreak of wildfires in the United States in 2020 allowed researchers to study the relationship between wildfire smoke and COVID-19. This study found strong evidence of a positive association between daily increases in PM2.5 and increased risks of COVID-19 cases and deaths, with the risks accumulating for up to four weeks. Due to the wildfires, PM2.5 concentrations increased by 220.71%, while the number of COVID-19 cases increased by 56.9% and the number of deaths caused by COVID-19 increased by 148.2%. This study demonstrates how poor air quality caused by wildfires can increase the number of people infected by COVID-19 and the prevalence of severe outcomes from those infections.

How Can I Protect Myself Against Air Pollution?

Whether you are concerned about the health effects of air pollution during wildfire season or you are a long COVID patient who is experiencing symptom exacerbations because of air pollution, there are strategies you can use to protect yourself:

  • Check daily forecasts.
  • Stay indoors, avoid exercising outdoors
  • Familiarize yourself with warning signs, including the smell of smoke and eye or throat irritation.
  • Close doors, windows, and fireplace dampers.
  • Purify indoor air with a HEPA filter.
  • Use an N-95 or N-100 face mask.
  • Close the windows of your car and use the “recirculate” AC setting.
  • Contact your physician if you are having trouble breathing.

If you experience any of the following symptoms, you should talk with your health care provider for further guidance: wheezing, shortness of breath, difficulty taking a full breath, chest heaviness, lightheadedness, dizziness, and persistent cough or painful breathing. Symptoms can appear as much as 24-48 hours after exposure to severe pollution.

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