Climate change is driving increases in unhealthy air, putting 150 million Americans – nearly half of the country’s population – at risk for associated respiratory issues amid the Covid-19 pandemic.

A recent study from Harvard University found air pollution is linked to higher death rates associated with the respiratory disease Covid-19 caused by the SARS-CoV-2 virus. Living and breathing polluted air, particularly during times of increased vulnerability, may be putting the health and lives of Americans at risk.

"Air pollution is linked to greater risk of lung infection," said American Lung Association President and CEO Harold Wimmer in a statement. "Protecting everyone from Covid-19 and other lung infections is an urgent reminder of the importance of clean air."

In its 161-page State of the Air report, the American Lung Association analyzed ozone pollution and particle pollution data from 2016, 2017, and 2018 – all of which are among the five hottest years on record. Western counties were found to be experiencing record-breaking spikes in particle pollution, largely associated with climate-spurred wildfire seasons that have swept through the western US.

Particle pollution, also known as PM2.5, is made up of unhealthy particles from wildfires, wood-burning stoves, and coal-fired plants, among other sources. These microscopic particles can become lodged in the lungs to potentially enter the bloodstream, triggering asthma attacks and other respiratory impacts. During the timeframe analyzed, most cities saw an increase in number of days where the daily particular pollution detected was higher than average, while nine states reached the most number of days with above average PM2.5 ever reported, which were largely linked to California’s deadly 2018 wildfire season. 

Worst US Cities By Daily Particle Pollution Average

1. Fresno-Madera-Hanford, California

2. Bakersfield, California

3. San Jose-San Francisco-Oakland, California

4. Fairbanks, Alaska

5. Yakima, Washington

6. Los Angeles-Long Beach, California

7. Missoula, Montana

8. Redding-Red Bluff, California

9. Salt Lake City-Provo-Orem, Utah

10. Phoenix-Mesa, Arizona

 Worst US Cities For Annual Particle Pollution

1. Bakersfield, California

2. Fresno-Madera-Hanford, California

3. Visalia, California

4. Los Angeles-Long Beach, California

5. San Jose-San Francisco-Oakland, California

6. Fairbanks, Alaska

7. Phoenix-Mesa, Arizona

8. El Centro, California

9. Pittsburgh-New Castle-Weirton, PA-OH-WV

10. Detroit-Warren-Ann Arbor, Michigan

Ozone pollution, also known as smog, is a respiratory irritant that can cause shortness of breath and respiratory issues as well as shorten lifespan. Warmer temperatures associated with climate change can drive the formation of ozone pollution and make it more difficult to clean up. Across the nation, more than 137 million people live in an area with what is considered a “failing grade” for ozone pollution.

Top 10 Most Ozone-Polluted Cities

1. Los Angeles-Long Beach, California

2. Visalia, California

3. Bakersfield, California

4. Fresno-Madera-Hanford, California

5. Sacramento-Roseville, California

6. San Diego-Chula Vista-Carlsbad, California

7. Phoenix-Mesa, Arizona

8. San Jose-San Francisco-Oakland, California

9. Las Vegas-Henderson, Nevada

10. Denver-Aurora, Colorado

Air quality has improved in some communities, among them the San Francisco Bay Area, which experienced less ozone air pollution than previously recorded. The nation’s four cleanest cities were those that did not experience high ozone or particle pollution days and also saw the lowest annual particle pollution levels.

Cleanest US Cities (not ranked)

• Bangor, Maine
• Burlington-South Burlington-Barre, Vermont
• Honolulu, Hawaii
• Wilmington, North Carolina

Even so, the report notes that many Americans are still breathing unhealthy air that affects everyone, particularly vulnerable populations like children, the elderly, and people living with underlying health conditions such as asthma and lung disease.

"The science is clear: the nation needs stronger limits on ozone and particle pollution to safeguard health, especially for children and people with lung disease. Every family has the right to breathe healthy air – and the right to know when air pollution levels are unhealthy,” concluded Wimmer.