Nearly half of Americans are breathing dirty air, and the Western region of the U.S. is vulnerable to a potentially deadly combination of wildfire-generated air pollution and coronavirus if the pandemic continues into fire season as expected.

“There’s an association between particulate air pollution and lower respiratory infection like COVID-19,” said Dr. John Balmes, a volunteer spokesman for American Lung Association and professor of medicine at the University of California, San Francisco.

“If the pandemic is still a problem in California and we have a big wildfire, that could increase the risk of people getting infected with the SARS-CoV-2 virus and increase the risk of progressing to severe COVID-19.”

That’s because wildfire smoke contains a lot of fine particulate, and inhaling toxic soot irritates the lungs and increases the risk of lower respiratory tract infections such as bronchitis and pneumonia, he said. It’s a scenario that could put the general public at greater risk for COVID-19.

The danger is that immune cells that protect the lungs from viruses and bacteria, called alveolar macrophages, become overwhelmed, Balmes said. “If they’re unable to work properly because they’re overloaded with wildfire smoke particulate, then there’s increased risk of infection” with the virus that causes COVID-19.

During the Camp Fire that destroyed the town of Paradise, Calif., in November of 2018, particulate levels were higher than ever measured in San Francisco, he said. 

“It would be a perfect storm of bad air pollution and bad virus if we still have a lot of COVID-19 around when we have another big wildfire.”

Outdoor air pollution comes from a combination of gases and particles driven by a range of contributors, including motor vehicle emissions, wildfires, refineries, power plants, secondhand cigarette smoke and woodsmoke from heating homes. There are several different kinds of air pollution commonly measured: particle pollution or soot (both short-term and year-round) and ozone pollution or smog.

Exposure to air pollution causes or exacerbates a host of illnesses including asthma, chronic obstructive pulmonary disease (COPD), lung cancer, heart attack and stroke, and it can lead to premature death. It’s especially dangerous for children, older adults, those with compromised immune systems, cardiovascular and lung disease, and people of color, who disproportionately live near industrial and high-traffic areas. 

More than 21 million Americans live in counties with unhealthy levels of year-round particle pollution, according to the American Lung Association’s State of the Air 2020 report, released April 21. That’s more than in the last three State of the Air reports. Bakersfield, Calif., had the country’s worst year-round particle pollution.

Preliminary findings link long-term exposure to air pollution to poor outcomes from COVID-19, the disease resulting from the novel coronavirus. A recent study from Harvard’s T. H. Chan School of Public Health suggests that people who live in areas with higher levels of fine particulate (PM 2.5) air pollution are more likely to die of COVID-19 than those who live in areas with less dirty air.  

Dr. Robert Redfield, director of the Centers for Disease Control Control, told the Washington Post he is concerned that the coronavirus may rebound in a second wave later this year that is more difficult than the first, around the same time when seasonal flu often stretches hospital resources thin.

In some areas, like parts of California, another element, wildfire-driven air pollution, may add to the COVID-19 healthcare burden during the fall when fires are most likely.

Both COVID-19 and a warming climate are crises of the environment, said Dr. Mona Sarfaty, executive director of the Medical Society Consortium on Climate and Health at George Mason University’s Center for Climate Change Communication in Fairfax, Va.

“COVID-19 and climate change are both real but different health emergencies: COVID-19 in days to months and climate change in months to years.” 

But now, some good news.

>> Gains from the Clean Air Act

The U.S. has made much progress since the Clean Air Act passed 50 years ago, but the gains are fragile, according to the State of the Air report. 

“There’s still a substantial amount of public health impact from the air pollution we still have, and unless we’re careful, we’re going to be going towards worsened air quality,” Balmes said.

In a rare upside from the effects of COVID-19, the air is about 30% cleaner as people honor stay-at-home orders, he said.

Among the cleanest cities for year-round particle pollution were Honolulu; Kahului-Wailuku-Lahaina-Hawaii; Cheyenne, Wyo.; Elmira-Corning, N.Y.; and Wilmington, N.C., the report found.

Over the long term, the Clean Air Act was successful in lowering the number of avoidable deaths 230,000 per year because of lower outdoor particulate matter, and it helped avert another 7,100 annual deaths due to lower ozone, according to estimates from the U.S. Environmental Protection Agency cited in a study published December 2019 in the Annals of the American Thoracic Society. 

Less air pollution also resulted in an estimated 200,000 fewer annual heart attacks and 2.4 million fewer asthma exacerbations per year, according to the study, the Health Benefits of Air Pollution Reduction, for which Balmes was an author. 

But advocates see these gains in peril, both from global warming and from officials who seem content to let industry concerns dominate the agenda. President Trump has announced intentions to withdraw the U.S. from the Paris Agreement on climate change, which with nearly 200 other nations would cut greenhouse gas emissions, and the U.S. Justice Department has sued California for pursuing tougher emission rules than those set by the federal government. In early April, the Environmental Protection Agency passed on a chance to tighten standards for fine particulate matter pollution.

California, the nation’s most populous state, stands out for its extremes. It has worked hard to reduce its smog and push clean, renewable energy but still has some of the highest smog levels in the country, Balmes said. “All of our hard-wrought gains could be reversed by climate change.”

Several factors have combined to put pressure on the achievements, Sarfaty said. 

“For a while there, we had air that was improving in quality on a fairly predictable basis,” she said. “As it’s gotten hotter, as climate change has been happening, we’ve had more of these heat waves and therefore more ozone production. And with increased population, we have more vehicles on the road, which produces more fumes and exhaust.”

California’s population has ballooned to nearly 40 million people today from about 24 million in 1980. 

One type of air pollution, ozone, also known as smog, often comes around in the summer months as temperatures rise. Driven by heat, it was a bigger problem in this year’s study compared with previous reports because the three years covered in the report, 2016 through 2018, were the warmest on record in the United States, with 2016 the hottest year of all. 

Los Angeles remains the city with the worst ozone pollution in the nation, a distinction it has held in all but one of the report’s 21-year history. The places with the least amount of smog? Think north and cold – Anchorage, Alaska, followed by Bangor, Maine.

>> What you can do

Exercise is a key ingredient for preventive health and health maintenance. But on a bad air pollution day, whether due to smog or soot, it’s best to stay indoors and skip the workout, especially if you have an underlying health condition. Breathing faster and more deeply with exercise doesn’t do your body any favors if the air is dirty.

“Exercising during a wildfire episode when there’s really bad smoke increases your dose of particles, so that’s harmful,” Balmes said. “The cleaner we keep the air, the safer it is when we exercise.”

Keep your car windows closed while driving, especially in stop-and-go traffic, and try to take the back roads at rush hour when possible, according to tips from the American Academy of Allergy, Asthma & Immunology. 

Pay attention to “Spare the Air” days. In California, local air management agencies send suggestions to reduce driving if possible and other measures to cut ozone levels.

Learn more about the air quality in your area, and check it in your new location if you plan to move. Check out county-level data in the American Lung Association’s State of the Air report, which “provides a lot of information that people wouldn’t otherwise be able to find easily,” Sarfaty said.