Wildfire Smoke More Dangerous for Your Lungs Than Other Pollution

Azusa fire

 Mario Tama / Getty Images

Key Takeaways

  • High concentrations of fine particle pollution from wildfire smoke drove an increase of up to 10% in hospital admissions for respiratory issues, a new study finds.
  • While other sources of pollution seem to be declining, wildfire smoke pollution is becoming more prevalent due to climate change.
  • Fine particles in wildfire smoke can seep into the lungs and bloodstream, causing various respiratory and cardiovascular health issues.

Last year, wildfires raged across the Western U.S., enveloping entire cities in smoke and exacerbating respiratory issues for many. As climate change drives more intense wildfire seasons, these pollutants being spewed into the air may be bringing dire health consequences.

New research finds that fine particles from wildfire smoke affect respiratory health more than those from other sources of pollution like car emissions. In a study published earlier this month in Nature Communications, researchers found that hospitalizations from wildfire smoke fine particle matter were up to 10 times greater than those from other pollution sources.

Particulate Matter

Also called particle pollution, particulate matter is a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen. Others are so small and fine they can only be detected using a microscope.

The study looks at the risk of tiny particles with diameters of up to 2.5 microns, or one-twentieth the size of a human hair. These airborne PM2.5 particles, as they’re called, are tiny enough to embed themselves deep into the lungs when people inhale them.

“PM2.5 has not really been decreasing and one of the reasons why is because wildfires are growing and becoming more frequent and intense,” lead study author Rosana Aguilera, PhD, a postdoctoral researcher at the University of California, San Diego Scripps Institution of Oceanography, tells Verywell.

What This Means For You

Experts recommend tending to your lung health before fire season begins this summer to decrease the risk of exacerbated respiratory issues. If you have a history of lung issues, make sure any of your lung medications or inhalers are up to date. If you don't have lung disease, experts recommend boosting your immune health with a flu shot. Overall, on days of poor air quality, consider wearing a mask with N95 quality or more.

What Smoke Does to Your Respiratory Tract

Studies show that PM2.5 causes inflammation in the lungs, regardless of what the particles are made of. Additionally, they are small enough to move through the respiratory tract and into the bloodstream, where they can impact vital organs.

Inflammation due to these tiny particles can cause respiratory symptoms like wheezing, shortness of breath, coughing, runny nose, and sore throat. One of the dangers of wildfire smoke, in particular, is that it can release high amounts of pollution persistently over several days, weeks, or even months.

“The repeated inhalation of these particles over a prolonged period of weeks to months leads to an inflammation that is not able to cure itself or resolve itself, and subsequently leads to severe enough symptoms to the point that one may need hospitalization,” Reza Ronaghi, MD, an interventional pulmonologist at the University of California, Los Angeles Medical Center who is not affiliated with the study, tells Verywell.

Ronaghi says that during the wildfire season, the most vulnerable people are those who already have lung disease. The inflammation caused by inhaling smoke particles can exacerbate symptoms, possibly leading to hospitalizations

In the study, researchers did not break down the data by people’s medical conditions or specific reasons for hospitalization.

There may be other factors that affect the toxicity of wildfire smoke. For instance, the kind of tree that burns and the temperature at which it burns may influence the composition of particles that are released into the air.

“Wildfire is mainly biomass burning," Aguilera says. "But it may also go through some infrastructure and housing and that might release additional chemicals through smoke that we inhale."

To piece apart exactly which particles found in wildfire smoke are most toxic will require more research.

Increased Hospitalizations

Aguilera and her team studied 14 years of hospital admissions data, from 1999 to 2012. To single out PM2.5 from wildfires compared with other sources of pollution, the team estimated wildfire smoke exposure in Southern California, where the Santa Ana winds stoked fires and drove smoke toward heavily populated areas.

When there was a 10 microgram-per-cubic meter increase in PM2.5 from wildfire smoke, hospital admissions increased between 1.3 to 10%. Comparatively, the same increase in PM2.5 from other sources of pollution drove up hospital admissions rates by 1%.

Aguilera says this data adds to our growing understanding of the dangers of inhaling wildfire smoke. Previous research indicated that wildfire smoke can be highly toxic and harmful to lung health, but the large-scale public health effects had not been adequately studied. 

“In light of what we have seen in terms of toxicological studies and other research, perhaps it's not surprising that wildfire smoke may be more harmful, but it was still important to confirm this at the population level,” Aguilera says.

How to Protect Yourself From Wildfire Smoke

Experts say that with rising temperatures, wildfire seasons are likely to grow longer and more intense. If you live in a place that commonly experiences wildfires, it may be important to tend to your lung health before wildfire season hits in the summer months. 

If You Have a History of Lung Disease

People with a history of lung disease are more vulnerable to respiratory issues from inhaling smoke, Ronaghi says. Inhaling high doses of PM2.5 can exacerbate symptoms, possibly leading to hospitalization. He recommends tending to your pulmonary health before wildfire season starts.

“The most important thing that you could do beforehand is staying up to date with your respiratory medications and your respiratory health,” Ronaghi says. “That means you're taking all your inhalers, getting your yearly flu vaccine, getting your pneumonia shot, and practicing your regular pulmonary health before the season.”

Protecting Your Overall Lung Health

People whose lungs are generally considered healthy should maintain healthy living practices, like exercising regularly and getting the annual flu shot to ensure a strong immune system.

If wildfire smoke does begin to affect the air where you live, consider checking the air quality often. On days of poor air quality, limit your time outside as much as possible and use air filtration systems to purify the air inside.

When going outside you should protect your lungs by using a face mask with N95 quality or better—Ronaghi says most surgical and cloth masks will not keep out the harmful PM2.5 particles. If you begin to experience respiratory difficulties, he says to seek medical attention sooner rather than later, as inhaling smoke will likely only progress your symptoms.

“It is very important to get this info out to the public so they can understand where the public health officials come from when we say, ‘stay indoors,’” Ronaghi says. “This can truly have long-lasting effects and can increase hospitalizations.”

3 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. Aguilera R, Corringham T, Gershunov A, Benmarhnia T. Wildfire smoke impacts respiratory health more than fine particles from other sources: observational evidence from Southern CaliforniaNat Commun. 2021;12(1). doi:10.1038/s41467-021-21708-0

  2. United States Environmental Protection Agency. Particulate matter (PM) pollution.

  3. Wegesser T, Pinkerton K, Last J. California wildfires: coarse and fine particulate matter toxicity. Environ Health Perspect. 2009;117(6):893-897. doi:10.1289/ehp.0800166

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.