An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

The Danger of Wildland Fire Smoke to Public Health

Published January 30, 2018

As the 2017 wildfires in California, Oregon, and other western states revealed, smoke from wildfires is harmful to health. Many residents near the fires experienced respiratory distress and other health problems from breathing in toxic smoke for days and weeks during some of the fires.

Wildfires are increasing in intensity and size, contributing to impaired air quality for people living near or downwind of the fires. But while smoke from wildfires is a threat to health, and even survival in some cases, there are many unknowns about the health effects of smoke from wildfires as well as prescribed fires. Is all smoke the same or is some more toxic than others based on the type of trees and vegetation burned? What are the health effects from smoke in the flaming stage of a wildfire, compared to the smoldering stage? How does smoke “age” over time and are the health effects different? And who is most susceptible?

One of the main components of smoke is particle pollution (PM), which is a regulated air pollutant. Wildland fires, which include wildfires and prescribed fires) now account for 40 percent of the total PM emitted in the country, making it a major source of the pollutant, which causes lung and health problems.

While smoke from wildland fires is a recognized public health threat, there are very few studies that examine the specific role of the different components of smoke on disease and the severity of disease when people are exposed, says EPA’s Dr. Wayne Cascio, Director of the National Health and Environmental Effects Laboratory, in an article titled, “Wildland Fire Smoke and Human Health,”Exit published in the December 2017 issue of Science of the Total Environment.

The increase in wildfires in the U.S. and worldwide makes it important to learn more about the health impacts on people living in smoke-prone areas as well as those who live farther away but still downwind of the smoke, Cascio says.  The study of health effects from wildland fires is a relatively new and quickly expanding field of study, he notes. The article provides insights into the state of knowledge of what we know about a growing public health concern and describes needed research.  

One area of investigation where more studies are needed is to determine what smoke emissions do to impact the cardiovascular system. While the association between PM and heart problems is well documented in the scientific literature, there have been mixed results in a small number of studies about the impacts on the cardiovascular system, Cascio states in the article.

There is also an interest in learning what the effects might be for a few days of exposure compared to weeks or even months as the length of time for extinguishing wildfires can put people in the path of smoke for a long time. Short-term and long-term health studies are needed, says Cascio. In the article, Cascio also encourages policy decision makers at all government levels, public health professionals, and air quality managers to explore ways to improve communications and outreach about the threat of exposure to wildland fires.

More research on wildland fires can help officials to identify those most at risk from smoke exposure and provide guidance on effective public actions to decrease exposure, reducing health problems and lower the number of visits to the doctor’s office or hospital during a wildland fire.   EPA scientists are working with states, communities and tribes to provide this research.   

Learn more about EPA’s Wildland Fire Research