by Colleen E. Reid, Associate Professor of Geography, University of Colorado Boulder
Wildfire smoke from fires burning in Canada and northern Minnesota has been pouring across the Great Lakes and northeastern U.S. states, turning skies an eerie shade of orange. In the West, smoke has also been spreading into communities in Colorado and neighboring states as more wildfires burn in hot, dry conditions in July 2026.
Wildfire smoke is a complex mixture that includes nitrogen oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, carbon monoxide, carbon dioxide and particulate matter. When homes or buildings also burn, they can release an even more toxic stew of chemicals from burning electronics, furniture, plastics, paints and much more.
What you see when you see a smoke plume or when the air is hazy with wildfire smoke are the tiny particles that are too small to fall to the ground on their own — known as PM2.5 — that can travel deep into the lungs and even enter the bloodstream. Breathing wildfire smoke has been associated with a higher risk of preterm births and other issues during pregnancy, and potentially cardiovascular problems such as heart attacks and strokes, although the evidence for these effects is more mixed. The longer-term health effects of wildfire smoke are less clear, but it is a growing area of research.
The first thing to do to protect yourself from wildfire smoke is to know how bad the smoke is and how long it is going to last. One great place to get information for where you live on current wildfire smoke is fire.airnow.gov. You can zoom in on the map to where you live and find color-coded circles reflecting data from both U.S. EPA air-quality monitors and PurpleAir sensors that people have put in their homes. The colors show the level of PM2.5 at that location and suggest the associated health risk.
To find out how wildfire smoke is expected to change over time in North America, you can look at maps from FireSmoke Canada and the U.S. Interagency Wildland Fire Air Quality Response Program.
Depending on the level of the health risk, steps to protect yourself can include staying indoors with windows closed, using a portable air purifier with a HEPA filter, wearing a well-fitting N95 or KN95 mask outdoors, and avoiding strenuous outdoor activity until air quality improves.
This article is republished from The Conversation under a Creative Commons license.
