In May, the National Oceanic and Atmospheric Administration wrote that “wildfire activity across the U.S. was below average,” with 337,182 acres burned. That all changed in June when about 50 fires set the West ablaze, and warm, dry conditions fanned the flames. (Check out Google’s U.S. Wildfire Crisis Map for updates on current fires.)
The U.S. Environmental Protection Agency says that smoke from fires is primarily composed of fine particle pollution from burning trees and other plants. The agency calculates the Air Quality Index, which gives real-time updates (with about a one-hour lag) about the levels of pollution in the air. It's a great source of information to determine if resuming outdoor activities is a good idea.
If you can’t get online before your workout, the state of Montana has developed the following air quality guide for areas affected by forest fires based on visibility range:
Visibility Range and Air Quality
13.4 miles and up: Good
8.8 to 13.3 miles: Moderate
5.1 to 8.7 miles: Unhealthy for sensitive groups
2.2 to 5.0 miles: Unhealthy
1.3 to 2.1 miles: Very unhealthy
1.3 miles or less: Hazardous
Finally, don’t trust a dust mask to protect you if your powers of visibility estimation are subpar. In addition to fine particles, wildfire smoke also contains a mixture of gases, including toxic carbon monxide, that the masks don’t filter out.
If you’re experiencing any irritation, such as a cough, or stinging eyes, it’s best to keep your workouts indoors in filtered air until the smoke clears.