This week, wildfire smoke from Canada and a plume of desert dust are affecting air quality levels across many parts of the United States. When the air is smoky, it’s important to consider whether it’s safe to exercise outdoors — and how to protect yourself if you choose to head out.

There is very little research on the health effects of short-term exposure to wildfire smoke, including during exercise. So, when estimating what the smoke does to the body, there aren’t always clear answers, said Dr. Michael Koehle, a kinesiologist at the University of British Columbia who studies the interaction between environmental pollution and exercise.

Still, based on what we know about the kinds of particles found in wildfire smoke and their potential health effects, experts say it’s important to monitor air quality and, when conditions are bad, to avoid outdoor workouts or keep them short.

Individuals who may be more sensitive to the effects of smoke should be especially careful — including children, older adults and those who are pregnant or have underlying lung or cardiovascular conditions such as asthma, chronic obstructive pulmonary disease or heart disease, said Dr. Stephanie Christenson, a pulmonologist at the University of California, San Francisco School of Medicine.

As the climate changes, wildfire season is getting longer and affecting more regions of the United States. Here’s what you need to know to stay safe.