But anyone can feel the effects of wildfire smoke. Inhaling it can immediately cause coughing and wheezing, a headache, stinging eyes, a scratchy throat, sinus irritation, chest pain, a rapid heartbeat and fatigue.

Consider wearing a mask.

You should stay inside as much as possible, particularly if you are at higher risk of illness. If you need to go outside, wear a high-quality, tightfitting mask, like an N95. This can help filter out tiny particles from the smoke, said Laura Corlin, an associate professor of public health and community medicine at Tufts University School of Medicine.

Seal off your home.

If you’re able to stay inside, “you definitely want to try to make your indoor environment as smoke free as possible,” said Dr. Corlin. That means making sure windows are tightly shut. Run an air purifier if you have one. If you do not, turning on the air conditioning can help. But if you have a central air system that takes in air from outside, close the outside air damper, or switch the system to recirculate mode, so that you are not pulling air that is tainted with smoke into your home. While less effective than air conditioning, fans can also be useful in circulating air — turn them onto their highest setting.

Know the signs of heat-related illness.

Excessive heat could potentially worsen the effects of wildfire smoke in some high-risk individuals, and also carries its own health risks. It’s critical to stay hydrated, Dr. Corlin stressed. To cool down quickly, you can also apply some water to your wrists or the back of your neck. Watch out for signs of heat stroke, which include a body temperature of 103 degrees or higher, dizziness, headaches, nausea, confusion, fainting and red, dry or damp skin. If you or someone near you experiences those symptoms, seek medical attention immediately.

Monitor your health in the days after.

Some complications from wildfire smoke can take several days to emerge, Dr. Corlin said, including heart issues and strokes. Stay alert to possible problems for a week or so after you are exposed, paying particular attention to any symptoms like chest pain or an elevated heart rate.