Hazy, smoke-filled skies from large wildfires burning throughout California, Montana and across the Canadian border in British Columbia are causing poor air quality and health concerns.
Officials have issued unhealthy air quality and smoke warnings in California, Washington, Oregon and Montana.
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Here is some advice for reducing your exposure risk and keeping yourself and your family safe.
Why wildfire smoke makes you sick
Wildfire smoke includes particles from burning vegetation and building materials mixed with gases. If your eyes feel like they're stinging, smoke exposure could also be inflicting other damage. Particles could be getting into your respiratory system.
Exposure can cause chest pain, a fast heartbeat or wheezing or bring on an asthma attack. Besides coughing and trouble breathing, many people experience symptoms similar to a sinus infection, such as headaches, sore throat, a runny nose and even tiredness, according to the CDC.
Wildfire smoke can be especially harmful to the elderly, pregnant women, children and those with chronic heart and lung diseases. Because children breathe more air per pound of body weight than adults and their airways are still developing, they may experience more severe symptoms.
Those with asthma or lung disease should consult their doctors about navigating situations like this. Some people may even experience illnesses like bronchitis due to the fine particles, according to the Environmental Protection Agency.
Staying healthy when it's smoky
If you see a haze, smell smoke or know of a wildfire in your area or a place you plan to visit, check the Air Quality Index to see whether you need to limit your time outdoors.
When advised to stay inside, keep your windows and doors closed. It's OK to keep the air conditioner running, but make sure the filter is clean, and close the fresh-air intake to prevent smoke from entering, according to the CDC.
It's also important to keep indoor air clean by not burning candles, using the fireplace or gas stoves, or smoking. Running a vacuum can also keep particles circulating in the air.
Dust masks actually trap large particles and don't protect your lungs from smoke inhalation, but a mask that uses a filtering respirator can offer some protection. The CDC also has tips for how effective different types of masks can be, depending on your exposure.
Even if the air outside or in your home looks clear, it may not be free of harmful microscopic particles, especially if the wildfires and smoke persist for weeks.
Pediatric pulmonologists at Children's Hospital Colorado's Breathing Institute also recommend changing your clothes if you've been outside, rinsing out red, irritated eyes and drinking fluids to keep from being dehydrated. Parents should seek emergency care for their children if they experience real difficulty breathing or a change in their level of consciousness.
There is a low risk of long-term effects of wildfire smoke exposure for healthy individuals.