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Smoke from wildfires can cross regional and international borders, affecting faraway communities. This hazard can remain in your neighborhood’s air indefinitely. Find out how long the wildfire smoke will last and what you can do to keep your home safe from the pollution.
An active wildfire is probably the reason why there’s smoke in the air near you, even if it doesn’t smell like burning wood.
Smoke from forest fires changes in smell over distance. The farther you are from the source, the more you’re likely to smell burning chemicals. Ultraviolet radiation from the sun breaks down the aroma of campfire smoke, leaving behind harsher and more stable contaminants.
Seeing or smelling smoke doesn’t necessarily mean that your house is at risk of getting burned, though. It can travel thousands of miles, as happened during the 2026 Canadian wildfires. The pollutant triggered air quality alerts as far as North Carolina at one point.
Moreover, the smoke you see or smell in the air near you may just be the result of outdoor burning. Open fires are highly regulated but not universally banned in the United States. Their legality varies by jurisdiction.
For instance, recreational, residential and land clearing fires require a permit within Island, San Juan, Skagit and Whatcom counties in Washington state. The Northwest Clean Air Agency can call burn bans due to impaired air quality.
Smoke will last as long as the corresponding wildfire is active. Burn time depends on fuel topography, fuel availability and weather conditions.
The wildfires that last the longest tend to be in areas that have dense vegetation consisting of grass, leaves and twigs, move uphill, get dry air day and night and experience high winds.
Nobody can tell how long an active wildfire will last. However, historical data from the U.S. Department of Agriculture Climate Hubs shows that the average burn time of individual fires increased from six days between ‘73 and ‘82 to 52 days between ‘03 and ‘12.
Keeping your home’s indoor air quality healthy enough to breathe in when wildfire smoke has reached your area can be challenging, but doable. Here’s how you can keep smoke out of your house.
Smoke is a fluid, so it travels through the air. Therefore, the most effective way to prevent it from entering your indoor living spaces is to ensure your property’s building envelope is airtight.
Energy auditors perform a blower door test to uncover all pockets of heat loss, including air leaks. Hiring one is the most effective way to determine how airtight your space is and how to address gaps and openings.
A 2021 EPA-funded study found that 43.9% of Americans leave at least one window open the day before the national survey. The frequency of door opening was about half that of window opening. People seem to open one or more windows longer and more frequently to cool the indoor space. It peaks when the outside temperature reaches the range of 18° to 21° Celsius, or about 64° to 69° Fahrenheit.
If you’re one of them, you may have to rely on mechanical ventilation until air quality in your area improves. Be vigilant about wildfire smoke, as it quickly pollutes your space through these entry points.
The risk of indoor air contamination is a good reason to get your drafty windows and doors fixed sooner rather than later. When buying new windows, check the energy performance ratings. Pay attention to Air Leakage, which measures how quickly air passes through joints in the unit. Ranging from 0.10 to 0.30, a lower value means a more airtight.
Running your HVAC system with the intakes open when there’s wildfire smoke would worsen your indoor air quality rather than expel pollutants outside.
If your central heating and cooling equipment has a fresh-air intake, set it to “recirculate” mode or figure out how to close the inlet. If you have a window air conditioner, close the outside air damper or use alternative cooling methods, such as fans, for the time being.
If you have an evaporative cooler, cover its outside air intakes with thicker filters only if you can access them safely. Otherwise, use fans and other cooling methods to avoid inadvertently bringing the smoke inside.
Preventing wildfire smoke from entering is one thing. Dealing with the particulates and harmful gases that manage to get in is another. Here’s how you can remove the pollutants inside the house.
You should get a filter with a Minimum Efficiency Reporting Value of 13 or higher to capture most microscopic solid particles. Fine particulate matter is more dangerous to inhale than volatile organic compounds (VOCs), though the latter stinks.
These machines use multiple stages of filtration to capture specific contaminants in indoor air. Models equipped with activated carbon can target VOCs. They complement HVAC units that rely solely on standard high-efficiency filters. Air cleaners are effective only in the rooms they’re in. Use them where you spend most of your time.
You may benefit from wearing the N95 while waiting for your air cleaners to purify the air. This respirator can filter out airborne particles, but not gases. Ensure a tight seal that covers your nose and mouth to ensure it works properly. The CDC warns that wearing one can make it harder to breathe and trigger a natural rubber latex allergic reaction, so consult your doctor first.
Keeping your house habitable when the indoor air quality in your area is poor is a tall order. Foresight, vigilance and expeditiousness can mitigate the impact of wildfire smoke on your home lifestyle. Still, these precautions aren’t a substitute for emergency evacuations. When local authorities recommend seeking shelter somewhere safer, heed their advice to the best you can for your respiratory and mental health.
