3 Ways To Protect Your Home From Wildfire Smoke

The threat of more smoky air entering your home is likely to increase. Find out the best way to protect your family’s health.

The news about terrifying damage and loss of life from wildfires, including the latest round of fires in Hawaii, tends to focus on the fire itself and the immediate area. But as we all saw earlier in the summer, wildfire smoke can travel thousands of miles and cause discomfort and dangerous unhealthy conditions. 

While officials recommend staying indoors when the air is smoky and wearing a good quality N95 mask if you’re outdoors, the air inside buildings and homes can also become extremely polluted by smoke.

In the short-term, wildfire smoke can make you cough, make it harder to breathe, irritate your sinuses, sting your eyes and trigger an asthma attack, according to the CDC. Exposure can also worsen heart and lung conditions and damage your immune system.

Filters and air purifiers can improve your indoor air quality even when wildfire smoke is present and remove the microscopic particles that can get deep into your lungs. Here’s a three-step strategic guide for what to do, and when:

Step 1: Keep Smoke Outside

When you’re advised to stay indoors and keep your windows and doors closed, that should also trigger a warning to immediately shut off any Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs) in your home. These ventilators are great for pulling in fresh air to circulate throughout your home, but when the air outside is polluted, especially with dangerous wildfire smoke, you need to close them.

Make sure your windows and doors are well-caulked and sealed to keep smoky air outside. Some of the dangerous particulate matter from wildfire smoke can seep through even tiny gaps.

Researchers at the University of California, Berkeley, also found that using a kitchen or bathroom exhaust fan when wildfire smoke is present can pull some of the hazardous air into the house. They suggest limiting cooking on smoky days because of the gases and particulate matter generated by cooking that can’t be ventilated without letting more smoke into your house.

If you have a window unit air conditioner, Consumer Reports researchers recommend closing the outdoor air damper and sealing gaps between the window and the unit with weather stripping. If you have a fireplace, make sure the flue is closed to keep polluted air out. Keep the laundry room and bathroom doors closed because those spaces often have a duct that ventilates air outside. Switch your heating and air conditioning systems to “fan-on” mode to circulate the air within your home.

Be careful about vacuuming when wildfire smoke is present because it could send particles into the air. However, a vacuum with a HEPA filter can be used to trap smoke particles from your floors, according to Consumer Reports.

Step 2: Catch Particles with Filters

Once you’ve done everything you can to prevent smoky air from getting into your home, you can focus on filtering your air.

Upgrading your air filter is one of the most effective ways to keep wildfire smoke out of your home, says Mallory Micetich, a home expert at Angi, a platform for home improvement services and reviews. 

Not all air filters are created equal, Micetich points out.

“The MERV rating system can tell you how many particles are captured by different types of air filters,” Micetich says. “Air filters with higher MERV ratings capture more particles than air filters with lower MERV ratings, which leads to cleaner air.”

Basic filters that come with equipment are often rated at MERV 1 to 4, but if you live in an area affected by wildfire smoke, Micetich recommends that you opt for a MERV filter with a high rating to filter out as much smoke as possible.

“I recommend choosing a MERV 13 filter if possible, but anything MERV 8 or higher has the ability to filter out smoke,” she says. “Air filters come at various price points, but filters with high MERV ratings are usually more expensive than lower-MERV filters. I recommend buying your air filters in bulk for the best price.” 

High-rated MERV filters, it should be noted, can strain a heating and air conditioning system, so be sure to check with the manufacturer or a professional contractor,  to see if your equipment can handle a higher rated filter. Some filtration systems are designed to allow for better filters without impeding airflow. They do this by incorporating very thick filters that are like accordions. They essentially increas the square footage of filter medium this way, so air can flow through. 

Be advised, however, that, according to a New York Times’ Wirecutter column, filtering in smoky conditions can clog filters quickly cutting recommended replacement times in half. They also suggest replacing filters once the smoke has dissipated.

Washable filters are more economical than disposable ones since they only need to be purchased once–and they’re better for the environment, too. The important element in choosing a reusable filter, just like with a disposable one, is the MERV rating. Some manufacturers sell washable filters with a MERV 13 rating, but many fall in the MERV 1 to MERV 4 range.

While you can’t instantly add a whole-house filtration system in the midst of a wildfire season, whole-house air filtration is an efficient and effective way to clean the air in your home, Micetich says.

“If you have a whole-house HVAC system, I strongly recommend adding a high-quality filter to keep your air as clean as possible,” she says. “If you don’t have an HVAC system, you can add portable air cleaners to your home instead. Make sure you use high-quality HEPA filters in your air purifiers for the best results.”

Step 3: Purify Your Air

Air purifiers take cleaning your air one step further by removing pollutants with the help of a HEPA filter. One study tested portable HEPA air cleaners and found they lowered indoor PM2.5 from wildfire smoke by 57-85%

Air purifiers with a HEPA filter can cost from $50 to more than $1,000, according to Consumer Reports, but their highest rated air purifiers start at $250.

If you’re in the market for an air purifier to reduce the impact of wildfire smoke but don’t have the budget for a highly rated air purifier, you can DIY an effective air purifier for less than $50, according to the Berkeley researchers. You’ll need a box fan, duct tape and five MERV 13 air filters.

At The Sonders Project, AprilAire will feature Carbon MERV 13 air filters for high-efficiency air filtration and purification, making smoke a problem of the past for homeowners. In addition, because of the dry conditions in Colorado, AprilAire will include steam humidifiers to keep IAQ at optimum levels. 

Recommended Air Purifiers 

Consumer Reports’ highly recommended air purifiers to combat wildfire smoke include:

Blueair BluePure 211+, which is priced at approximately $250 to $320 and works for rooms up to 635 square feet.

Alen BreatheSmart 75i Pure, which is priced at about $750, is Consumer Report’s best overall pick.

Coway Air Mega ProX, which is priced at approximately $1,000, and covers more than 2,000 square feet.

You’ll need to choose the right size air purifier for your home and for each room where you use one. Ideally, you’ll want an air purifier designed for a larger space than yours to make sure it’s effective, according to Consumer Reports. Their research found that purifiers designed for rooms larger than 350 square feet are better at removing smoke than those designed for rooms smaller than 150 square feet.

Placement of air purifiers is also important. The Berkeley researchers recommend placing one in your bedroom and keeping the door closed so that your air is as clean as possible while you sleep.

Consumer Reports also recommends buying an air purifier with a carbon filter to eliminate the smell of smoke in your home. Keep the air purifier running constantly and be sure to change the HEPA filter when an indicator light turns on or on a schedule recommended by the manufacturer.

While clean air is especially important when smoke is present, these steps and systems work during any period with poor air quality.

Here are some academic studies comparing filtration methods for removing wildfire smoke indoors:

This study tested portable HEPA air cleaners and found they lowered indoor PM2.5 from wildfire smoke by 57-85%

In summary, research indicates that a layered approach combining HEPA-based filtration in HVAC systems and portable air cleaners with additional localized exhaust filtration provides optimal protection by capturing both particles and gases. Proper sealing to avoid filter bypasses is also critical.

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