Across the globe, wildfires seem to be out of control. The number of significant wildfire events, the frequency with which they occur and the amount of people they impact all continue to rise due to climate instability. While you likely know that wildfire smoke exposure presents significant health risks for you and your family; it’s also important to realize that wildfire smoke impacts not only outdoor air—but indoor air quality too. Take the time now to better understand wildfire air quality and how to prevent smoke exposure in your indoor space.
Wildfires are a significant threat. Wildfire events continue to impact a greater number of people and communities across the United States. Historically, wildfire season was a distinguishable period of time. Many associated disastrous wildfires with the Western and Southwestern regions. But the past few decades changed those associations, as the when and where wildfires are likely to occur shifted.
And while many associate wildfires with summertime, actual wildfire season is simply the period between the first and last big wildfires of the year. Meaning—really any time of year. Climate change, extreme heat and weather have made wildfires more unpredictable. The number of annual wildfires has roughly tripled since the 1970s. And the late 2010s saw numerous record-breaking wildfire events. Just check out this yearly breakdown of fire season in California over the past decade. The start and end dates cover a vast range making wildfires a true year-round threat.
Do Wildfires Cause Air Pollution?
The answer to this question is 100 percent, absolutely yes. Wildfires worsen air quality because of both the chemicals and particles emitted from combustion (AKA the literal fire) as well as the combustion byproducts. A reality only worsened by the fact that combustion is made up of natural biomass materials and human-made materials. Translation: there is a lot of junk in wildfire smoke.
It also doesn’t help that wildfire smoke travels far and can persist for days, weeks, even months after an event. The threat of wildfire smoke affects those near and far. AirNow’s real-time fire and smoke map is a helpful resource.
Wildfire smoke is quite the mixture. Various pollutants found in wildfire smoke include particulate matter, hydrocarbons, nitrogen oxides, carbon dioxide, carbon monoxide, organic chemicals and more. Again—it depends on what exactly is burning, but the chemicals and pollutants found in wildfire smoke can number in the thousands. All of the lesser known air toxics or hazardous air pollutants are still significant respiratory irritants.
Pollutants also go through atmospheric reactions, resulting in dangerous secondary pollutants like ground-level ozone. Ozone, particulate matter and carbon monoxide are the pollutants most tracked during wildfires. Partly because they are criteria pollutants, meaning the Environmental Protection Agency (EPA) sets standard ambient levels acceptable for health (NAAQS). And, partly because widespread air quality monitoring is available for criteria pollutants.
Health Effects of Wildfire Smoke Exposure
In addition to the danger of actual wildfires, wildfire smoke in particular presents considerable human health risks. Particulate matter, also referred to as particle pollution, is the greatest health threat found in wildfire smoke. Short-term particulate matter exposure can result in eye, ear, throat and nose irritation, reduced lung function and lung inflammation, persistent cough, phlegm or wheezing, difficulty breathing, bronchitis, worsening lung diseases, asthma and COPD, worsening cardiovascular diseases and increased risk of premature death. Clearly, it is not something you want to be breathing often. Yet, roughly 90% of total wildfire smoke emissions consists of fine particulate matter.
And, because wildfire smoke acts as a lung irritant, exposure can make you more prone to other respiratory infections. This is especially true for more sensitive and vulnerable groups. People with pre-existing health conditions, children, older adults, pregnant women, outdoor laborers and low-socioeconomic households are all at a higher health risk from wildfire smoke exposure. For the most part, average healthy adults can and will recover from wildfire smoke exposure unharmed. Nevertheless, it’s important to keep in mind how smoke inhalation impacts certain persons differently. Children in particular can present significant respiratory issues because of their smaller airways—even if the same exposure level is a minimal issue for adults.
There is less research on the long-term health effects of wildfire smoke exposure, or experiencing consecutive wildfire events. While some studies do show greater health risks, focusing your preventive efforts on the short-term is not a bad plan. How to do it? Intervening in your home for safer, healthier indoor air.
Stay Indoors: How To Improve Indoor Air Quality During a Wildfire Event
Staying inside is the go-to health recommendation during a wildfire. However, staying indoors as an effective strategy only works if your home is set up for good indoor air quality. The key is to limit exposure. That means minimizing how much smoke can enter your indoor space and minimizing indoor pollution sources. There are a number of ways to go about limiting your exposure to wildfire smoke indoors.
1. Correct Air Conditioning Use
This looks different depending on your home’s AC system.
Put simply, central AC should be set to recirculate only and ran continuously during a wildfire. Contrary to popular belief, air-conditioners do not bring outside air in. They simply circulate and cool air already present in the home. (Yes, in a non-wildfire event, that is not the best scenario for indoor air quality. But when wildfire smoke is present, recirculation is ideal.)
To allow for the most filtration possible, run your home’s AC or HVAC fan continuously. That way, the air supply is constantly moving through the air filter and reducing pollutant levels. Newer AC models and systems offer a fresh air intake option. Make sure to turn any fresh air setting off and opt for recirculation.
Window AC Unit
Make sure your window AC unit is installed correctly. Check for a tight seal to limit possible infiltration. Also, either switch the setting to recirculation or physically close the outdoor air damper.
Portable AC Unit
If your portable AC unit uses two hoses, check for a tight seal between the window and vent. If your portable AC unit only has one hose, do not use it (or significantly limit its use) during a wildfire.
For those without any type of air conditioning system at home, the general consensus is to go elsewhere during a wildfire. Official public health recommendations will often include staying with friends or family, particularly for those without AC. The sad truth is that during wildfires, in homes without AC, indoor particulate matter concentrations reach roughly 50% of outdoor levels. That’s even with windows and doors closed.
2. Ventilation Do’s and Don’ts
Refrain from natural ventilation (AKA opening windows and/or doors) during a wildfire. If your HVAC system includes mechanical ventilation, such as an ERV or HRV, turn off these fresh air systems to prevent wildfire smoke from entering your space.
Of course, reducing ventilation to limit smoke exposure is quite the IAQ Catch-22. The health benefits of remaining indoors with minimal incoming smoky outdoor air are worth it. Still, indoor pollution is a reality. So whenever there are small periods of cleaner outdoor air or improved air quality index (AQI) ratings during a wildfire, make sure to air out your home.
3. Reduce Indoor Pollution Sources
Healthy home habits and general source control methods are crucial when overall air quality is poor. Limit vacuuming which can kick up pollutants—unless you have a HEPA filter vacuum. Make sure appliances vent outdoors. Do not burn candles, incense or anything of the like.
4. Consider Creating a Clean Room
A clean room likely seems intense. But its incredibly beneficial for those in high-risk wildfire areas as well as outdoor workers unable to escape wildfire smoke in the day, and those worried about pre-existing health conditions.
Choose a room with minimal windows and doors and without a fireplace—an interior room. Keep windows and doors closed at all times. Use a portable room air cleaner and run it continuously.
5. Air Cleaners
For air cleaning, first and foremost, upgrade your home air filter. Use the highest air filtration level possible that works with your home HVAC system. Our suggestion is a MERV-13.
Another air cleaning option is to invest in an air purifier. Want a portable unit? Opt for an air cleaner with HEPA level filtration. Want to purify the entire house? Opt for a whole-home active air purifier.
When you can’t stay inside, make smart outdoor decisions. After all, these IAQ tips and strategies work best in tandem with minimal outside exposure. That might look like limiting outdoor exercise or physical activity, using a face mask or respirator, planning outings and necessary trips during less smoky periods of the day or regularly checking your local AQI.
Preparation Is Key
In the end, the public health perspective is to prepare for wildfires. The absolute key to stay safe is preventive measures. Taking action before the record-breaking wildfire occurs. Researching air quality upgrades and consulting and HVAC contractor before wildfire smoke is at your doorstep. For your and your family’s health and safety, consider investing in your home’s indoor air quality today. Don’t wait! Have a plan in place and improved IAQ at the ready.