Our hearts go out to those who have lost their lives and property in the wildfires raging in southern California and beyond. Even people whose homes weren’t directly damaged by fire may face health risks from air pollution both outdoors and indoors. In this article we cover some of the risks of wildfire smoke and provide some recommendations for minimizing exposures.
The Risks of Wildfire Smoke
Wildfire smoke is a complex mixture of particles and gases with the exact constituents being heavily influenced by the materials being burned. In a dense urban area, the constituents of the smoke will be more reflective of house fires rather than wildfires. That means the smoke will contain the chemical markers of burnt plastic and other hydrocarbons, such as dioxins and furans. Other chemical associated with fires include benzene, acrolein, and polycyclic aromatic hydrocarbons (PAHs). When buildings with asbestos or heavy metals such as lead go up in flames, those hazards may become part of the smoke that spreads beyond property lines. In fact, outdoor air quality monitors in Los Angeles picked up elevated levels of lead, chlorine, and bromine.
Beyond chemicals, there are serious concerns about the particles in wildfire smoke. In the Environmental Protection Agency’s (EPA) publication, Health Effects Attributed to Wildfire Smoke, they highlight the following deleterious effects caused by particle pollution:
- Respiratory symptoms (coughing, wheezing, difficulty breathing)
- Respiratory effects (bronchitis, increased asthma exacerbation)
- Cardiovascular effects (heart failure, heart attack, stroke)
To see the current status of wildfire smoke and air quality in your area, you can reference AirNow’s Fire and Smoke Map. AirNow is a partnership between multiple government agencies including the EPA and the National Oceanic and Atmospheric Administration (NOAA).
Protecting Your Home
I was the expert interviewed for the Vox article, “How to make your indoor air better when it’s smoky outside”. There and here, I will try to simplify the advice which can quickly get complicated based on the unique attributes of the building and its heating, ventilating, and air-conditioning (HVAC) system.
Step One: If your HVAC system brings in outdoor air, turn it off during peak times of outdoor air pollution. Under normal conditions, that outdoor air is helpful because it is likely to have lower levels of air pollutants. But in the midst of wildfires, the outdoor air quality will be significantly worse than indoor air quality, so we want to minimize the HVAC system from bringing in that outdoor air. That may mean manually closing an outdoor air intake or turning off controls that open outdoor air dampers.
Step Two: Minimize the opening of doors and windows and seal any large gaps. This advice is probably obvious, but it is important to reduce the pathways that outdoor air pollution can travel inward.
Step Three: Minimize the use of exhaust fans. Only use exhaust fans sparingly, if at all. If you think an activity indoors, such as stir-frying on a stove, is generating more pollutants than what is found in the outdoor air, go ahead and run the exhaust fan briefly. But exhaust fans create negative pressure and pull in more outdoor smoke, so their use should be minimized during peak wildfire smoke.
Step Four: Operate a portable air cleaner. Portable air cleaners (PACs) come in many sizes and varying technologies. Generally, the best PACs use high efficiency particulate air (HEPA) filters, which remove 99.97% of particle pollution. Some PACs also include activated carbon to help remove gases and VOCs, which can be helpful during wildfires. PACs using other technologies such as ionizers, ozone, hydroxyl radicals, and chemical release may introduce new hazards so be cautious about using these technologies. If money is a concern, you can build a DIY Corsi-Rosenthal Box.
To help supplement your PAC, you can run your HVAC system continuously to benefit from the centralized filters. Just make sure you have a minimum of MERV 11 efficiency filters and that the system isn’t bring in outdoor air (see Step One).
Personal Protection
As a last line of defense, you can consider wearing a respirator to reduce your exposure to air pollution. Cloth and surgical masks will offer a little protection, but you need a respirator, such as a disposable “N95”. An N95 is a respirator that is constructed from filtration material that removes a minimum of 95% of particle pollution of all sizes. Getting a tight fit is key to properly wearing an N95. Make sure to use both straps without criss-crossing them and utilize the nose clip to help it better conform to your face.
For most people, an N95 respirator is a good starting point however, N95s only remove particles, not gases associated with fires and smoke. For that, you’ll need a half-face or full-face respirator with cartridges specific to the gases of concern. Even then, there isn’t a perfect solution that offers protection from all wildfire contaminants like carbon monoxide, chlorine, and bromine. Opting for a more protective solution can be beneficial however, there are a couple watch-outs including:
- More restrictive breathing – more protective respirators may present breathing challenges for respiratory compromised individuals
- Proper replacement schedule is essential – N95s are typically single use but half-face and full-face respirators have replaceable cartridges. Knowing when to replace them can be challenging.
If you want to consider a disposable respirator (technically called a “filtering facepiece”) that offers more protection than an N95, look for a P100. A P100 uses a filter that is 99.97% efficient for removing airborne particles including asbestos, fiberglass dust, lead dust and more. A P100 disposable respirator with a release valve can be helpful to reduce labored breathing.
If you want more protection vs. a disposable P100 you can use a full or half face respirator with replaceable cartridges. Combination cartridges (e.g. 3M 60923, 60926) can provide more defense against organic vapors and acid gasses vs. a disposable P100. It is important to note however, that no respirator offers protection from carbon monoxide and all wildfire contaminants.
Conclusions
If you are in a region experiencing wild fires, there are many hazards to be concerned about in your indoor and outdoor air. Follow our four steps to achieve the best possible indoor air quality and consider using a minimum of an N95 respirator to supplement.
Reach out to Indoor Science to schedule an educational webinar, respirator fit testing or learn more about our environmental testing services. We can be reached at (312)920-9393 or [email protected].