How Do Wildfires Affect Indoor Air Quality?

Americans spend roughly 20 to 22 hours of their day indoors, and news of summer wildfires can send everyone inside even more frequently. Yet the damage done by wildfires to the quality of the air cannot be easily escaped by sealing windows, closing doors, and turning on the air conditioner.

Indoor air pollution threatens the health and livelihood of many Southern Californians, who may be aware of the omnipresent air quality problem but unsure of the true risk it presents or how to ensure the health of family members, friends, and neighbors.

Where There’s Smoke, There’s…

Common sense dictates that wildfires produce pollutants, but did you know that they produce carbon monoxide, acetaldehyde, benzene, and even formaldehyde as part of their noxious makeup? These and other gaseous pollutants spread over thousands of square miles during the wildfires common to the Western U.S. and especially Southern California.

Of further concern is particulate matter, defined as solid particles and liquid droplets suspended in smoke. Particulate matter can irritate the mouth, nose, and eyes, and very fine particulate matter, like that found in smoke, can be inhaled into the deepest recesses of the lungs. Countless research has indicated that airborne particulate matter increases by several factors during wildfire season.

Climate change has also accelerated the likelihood and severity of wildfires. One estimate suggested a 54% increase in the average burned area by 2050, and the average outdoor level of fine particles will increase by 30 to 40 percent. California is particularly affected because of Santa Ana winds, which reverse typical flow patterns by blowing toward the coast from inland areas, sending flames and smoke plumes from mountainous fires toward coastal cities and towns.

The Health Effects of Smoke

What effects does wildfire smoke have on the body? Increased incidences of bronchitis, pneumonia, and other respiratory infections, eye and nose symptoms, inflammatory concerns, a statistically significant increase in respiratory morbidity, and even premature death have all been tracked alongside exposure to wildfire smoke. Wheezing, phlegm production, coughing, and light-headedness are all common minor reactions to smoke exposure.

As with many other outdoor health concerns, the very young, pregnant women, the elderly, and people with pre-existing respiratory ailments are more susceptible to the effects of wildfire smoke. People who have asthma or suffer from COPD should be especially aware of days of high ozone or high pollution.

Staying Inside

While the effects of wildfires on air quality have been well-established, you might be tempted to believe that a simple solution is to limit outside activities during high-risk days. Though that is sound advice, the comforts of your home might bestow a false confidence. Indoor air pollution should still register as a primary concern each fire season.

Windows Up

Homes with low or no filtration systems will only find their airborne particles reduced by about one-half or as little as one-quarter; homes that utilize open windows instead of central air might see as little as a 5% reduction in air pollution versus the outdoors. Even homeowners in California who close their windows and rely on central air conditioning still see only a two-thirds reduction in particle concentrations. A helpful tip is to seal off window frames and door casings to prevent harmful pollution from seeping into a home (and forcing filtration systems to work harder). Trained technicians can quickly demonstrate areas of air leakage.

Available Appliances

Beyond staying inside with windows shut and fans on, residents of fire-prone areas can improve the air quality of their homes by installing forced-air cooling systems with high-efficiency particle removal filters and portable fan-filter systems (particle air cleaners). Be sure your air filters are cleaned regularly and are not made of low-efficiency fiberglass; strive for a pleated high-efficiency particle filter. During periods of intense or frequent wildfires, filters may need to be replaced each month. Stock up on extra filters – preferably at a rating of MERV 8 or higher – ahead of peak wildfire season, especially if your household has susceptible occupants.

Window-based air conditioning units typically do not filter the air well or at all, so be aware of family members or neighbors who may be reliant on these appliances to cool their homes. If they are the only option, be sure to check that the settings are on re-circulated air as opposed to drawing air in from the outside. Humidifiers and dehumidifiers do nearly nothing to reduce air pollution and should not be relied upon in the event of a wildfire.

Air-Filtration Units

Upgraded cleaning systems have the potential to effectively scrub the air to almost wholly free of particulate matter and thereby reduce preventable illnesses and hospital stays. Charcoal pre-filters can greatly assist in reducing odor, and true High-Efficiency Particulate Air (HEPA) filters are excellent and affordable options. Consider the cost of air-filtration systems versus even a single overnight visit to the hospital, let alone chronic admittance. The healthful effects provided by properly installed and cleaned filtration systems are multiplied for homes with infants and elderly people.

Air-filtration units can be compared by researching airflow rates and removal efficiency or Clean Air Delivery Rates (CADR). The CADR is a handy tool for combining airflow and efficiency. Also consider the size of the room being filtered. A cleaning unit should filter two to three times the room volume each hour; room volume is computed by multiplying the floor dimensions by the average height of the ceiling. Whichever unit you choose, be aware that some air cleaners produce ozone, which exacerbates existing climate issues and is harmful to your health. The California EPA Air Resources Board has a list of certified devices to help avoid ozone-generating types of air-filtration appliances.

Further Resources

The Air Pollution Control District provides daily updates for San Diego County, with color-coded levels of health concern and primary pollutants to watch, including ozone and particulate matter. The EPA’s AirNow website utilizes the NowCast methodology to provide hourly pollution monitoring across the nation, accounting for various environmental factors to update the public. The U.S. Environmental Protection Agency provides generally helpful tips on how to prepare for a wildfire.

How likely are you now to use an air-filtration device to reduce your indoor air pollution? Talk to us in the comments section!