Wildfire Smoke and Indoor Air Quality: Protecting Your DMV Home

The DMV area has experienced multiple wildfire smoke events in recent years, with smoke from Canadian and western US wildfires traveling thousands of miles to create hazardous air quality conditions in the DC metropolitan area. The June 2023 event turned DC skies orange and pushed the Air Quality Index into the "hazardous" range. These events are becoming more frequent and more severe due to changing climate patterns. While DMV residents cannot control when smoke arrives, they can prepare their homes and HVAC systems to provide clean indoor air during these increasingly common events.

Wildfire smoke particles are extremely fine, with most falling in the PM2.5 range of 2.5 microns or smaller. These tiny particles infiltrate homes through every available opening including door and window gaps, bathroom and kitchen exhaust vents, foundation cracks, and even electrical outlets on exterior walls. Your HVAC system can both help and hurt during smoke events. Fresh air intakes draw in smoke-laden outdoor air, while the system's filter provides your primary defense against circulating particles. The tightness of your home's building envelope determines how quickly outdoor smoke infiltrates your indoor space.

During a wildfire smoke event, set your HVAC system to recirculate mode if your system has this option, preventing it from drawing in outdoor air. Run the fan continuously on the ON setting to keep air circulating through your filter at all times. Close the outdoor fresh air damper if your system has one. Do not open windows or use whole-house fans, as these directly introduce smoke into your home. If your system lacks a recirculation option, running it normally with a high-quality filter still provides significant protection compared to no filtration at all.

Standard HVAC filters are not adequate for wildfire smoke particles. Upgrade to MERV 13 or higher during smoke events to capture the fine PM2.5 particles that constitute most wildfire smoke. If your system cannot handle MERV 13 filters due to airflow restrictions, use the highest MERV rating your system supports and supplement with portable HEPA air purifiers. True HEPA purifiers capture 99.97% of particles 0.3 microns and larger, making them highly effective against smoke. During extended smoke events, check and replace your HVAC filter more frequently as it will load up much faster than normal.

During severe smoke events, designate one room as your clean air room where you spend the most time. Choose a room with the fewest windows and exterior doors. Seal any gaps in windows and doors with towels or tape. Run a portable HEPA air purifier sized for the room. Keep the door closed to prevent contaminated air from the rest of the house from entering. This room serves as your retreat during the worst air quality periods, especially for family members with asthma, heart disease, or other conditions that make them especially vulnerable to smoke exposure.

After a smoke event passes and outdoor air quality returns to healthy levels, take steps to clear your home of residual smoke particles. Open windows and run your HVAC fan to flush out indoor air. Replace your HVAC filter, which will be heavily loaded with smoke particles. Vacuum all surfaces with a HEPA-filtered vacuum. Wipe down hard surfaces with damp cloths. Consider professional duct cleaning if the smoke event was prolonged or severe, as fine particles settle throughout your duct system and will be recirculated for months. DMV Air Pure provides comprehensive post-smoke event duct cleaning services. Call (800) 555-0199 to schedule service after the next smoke event.