Implications and Impacts of Mitigation Strategies for Wildland–Urban Interface Fire Smoke Exposure in Residential Environments

Abstract

This study examines the effectiveness of various indoor air quality pollutant mitigation strategies during Wildland–Urban Interface (WUI) fire smoke events. We simulated WUI fire smoke conditions in the field by burning mixed-fuel cribs designed as surrogates outside a test house and measured particle concentrations using multiple instruments inside the house. Increasing the number of deployed portable air cleaners provided a nonlinear benefit in particle removal effectiveness, with per-unit effectiveness increasing significantly when multiple units were operated simultaneously. Filters exposed to a single heavy smoke (Cpeak of 210 μg m–3 to 1300 μg m–3) loading showed no significant degradation in particle removal performance compared to new filters. The effectiveness of creating a “cleaner air space” within the test house was also evaluated, demonstrating substantial reductions in peak particle concentrations. Our findings emphasize the importance of accounting for air movement and mixing throughout a home when sizing and positioning air cleaners to ensure optimal performance. If internal doors are open and a central heating and cooling system is operating, air cleaners must be sized to the entire house volume, rather than just the room in which they are located. In contrast, if internal doors are closed and heating and cooling vents are sealed, a single properly sized air cleaner can provide a “cleaner air space” during WUI fire events.