Wildfire Smoke Challenges for HVAC Filter Media Efficiency

TANYA SHIRMAN, Sissi Liu, VP of Materials

     Abstract Number: 65
     Working Group: Burning Questions of Aerosol Emissions, Chemistry, and Impacts from Wildland-Urban Interface (WUI) Fires

Abstract
As climate change drives more frequent and intense wildfires, maintaining indoor air quality (IAQ) is increasingly vital for occupant health and safety. Yet, the performance of HVAC filter media against wildfire smoke remains underexplored.

In this study, we evaluate the time-resolved, size-specific filtration efficiency of 17 commercial HVAC filter media—spanning charged and uncharged synthetics, composite nanofibers, and fiberglass—using smoke generated from pine needles as a proxy for wildfire smoke. Testing was conducted in a controlled laboratory setup that enabled realistic exposure to smoke particles from biomass combustion.

Our results reveal significant variation in filtration efficiency across media types. Scanning electron microscopy (SEM) analyses further illuminate how smoke particle morphology and deposition patterns contribute to performance degradation over time.

These findings expose critical gaps in current filter testing standards, which emphasize inorganic particles and overlook the complex behavior of smoke. We propose the development of targeted testing protocols and performance metrics to better assess and improve filter media efficacy in wildfire smoke scenarios.