Impacts of Aging and Relative Humidity on Wildfire Smoke in Indoor Environments
LIORA MAEL, Andrew Martin, Kathryn Mayer, Dustin Poppendieck, Delphine K. Farmer, Marina Vance,
University of Colorado Boulder Abstract Number: 345
Working Group: Biomass Combustion: Outdoor/Indoor Transport and Indoor Air Quality
AbstractWildfires have been shown to have a significant impact on air quality in the United States and subsequently human health. An important, often overlooked, aspect of wildfire smoke studies is the potential transformations that smoke can undergo after it infiltrates into residential buildings and how this can influence the composition of the air indoors. During the Chemical Assessment of Surfaces and Air (CASA) study, fresh and aged smoke were injected into the NIST Net-Zero Energy Residential Test Facility, where the resulting differences in physical properties of the smoke, specifically sub- and supermicron particle diameter and number distributions were monitored using multiple Scanning Mobility Particle Sizers (SMPS) and an Aerodynamic Particle Sizer (APS). Ponderosa pine smoke was generated with a cocktail smoker to simulate wildfire smoke, and either directly injected into the house or aged in a flexible Teflon chamber with approximately 20 ppm (40 mg/m
3) of ozone for an hour prior to injection. To simulate circumstances when other sources of indoor air pollution are present, ozone was injected into the house following smoke additions, reaching concentrations of approximately 50 ppb (100 µg/m
3). When fresh smoke was directly injected into the house, no new particle formation (NPF) was observed following the ozone addition, however, NPF was observed with the addition of aged smoke and ozone, forming particles that remained <100 nm in diameter. Additionally, effects of high and low indoor relative humidity on particle size distributions were observed. These results will help us determine appropriate mitigation strategies and understand the health risks and impacts of wildfire smoke infiltration into houses.