Impacts of Aging and Relative Humidity on Physical Properties of Wildfire Smoke
Liora Mael, SOFIE SCHWINK, Thomas Dunnington, Nicholas Gotlib, Marina Vance,
University of Colorado Boulder Abstract Number: 275
Working Group: Aerosol Chemistry
AbstractSmoke inhalation can cause short- and long-term health effects, including respiratory irritation, shortness of breath, exacerbation of asthma, and chronic heart disease. The occurrence of wildfire events is increasing across the United States, making it vital that we understand how wildfire smoke impacts human health and how its properties evolve in indoor environments. Building on work done during the 2022 Chemical Assessment of Surfaces and Air (CASA) indoor chemistry field campaign, we performed controlled laboratory experiments measuring physical properties of smoke aerosols, including size distributions, aerosol liquid water content (ALWC), and aerosol effective density (ρ
eff). Size distributions were measured using a pair of scanning mobility particle sizers (SMPS), with and without a diffusion dryer. Particle mass was determined using an aerosol particle mass spectrometer (APM). Data from these instruments were combined to determine ALWC and ρ
eff. Fresh and aged (via ozone oxidation) experiments were conducted in a 0.68 m
3 stainless steel chamber with three relative humidity levels: low, medium, and high. These different environmental conditions led to changes in particle size distribution, effective density, and water uptake. Differences in these properties over time and in different ambient conditions could lead to changes in health effects of exposure to smoke as well as calibration factors for low-cost sensor applications, so it is important to understand and quantify physical changes of smoke over a range of conditions.