Optical Properties of Aerosols Generated from a Simulated Structural Burn

GEOFFREY SMITH, Ryan Poland, John Allen, Muhammad Abdurrahman, Michael Caraway, Thomas Carroll, Mike Lesiak, Mac A. Callaham, Joseph O'Brien, Andrew Metcalf, Pengfei Liu, Rawad Saleh, University of Georgia

     Abstract Number: 222
     Working Group: Burning Questions of Aerosol Emissions, Chemistry, and Impacts from Wildland-Urban Interface (WUI) Fires

Abstract
We present results from simulated structural burns conducted as part of the second Georgia WIldland fire Simulation Experiment (G-WISE 2) conducted in Athens, GA in April/May 2025. In these experiments, a fuel bed consisting of carpet, plastic, plywood and insulation was combusted, and optical properties of the emitted aerosols were measured using a home-built 4-wavelength photoacoustic spectrometer (MultiPAS-IV: 406/532/663/783 nm) along with a single-particle soot photometer (SP2). We measured absorption coefficients, mass absorption coefficients (MACs), absorption Angstrom exponents (AAEs) and single-scattering albedos (SSAs), for both thermodenuded (100 °C and 300 °C) and unthermodenuded particles allowing us to relate the optical properties to aerosol volatility fractions. Compared to aerosols from simulated wildland fires, we find that the aerosols emitted from structural burns contained much less volatile material and a much smaller contribution from brown carbon. Values of the optical properties generally resemble those of black carbon particles and do not change upon thermodenuding up to a temperature of 300 °C. However, we did find that the AAE values were consistently below 1, indicating that the particles may not consist exclusively of black carbon.