Citation:

Pye, H., L. Xu, B. Henderson, D. Pagonis, P. Campuzano-Jost, H. Guo, J. Jimenez, Christine Allen, N. Skipper, H. Halliday, Ben Murphy, E. D'Ambro, P. Wennberg, B. Place, F. Wiser, V. McNeill, E. Apel, D. Blake, M. Coggon, J. Crounse, J. Gilman, G. Gkatzelis, T. Hanisco, G. Huey, J. Katich, A. Lamplugh, J. Lindaas, J. Peischl, J. St. Clair, C. Warneke, G. Wolfe, AND C. Womack. Understanding the evolution of reactive organic carbon in wildfire plumes. 18th International Congress on Combustion By-products and their Health Effects, Durham, NC, May 20 - 22, 2024.

Impact/Purpose:

Wildfires emit organic compounds that include hazardous air pollutants. In addition, organic compounds make up the majority (>80%) of the fine particulate matter emitted by fires. In this work, we develop an estimate of reactive organic carbon (ROC) wildland fire emissions across the entire volatility spectrum and compare them to operational methods used by EPA. In addition, cancer and noncancer health impacts are estimated for the organic species in wildland fire smoke. This work highlights a need for cancer toxicity values for wildland fire particulate matter.

Description:

Wildfires are an increasingly prominent source of emissions to air including particulate matter and hazardous air pollutants. Understanding the health implications of wildfire smoke is complicated by the fact that the composition of smoke emissions as well as their transformation products are incompletely characterized. In this work, we aim to build a relatively complete description of reactive organic carbon (ROC) emissions and their secondary products in wildland fires using a combination of observations and model predictions. Specifically, we gather observations from the DC-8 aircraft for western U.S. wildfires during the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign and compare to predictions from the Community Multiscale Air Quality (CMAQ) model. Within CMAQ, we use the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) with AMORE isoprene chemistry which has expanded secondary organic aerosol precursors including phenols, cresols, furans, semivolatile organic compounds, and intermediate volatility organic compounds relevant for wildland fires. We find the base model captures 77 % by mole of measured gas-phase ROC emissions. However, underestimates in emissions result in organic aerosol being underestimated by a factor of 6 near the source. After updating the emission inputs and chemical evolution of wildfire smoke, species concentrations will be extended to cancer and non-cancer estimates of toxicity.

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