Exploration of volatile organic compounds and combustion generated pollutants produced by structural fuels during wildfires

Abstract

Emissions from structural fires in the Wildland-Urban-Interface (WUI) such as carbon dioxide, carbon monoxide, particulate matter, soot and volatile organic compounds (VOCs) remain poorly characterized despite growing concern about their contribution to air pollution. To address this gap emissions were quantified during structural fire experiments conducted as part of the Burning Homes and Structural MAterials (BHASMA) project. More than 70 small-scale experiments were carried out at Colorado State University (CSU) in the summer of 2023 across 19 structural fuels and fuel mixtures representing common building materials. In addition, over 20 large-scale burns were performed at the National Institute of Standards and Technology (NIST) in 2024 using standardized fuel cribs composed of wood, gypsum board, and plastic components. Emissions were analyzed across both pyrolysis and flaming phases, resulting in the identification of over 70 unique VOC species. Synthetic materials—including insulation, flooring, and sheathing—produced elevated levels of hazardous air pollutants such as benzene and styrene, which were largely absent in lumber-only combustion. Emission profiles varied with combustion phase and fuel composition but showed general consistency across fire scales. Increased emissions from crib experiments, with respect to pure wood experiments, were associated with the addition of synthetic materials in the crib's composition. These results indicate that structural materials contribute to a distinct and toxic suite of VOCs, with important implications for human exposure, air quality modeling, and risk assessment in fire-prone WUI communities. Potential toxicological exposure and risk are evaluated using VOC emissions in a Gaussian plume model.