Laboratory Analysis of VOC Emissions from Structural Materials in Wildland–Urban Interface Fires

The wildland–urban interface (WUI) has grown in
recent decades
at the same time as wildfires have expanded in range and scope. Fires
at the WUI are therefore more common, and structural materials make
up more of the wildfire fuel mass. While emissions from biomass fires
are fairly well understood, volatile organic compound (VOC) emissions
from structural fires are less constrained. In this study, we perform
measurements of VOC emissions from small-scale laboratory burns of
18 different structural materials across 78 experiments using a Vocus
proton-transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS)
to better understand these unique emissions. We calculate emission
factors for 73 VOCs across all materials, including aromatics and
polycyclic aromatic hydrocarbons (PAHs). We compare the emissions
from both flaming and pyrolysis, which separate the processes of direct
release of VOCs from combustion formation. Mass spectra comparisons
were used to qualitatively highlight high-emission compounds across
materials and identify notable emissions (e.g., nylon monomers) and
potential tracers (e.g., halogen species) for WUI fires. Using these
data, the emissions from a whole-house fire were compared with those
from an equivalent mass of wood, and we found that some aromatic and
nitrile species may be suitable WUI fire tracers.