PAHs in Smoke from Various WUI Fire Fuels: Cars, Trees, and Construction Materials

AIKA DAVIS, Thomas Cleary, Ryan Falkenstein-Smith, NIST

     Abstract Number: 205
     Working Group: Burning Questions of Aerosol Emissions, Chemistry, and Impacts from Wildland-Urban Interface (WUI) Fires

Abstract
WUI (Wildland-Urban Interface) fire smoke is complex since it contains anthropogenic and biogenic fuel sources, and emissions from WUI fire are not yet well characterized. We have conducted a comprehensive study to characterize polycyclic aromatic hydrocarbon (PAH) emission yields from select WUI fire fuels: internal combustion cars, 30 ft Douglas fir trees, and construction materials in a stacked array to mimic a structure. The mixed fuel cribs (1 ft to 2 ft on each side, constructed in a cube) consisted of sticks of wood, gypsum board, OSB, ABS, PU, and PVC. These WUI fire fuels were burned under oxygen consumption calorimeters to measure mass loss, heat release rate, and other combustion characteristic measurements throughout each test. The calorimeter’s exhaust hood captured the fire plume, and smoke samples were continuously collected from the exhaust duct at a well-mixed location for the test duration. Sampling pumps pulled smoke samples from the duct through a 47.0 mm quartz filter at 2.5 LPM to 4.0 LPM, a sorbent tube at 0.2 LPM to 0.4 LPM, and another bypass pump to adjust the flow to meet isokinetic sampling conditions. Thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) was used for gas and particulate phase PAH analysis. To determine the concentration of PAHs on soot particulates, a small section was cut out from the quartz filter and inserted into an empty stainless TD tube, directly desorbing with the TD unit at a slightly higher temperature than the PAH method for sorbent tubes. The talk will discuss the details of the experiments, burn behavior of the three fuel types, PAH emission yields, and the differences in yields among the fuel sources studied.