Characterizing Emissions from Prescribed Fires and Assessing Impacts to Air Quality in the Lake Tahoe Basin Using Disperison Modeling

Abstract

A PM2.5 monitoring network was established around Lake Tahoe during fall 2011, which, in conjunction with measurements at prescribed burns and smoke dispersion modeling based on the Fire Emission Production Simulator and the Hybrid Single Particle Lagrangian Integrated Trajectory (FEPS-HYSPLIT) Model, served to evaluate the prescribed burning impacts on air quality. Emissions from pile and understory prescribed burns were characterized using a mobile air monitoring system. In field PM2.5 emission factors showed ranges consistent with laboratory combustion of wet and dry fuels. Measurements in the smoke plume showed progression from flaming to smoldering phase consistent with FEPS and PM2.5 emission factors generally increased with decreasing combustion efficiency. Model predicted smoke contributions are consistent with elevated ambient PM2.5 concentrations in three case studies, and high meteorological model resolution (2km x 2 km) seems to produce accurate smoke arriving times. In other cases, the model performance is difficult to evaluate due to low predicted smoke contributions relative to the typical ambient PM2.5 level. Synergistic assessment of modeling and measurement can be used to determine basin air quality impact. The findings from this study will help land management agencies better understand the implications of managing fire at the wildland-urban interface.