Assessing Impacts of the Severe Air Pollution Caused by the Camp Fire (2018)

To date, the Camp Fire of November 2018 was the deadliest and most destructive wildfire in California. Originating along the Sierra Nevada, smoke from the fire spread across the Central Valley to the San Francisco Bay Area. Levels of particulate matter less than 2.5 µm in diameter (PM_2.5) in the San Francisco area peaked at values greater than 200 µg m^-3 and remained above 50 µg m^-3, more than four times the annual mean PM_2.5 U.S. National Ambient Air Quality Standard, for nearly two weeks. It is increasingly important to understand wildfires as the number of extreme events and length of the wildfire season continue to grow. To study the impact of the Camp Fire on regional air quality, we analyze station observations of PM_2.5 across northern California, simulate the Camp Fire using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), and evaluate the models’ performance against ground and space measurements (surface PM_2.5, BC; TROPOMI CO, NO₂, aerosol index; MODIS AOD). We conduct WRF-Chem sensitivity simulations to understand uncertainties that arise from fire emissions, meteorological conditions, representation of aerosol processes, the feedback of aerosol radiative effects on meteorology, and various physical parameterizations. We also estimate health exposure and economic impact by linking the WRF-Chem output with an integrated assessment model. Results of this study can assist in the production of data assimilation systems and air quality forecasting.