Numerical investigations on the contribution of point source emissions to the PM2.5 concentrations in Fairbanks, Alaska

Simulations with and without consideration of emissions from point sources were performed with the Weather Research and Forecasting model with online chemistry (WRF/Chem) to examine the contribution of point source emissions to the PM2.5 concentrations at breathing level in Fairbanks, Alaska during winter. On days and at locations where PM2.5 concentrations exceed the National Ambient Air Quality Standard of 35 μg m −3, emissions from point sources account for 4% of the 24 h–average PM2.5 concentration on average. The locations of highest concentrations were the same in both simulations. Point source emissions induced only five additional exceedance days in the nonattainment area. The magnitude of the PM2.5 concentrations depended on meteorological conditions (temperature, wind speed, mixing height) and emissions. The radius of impact of point source emissions on the PM2.5 concentration at breathing level of about 10–12 km downwind results as a combination of low emission heights, low wind speeds and the presence of inversions.