Investigations on the impact of single direct and indirect, and multiple emission–control measures on cold–season near–surface PM2.5 concentrations in Fairbanks, Alaska

The impact of two direct (wood–burning device changeout, introduction of gas), an indirect (introduction of low–sulfur fuel) and a multiple (wood–burning device changeout plus introduction of low–sulfur fuel) emission control measure on near surface PM2.5 concentrations in Fairbanks, Alaska was examined for a cold season by WRF/Chem simulations and the 2008/09 hourly observations. The benefits for air quality would vary in persistence and the diurnal course among measures. None of these emission control measures would provide design values below the National Ambient Air Quality Standard (35 µg m–3). Substituting all wood–burning by gas would reduce PM2.5 emissions by ~11% and the 2008 design value of 44.7 µg m–3 to 38.9 µg m–3. The estimated ~4% PM2.5 emission decrease due to changeout of noncertified by certified wood–burning devices would reduce the design value to 42.3 µg m–3. The use of low–sulfur fuel in oil–fired furnaces and facilities would reduce total SO2 and PM2.5 emissions by ~23 and 15%, respectively, but provide a similar design value. The multiple emission control measure would reduce these emissions by ~36 and 19%, respectively, and the design value to 39.3 µg m–3. The indirect emission control measure is most sensitive to meteorology. The efficiency of the multiple emission control measures is not generally the sum of the efficiency of the respective single measures.