Fig. 7.
Comparison of mutagenicity EFs of the burn pit smoke and various combustion smoke PMs in strain TA98 + S9. Mutagenicity emission factor (EF) calculated based on the emitted PM mass per mass of fuel burned. Mutagenic potencies of the PM (rev/µg PM; Fig. 6a) were converted to mutagenicity EFs (rev/MJth) using the values for the heat energy of each fuel (MJth/kg fuel). Data are presented as mean ± SEM. #Mutagenicity EFs were estimated based on the assumption that 80% of the emissions were produced by flaming and 20% by smoldering. $Mutagenicity EFs were estimated based on the assumption that 20% of the emissions were produced by flaming and 80% by smoldering. The mutagenicity EFs for biomass smoke were 1.2, 5.8, 3.3, 2.5, and 1.9 × 105 rev/MJth for the red oak, peat, pine needles, pine and eucalyptus, respectively [49]. The mutagenicity EFs for diesel smoke were 0.4, 0.2, and 0.1 × 105 rev/MJth for the diesel exhaust particles, B20 exhaust particles, and B100 exhaust particles, respectively [46]. The mutagenicity EFs for cookstove smoke were 2.4, 1.2, and 0.2 × 105 rev/MJth for the three-stone fire, natural-draft stove, and force-draft stove, respectively [45]. The mutagenicity EFs for waste smoke were 0.4, 1.9, and 22.7 × 105 rev/MJth for the municipal waste [82], oil [102], and tire [79], respectively