Polycyclic Aromatic Hydrocarbons (PAHs) Quantified in Large-Scale Fire Experiments

A number of large-scale fire experiments with detailed quantitative analysis of polycyclic aromatic hydrocarbon (PAH) including PAH congener distribution have been conducted by SP. This data is reviewed here and is further assessed with regard to toxicity applying a Toxic Equivalency Factor (TEF) model for estimation of cancer potential. The PAH yield data from the large-scale fire experiments is also compared to emission factors from other combustion sources. The study shows that full-scale fire experiments with different products exhibit a large variation in total PAH yields. Fires with products containing flame retardants were shown to produce the highest yields and generally a more toxic mixture of PAHs than fires with non-flame retarded products. The distribution of individual PAH congeners is generally quantitatively dominated by low molecular weight PAHs, whereas a small number of medium to high molecular weight PAHs are most important in determining the toxicity of the PAH mixture. The large-scale fire experiments indicate that fires normally produce orders of magnitudes higher yields compared to, e. g. modern residential combustion devices. The relative distribution of individual PAHs, which determines the toxicity of the PAH mix, is similar for the fires and open burning data studied, in that benzo(a)pyrene and dibenz(a,h)anthracene dominate the toxicity of the mix as a whole.