Automotive polycyclic aromatic hydrocarbons (PAH)
The International Agency for Research on Cancer has classified certain PAH as carcinogenic to animalsand probably carcinogenic to humans. Evidence for the carcinogenicity of some PAH is equivocal;for others there is no evidence of carcinogenic potential, and there are many others that havenot even been tested. There is no common definition for the term ‘polycyclic aromatic hydrocarbon’.While in some scientific disciplines PAH are understood to be individual polycyclic aromatichydrocarbons, in other areas the same term is used to define the total of all di- and tri+aromatic components determined in diesel fuel. Even in this area there is still some conflict, forexample, the Swedish diesel fuel specification uses the term PAH to refer only to tri+ aromatics. Due to the concern about potential health effects the European Commission will propose an AirQuality Standard for PAH under a Daughter Directive under the EU Air Quality Assessment andManagement Directive. The last CONCAWE Review outlined the complexity of the DaughterDirective for suspended particulate matter (PM10). The issue for PAH is also very complex withcontributions to ambient PAH coming from a range of different emission sources. This againnecessitates experts from various scientific disciplines and industries working together. In thiscontext it is worth noting that recent studies in various locations have demonstrated that the levelsof PAH in current ambient air are the lowest ever measured largely as a result of the reduceduse of coal in domestic and other heating.