Polycyclic Aromatic Compounds in the Atmosphere – A Review Identifying Research Needs

Most of the 16 EPA priority PAHs (or a subset of these) are targeted in the current monitoring of air and air pollution studies. However, other parent PAHs may account for up to another ≈10%, nitro-PAHs up to ≈20%, and oxy-PAHs for even more. The reactivity in the atmospheric gas and particulate phases is incompletely quantified, in particular with regard to coverage of aerosol matrix diversity and photochemical age. Therefore, the model-based characterization of exposure is still limited. Nitro- and oxy-PAHs pose a higher health risk in ambient air than parent PAHs but have not been measured as extensively so far and are usually not included in monitoring programs. Nitro-PAHs are also interesting as tracers for air pollution source identification and pathways of photochemistry. Among heterocyclic aromatic compounds in ambient air dibenzofuran and dibenzothiophene should be targeted.