Polycyclic aromatic hydrocarbons including dibenzopyrenes in indoor air samples from schools and residences in Germany

Polycyclic aromatic hydrocarbons (PAH) are several hundred organic substances that are formed in the course of incomplete combustion of organic material. Of particular importance are the carcinogenic effects of PAH. Various dibenzopyrenes as well as benzo[c]fluorene (BcFl) seems to have a particular toxicological potency, which have hardly been investigated in indoor air so far.Therefore, the indoor air samples of 27 classrooms and 35 central living spaces of residences in Germany were collected to analyze 56 particle-bound PAH as well as naphthalene (Nap).The PM10 values in schools and residences ranged between 9.1 and 210 & mu;g/m3 (mean: 93.4 & mu;g/m3) and from 3.6 to 52.0 & mu;g/m3 (mean: 12.0 & mu;g/m3), respectively. For the sum of the 16 priority US EPA PAH (except acenaphthylene and naphthalene) means (95th percentiles) in classrooms and residences were 1.20 ng/m3 (2.77 ng/m3) and 0.84 ng/m3 (2.64 ng/m3), respectively. Higher values were observed for naphthalene with mean concentrations of 596 ng/m3 (2,800 ng/m3) in classrooms and 243 ng/m3 (530 ng/m3) in residences.For classrooms and residences mean concentrations of 8.3 pg/m3 and 7.4 pg/m3 for dibenzo[a,l]pyrene (DBalPyr), 16.4 pg/m3 and 11.9 pg/m3 for dibenzo[a,e] pyrene (DBaePyr), 9.2 and 5.7 pg/m3 for dibenzo[a,h]pyrene (DBahPyr), and 6.4 and 4.2 pg/m3 for BcFl were observed, respectively, while DBaiPyr was found in only one sample above LOD.The BaPeq (benzo[a]pyrene equivalents) for the sum of 20 PAH is on average 482 pgTEQ/m3 (schools) and 393 pgTEQ/m3 (residences), which corresponds to an incremental lifetime cancer risk to 42 x 10-6 and 34 x 10-6.Although dibenzopyrenes and BcFl are found only in very low concentrations in indoor air, they have a significant impact on the risk if the assumptions about the toxicological potency of this group turn out to be valid.