PM Origin or Exposure Duration? Health Hazards from PM-Bound Mercury and PM-Bound PAHs among Students and Lecturers

This study assessed inhalation exposure to particulate matter (PM₁)-bound mercury (Hg_p) and PM₁-bound polycyclic aromatic hydrocarbons (PAHs) among university students. For this purpose, simultaneous indoor (I) and outdoor (O) measurements were taken from two Polish technical universities (in Gliwice and Warsaw) located in distinct areas with respect to ambient concentrations and major sources of PM. The indoor geometric mean concentrations of Hg_p were found to be 1.46 pg·m^-3 and 6.38 pg·m^-3 in Warsaw and Gliwice, while the corresponding outdoor concentrations were slightly lower at 1.38 pg·m^-3 and 3.03 pg·m^-3, respectively. A distinct pattern was found with respect to PAH concentrations with estimated I/O values of 22.2 ng·m^-3/22.5 ng·m^-3 in Gliwice and 10.9 ng·m^-3/11.12 ng·m^-3 in Warsaw. Hazard quotients (HQs) as a result of exposure to Hg_p for students aged 21 ranged from 3.47 × 10^-5 (Warsaw) to 1.3 × 10^-4 (Gliwice) in terms of reasonable maximum exposure (RME). The non-cancer human health risk value related to Hg_p exposure was thus found to be below the acceptable risk level value of 1.0 given by the US EPA. Daily exposure values for lecture hall occupants, adjusted to the benzo(a)pyrene (BaP) toxicity equivalent (BaP_eq), were 2.9 and 1.02 ng·m^-3 for the Gliwice and Warsaw students, respectively. The incremental lifetime cancer risk (ILCR) values with respect to exposure to PM₁-bound PAHs during the students' time of study were 5.49 × 10^-8 (Warsaw) and 1.43 × 10^-7 (Gliwice). Thus, students' exposure to indoor PAHs does not lead to increased risk of lung cancer.