Exposure characterization
The particle exposure inside the exposure chamber was monitored and characterized during each exposure session from the first person entering the chamber until the last person leaving the chamber. Online monitoring of particle mass was performed by a Dusttrak Aerosol Monitor 8520 equipped with a PM2.5 inlet (TSI, St Paul, Minnesota) to control the exposure level. Particles (PMImages of SKC PTFE filters (PMThe Supplementary section thoroughly describes the analytical method and quality assurance results for the PAH analysis. In brief, before extraction of the PM