Indoor air contamination during a waterpipe (narghile) smoking session

The smoke of waterpipe contains numerous substances of health concern, but people mistakenly believe that this smoking method is less harmful and addictive than cigarettes. An experiment was performed in a 57 m 3 room on two dates with no smoking on the first date and waterpipe smoking for 4 h on the second date. We measured volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), metals, carbon monoxide (CO), nitrogen oxides (e.g. NO), as well as particle mass (PM), particle number concentration (PNC) and particle surface area in indoor air. High concentrations were observed for the target analytes during the 4-h smoking event. The median (90th percentile) values of PM 2.5, PNC, CO and NO were 393 (737 μg/m 3), 289,000 (550,000 particles/cm 3), 51 (65 ppm) and 0.11 (0.13 ppm), respectively. The particle size distribution has a maximum of particles relating to a diameter of 17 nm. The seven carcinogenic PAH were found to be a factor 2.6 higher during the smoking session compared to the control day. In conclusion, the observed indoor air contamination of different harmful substances during a WP session is high, and exposure may pose a health risk for smokers but in particular for non-smokers who are exposed to ETS.