Waterpipe-associated particulate matter emissions

Waterpipe tobacco smoking is increasingly common worldwide, and evidence about its harmful effects to smokers is emerging. However, no studies have investigated the potential exposure of nonsmokers to waterpipe smoke. We measured particulate matter (PM) emissions (PM2.5, PM10) before and during laboratory sessions in which 20 individuals used a waterpipe to smoke tobacco and 20 individuals smoked a cigarette (10 for each particle-size/smoking-method), as well as 10 waterpipe and 10 cigarette smoldering sessions (i.e., without a smoker). A TSI-SidePak aerosol monitor obtained PM2.5, PM10 background, smoking, and maximum levels. Mean PM2.5 rose 447% for waterpipe (from 48 mu g/m(3) background to 264 mu g/m(3) smoking), and by 501% for cigarettes (from 44 mu g/m(3) to 267 mu g/m(3)), whereas mean PM10 rose by 563% for waterpipe (from 55 mu g/m(3) to 365 mu g/m3), and by 447% for cigarettes (from 52 mu g/m(3) to 287 mu g/m(3)) (p<.05 for all). The increase in PM during cigarette smoking was due primarily to PM2.5, given that the proportion of PM2.5 from total PM10 increase was 95% compared with 70% for waterpipe (p<.05). Maximum PM2.5 was 908 mu g/m(3) for waterpipe and 575 mu g/m(3) for cigarettes, whereas maximum PM10 was 1052 mu g/m(3) for waterpipe and 653 mu g/m(3) for cigarettes. Mean PM2.5 and PM10 smoldering levels did not differ from background for waterpipe but were significantly higher for cigarettes (PM2.5: 33-190 mu g/m(3); PM10: 42-220 mu g/m(3)). Policymakers considering clean air regulations should include waterpipe tobacco smoking, and the public should be warned about this source of smoke exposure.