Particulate matter from tobacco versus diesel car exhaust: an educational perspective

Background: Air pollution is a common alibi used by adolescents taking up smoking and by smokers uncertain about quitting. However, environmental tobacco smoke (ETS) causes fine particulate matter ( PM) indoor pollution exceeding outdoor limits, while new engines and fuels have reduced particulate emissions by cars. Data comparing PM emission from ETS and a recently released diesel car are presented. Methods: A 60 m(3) garage was chosen to assess PM emission from three smouldering cigarettes ( lit sequentially for 30 minutes) and from a TDCi 2000cc, idling for 30 minutes. Results: Particulate was measured with a portable analyser with readings every two minutes. Background PM10, PM2.5, and PM1 levels (mean (SD)) were 15 (1), 13 (0.7), and 7 (0.6) mug/m(3) in the car experiment and 36 (2), 28 (1), and 14 (0.8) mug/m(3) in the ETS experiment, respectively. Mean (SD) PM recorded in the first hour after starting the engine were 44 ( 9), 31 ( 5), and 13 ( 1) mug/m(3), while mean PM in the first hour after lighting cigarettes were 343 ( 192), 319 (178), and 168 (92) mug/m(3) for PM10, PM2.5, and PM1, respectively ( p< 0.001, background corrected). Conclusions: ETS is a major source of PM pollution, contributing to indoor PM concentrations up to 10-fold those emitted from an idling ecodiesel engine. Besides its educational usefulness, this knowledge should also be considered from an ecological perspective.