TAPaC-tobacco-associated particulate matter emissions inside a car cabin: establishment of a new measuring platform.

Background: Particulate matter (PM) emission caused by tobacco combustion leads to severe health burdens worldwide. Second-hand smoke exposure is extraordinarily high in enclosed spaces (e.g., indoor rooms, car cabins) and poses a particular threat to the health of vulnerable individuals (e.g., children, elderly, etc.). This study aimed to establish a new measuring platform and investigate PM emissions under four different ventilation conditions inside a car cabin without exposing any person to harmful tobacco smoke.

Methods: PM concentrations were measured during the smoking of 3R4F reference cigarettes in a Mitsubishi Space Runner (interior volume 3.709 m). The cigarettes were smoked with a machine, eliminating exposure of the researchers. Cigarettes were extinguished 4.5 min after ignition, and PM measurements continued until 10 min after ignition.

Results: High mean PM concentrations were measured for cigarettes without ventilation after 4.5 min (PM: 1150 µg/m, PM: 1132 µg/m, PM: 861.6 µg/m) and after 10 min (PM: 1608 µg/m, PM: 1583 µg/m, PM: 1133 µg/m). 3R4F smoked under conditions with turned on ventilation resulted in reduction of PM compared to those smoked without ventilation after 4.5 min (PM:-47.5 to -58.4%, PM:-47.2 to -58%, PM:-39.6 to -50.2%) and after 10 min (PM:-70.8 to -74.4%, PM:-70.6 to -74.3%, PM:-64.0 to -68.0%). Cigarettes smoked without ventilation generated high PM peaks at 4.5 min (PM: 2207 µg/m, PM: 2166 µg/m, PM: 1421 µg/m) and at 10 min (PM: 1989 µg/m, PM: 1959 µg/m, PM: 1375 µg/m). PM peaks of cigarettes smoked under different ventilation modes varied at 4.5 min (PM: 630-845 µg/m, PM: 625-836 µg/m, PM: 543 - 693 µg/m) and 10 min (PM: 124 - 130 µg/m, PM: 124 - 129 µg/m, PM: 118 - 124 µg/m).

Conclusion: The new measuring platform provides a safer way for researchers to investigate PM emissions of cigarettes. These data are comparable to published research and show that smoking in a parked vehicle with the windows closed generates harmful PM emissions even when the vehicle ventilation is in operation. Future studies should be carried out using the new measuring platform investigating PM exposure and PM distribution of in-vehicle smoking under a wide range of conditions.