Particulate matter (PM) 2.5 levels in ETS emissions of a Marlboro Red cigarette in comparison to the 3R4F reference cigarette under open- and closed-door condition.

Introduction: Potential health damage by environmental emission of tobacco smoke (environmental tobacco smoke, ETS) has been demonstrated convincingly in numerous studies. People, especially children, are still exposed to ETS in the small space of private cars. Although major amounts of toxic compounds from ETS are likely transported into the distal lung via particulate matter (PM), few studies have quantified the amount of PM in ETS.

Study Aim: The aim of this study was to determine the ETS-dependent concentration of PM from both a 3R4F reference cigarette (RC) as well as a Marlboro Red brand cigarette (MRC) in a small enclosed space under different conditions of ventilation to model car exposure.

Method: In order to create ETS reproducibly, an emitter (ETSE) was constructed and mounted on to an outdoor telephone booth with an inner volume of 1.75 m3. Cigarettes were smoked under open- and closed-door condition to imitate different ventilation scenarios. PM2.5 concentration was quantified by a laser aerosol spectrometer (Grimm; Model 1.109), and data were adjusted for baseline values. Simultaneously indoor and outdoor climate parameters were recorded. The time of smoking was divided into the ETS generation phase (subset "emission") and a declining phase of PM concentration (subset "elimination"); measurement was terminated after 10 min. For all three time periods the average concentration of PM2.5 (Cmean-PM2.5) and the area under the PM2.5 concentration curve (AUC-PM2.5) was calculated. The maximum concentration (Cmax-PM2.5) was taken from the total interval.

Results: For both cigarette types open-door ventilation reduced the AUC-PM2.5 (RC: from 59 400 ± 14 600 to 5 550 ± 3 900 μg*sec/m3; MRC: from 86 500 ± 32 000 to 7 300 ± 2 400 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 600 ± 150 to 56 ± 40 μg/m3, MRC from 870 ± 320 to 75 ± 25 μg/m3; p < 0.001) by about 90%. Cmax-PM2.5 was reduced by about 80% (RC: from 1 050 ± 230 to 185 ± 125 μg/m3; MRC: from 1 560 ±500 μg/m3 to 250 ± 85 μg/m3; p < 0.001). In the subset "emission" we identified a 78% decrease in AUC-PM2.5 (RC: from 18 600 ± 4 600 to 4 000 ± 2 600 μg*sec/m3; MRC: from 26 600 ± 7 200 to 5 800 ± 1 700 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 430 ± 108 to 93 ± 60 μg/m3; MRC: from 620 ± 170 to 134 ± 40 μg/m3; p < 0.001). In the subset "elimination" we found a reduction of about 96-98% for AUC-PM2.5 (RC: from 40 800 ± 11 100 to 1 500 ± 1 700 μg*sec/m3; MRC: from 58 500 ± 25 200 to 1 400 ± 800 μg*sec/m3; p < 0.001) and Cmean-PM2.5 (RC: from 730 ± 200 to 27 ± 29 μg/m3; MRC: from 1 000 ± 450 to 26 ± 15 μg/m3; p < 0.001). Throughout the total interval Cmax-PM2.5 of MRC was about 50% higher (1 550 ± 500 μg/m3) compared to RC (1 050 ± 230 μg/m3; p < 0.05). For the subset "emission" - but not for the other periods - AUC-PM2.5 for MRC was 43% higher (MRC: 26 600 ± 7 200 μg*sec/m3; RC: 18 600 ± 4 600 μg*sec/m3; p < 0.05) and 44% higher for Cmean-PM2.5 (MRC: 620 ± 170 μg/m3; RC: 430 ± 108 μg/m3; p < 0.05).

Conclusion: This method allows reliable quantification of PM2.5-ETS exposure under various conditions, and may be useful for ETS risk assessment in realistic exposure situations. The findings demonstrate that open-door condition does not completely remove ETS from a defined indoor space of 1.75 m3. Because there is no safe level of ETS exposure ventilation is not adequate enough to prevent ETS exposure in confined spaces, e.g. private cars. Additionally, differences in the characteristics of cigarettes affect the amount of ETS particle emission and need to be clarified by ongoing investigations.