Second-hand aerosol from tobacco and electronic cigarettes: Evaluation of the smoker emission rates and doses and lung cancer risk of passive smokers and vapers

Introduction:
This text provides an in-depth analysis of the aerosol emissions of smokers and vapers in a naturally-ventilated 40-m3 test room. It calculates the particle dose deposited in the respiratory tree of passively exposed individuals using the MPPD model and estimates the lung cancer risks of second-hand smokers. The text also discusses the emission rates, particle number concentrations, size distributions, PM10, and Black Carbon.

Key Points:

* The median emission rates of smokers and vapers in terms of particle number are 4.3 x 1011 part·min -1 (2.80 x 1012 part·cig-1) and 9.62 x 1010 part· min-1 (5.51 x 1011 part·cig-1), respectively.
* Significant PM10 (4.92 mg min-1; 32.0 mg cig-1) and BC (66.2 !Jg min-1; 430 f..lg cig-1) emissions were estimated for tobacco cigarette smokers, whereas the relevant vaper emissions were negligible.
* after 1 h exposure time, the extra doses received by second-hand smokers and vapers in terms of particle number/surface area in the lung (sum of alveolar and tracheobronchial regions) for the exposure scenario considered are equal to 1 x 1010 particles/485 mm2 and 1 x 109 particles/ 3.6 mm2.
* Depending on the airway generation, up to 15-fold higher cumulative doses were estimated for passively exposed smokers than for passively exposed vapers.
* The lung cancer risk for second-hand smokers is five orders of magnitude larger than for second-hand vapers.
* The study used the most suitable model currently available to compare different exposure scenarios and provide good estimates of the relative differences among them.
* The model is not able to take into account non-linear effects of age, previous smoking/vaping history, possible synergic effects due to exposures to other chemicals, effect of pre-existing pathologies, or the particle assumption rate.

Main Message:
The study finds that the lung cancer risk for second-hand smokers is five orders of magnitude larger than for second-hand vapers. The MPPD model is used to estimate the dose and lung cancer risk received by passive smokers and vapers for a certain exposure scenario. The study's findings are important for regulatory matters as they provide critical information about the health risks associated with passive smoking and vaping. The study's limitations, such as the model's inability to account for non-linear effects, should be considered when interpreting the results.

avino, Pasquale, Mauro Scungio, Luca Stabile, Gino Cortellessa, Giorgio Buonanno, and Maurizio Manigrasso. “Second-hand aerosol from Tobacco and Electronic Cigarettes: Evaluation of the Smoker Emission Rates and Doses and Lung Cancer Risk of Passive Smokers and Vapers.” Science of The Total Environment 642 (November 2018): 137–47. https://doi.org/10.1016/j.scitotenv.2018.06.059.