Evaluation of Second-hand Exposure to Electronic Cigarette Vaping under a Real Scenario: Measurements of Ultrafine Particle Number Concentration and Size Distribution and Comparison with Traditional Tobacco Smoke.

Introduction:
This article evaluates the impact of e-cigarette second-hand aerosol on indoor air quality and potential passive exposure of bystanders. The study compares e-cigarette aerosol with tobacco smoke in terms of ultrafine particles (UFPs) number concentration and size distribution. The experimental design involved two volunteers vaping 15 different e-liquids inside a 49 m3room under natural ventilation conditions. high temporal resolution measurements were performed to simulate a realistic exposure scenario.

Key Points:

* The study found that e-cigarette second-hand aerosol increased UFPs number concentration, although it was up to two orders of magnitude lower than tobacco smoke.
* E-cigarette second-hand aerosol size distribution exhibited a bimodal behavior with modes at 10.8 and 29.4 nm, while tobacco smoke showed a unimodal distribution with a peak mode at 100 nm.
* In the size range 6-26 nm, particles concentration in e-cigarette second-hand aerosol was higher than in tobacco smoke, indicating that exhaled particles are nano-sized with high penetration capacity into human airways.
* The experimental design involved two volunteers vaping 15 different e-liquids inside a 49 m3room under natural ventilation conditions.
* high temporal resolution measurements were performed to simulate a realistic exposure scenario.
* E-cigarette second-hand aerosol increased UFPs number concentration, although it was up to two orders of magnitude lower than tobacco smoke.
* E-cigarette second-hand aerosol size distribution exhibited a bimodal behavior with modes at 10.8 and 29.4 nm, while tobacco smoke showed a unimodal distribution with a peak mode at 100 nm.
* In the size range 6-26 nm, particles concentration in e-cigarette second-hand aerosol was higher than in tobacco smoke, indicating that exhaled particles are nano-sized with high penetration capacity into human airways.

Main Message:
The main message of the article is that e-cigarette second-hand aerosol can increase UFPs number concentration, although it is up to two orders of magnitude lower than tobacco smoke. however, the size distribution of e-cigarette second-hand aerosol exhibits a bimodal behavior, with particles in the nano-size range, indicating that exhaled particles have high penetration capacity into human airways. This highlights the need for further research on the potential health impacts of e-cigarette second-hand aerosol and the need for appropriate regulations to protect bystanders from potential harm.

Palmisani J, Di Gilio a, Palmieri L, et al. Evaluation of Second-hand Exposure to Electronic Cigarette Vaping under a Real Scenario: Measurements of Ultrafine Particle Number Concentration and Size Distribution and Comparison with Traditional Tobacco Smoke. Toxics. 2019;7(4). doi:10.3390/toxics7040059