Secondhand electronic cigarette aerosol in vehicles impacts indoor air quality.

Background: Electronic cigarette (ECIG) use in vehicles represents a public health concern due to the potential for exposure to high concentrations of particulate matter (PM) and other toxicants. This study examined the impact of ECIG use on air quality in vehicles.

Methods: People who reported current ECIG use (n=60; mean age=20.5, SD=2.3) completed a brief survey and a 30-min ECIG use session in their own vehicle. Using a protocol similar to clinical laboratory studies involving tobacco use, participants took 10 directed puffs (i.e., a directed bout with one puff every 30s for 5min) followed by a 25-min ad libitum period in which participants took as many puffs as desired. PM 2.5µm in diameter or smaller (PM) were measured using aerosol monitors set up to sample air from the breathing zone of the passenger seat and total puffs were recorded. The association between peak PM concentration and puff count was examined.

Results: Participants took a median 18 total puffs during the sessions. Median PM concentrations increased from 4.78µg/m at baseline to 107.40µg/m after the directed bout. Median peak PM concentration was 464.48µg/m and ranged from 9.56µg/m to 143,503.91µg/m (IQR=132.72-1604.68). After removing two extreme outliers for puff count and PM concentrations, puff count was significantly correlated with peak PM concentration during the ad libitum bout (r=0.32, p=0.015).

Conclusions: ECIG use in vehicles impacts air quality negatively and may pose health risks to those present in vehicles when ECIG use is occurring.