Indoor air pollution from e-cigs can be as bad as secondhand tobacco smoke in a smoky bar

Eric Soule and colleagues recently published an important paper documenting that people around e-cigarettes can be exposed to levels of particulate air pollution as high as has been measured in smoky bars.  Their paper “Electronic cigarette use and indoor air quality in a natural setting” published in Tobacco Control reporting the results of measuring the levels of air pollution at an “e-cigarette event” in a hotel meeting room where they measured the levels of fine particle air pollution during the event.
 
Specifically, they found very high levels of particles, varying between 300 and 820 µg/m3 .  These are levels that are found in very smoky bars or major forest fires.  (The levels were less than 4 µg/m3 before the event.
 
These measurements probably underestimate actual levels of pollution because the Sidepak device that was used to collect the data does not detect particles below 1 micron, which includes many e-cigarette aerosol particles.
 
Here is the abstract:
 
NTRODUCTION:
Secondhand smoke (SHS) from combustible cigarettes causes numerous diseases. Policies have been developed to prevent SHS exposure from indoor cigarette use to reduce health risks to non-smokers. However, fewer policies have been implemented to deter electronic cigarette (ECIG) use indoors, and limited research has examined the impact of secondhand exposure to ECIG aerosol.
METHODS:
Indoor air quality was measured at a 2-day ECIG event held in a large room at a hotel. Fine particulate matter (PM) was measured using 2 devices that measured concentrations of PM 2.5 μm aerodynamic diameter or smaller (PM2.5). Measurements were taken before the event, over 2 days when the event was ongoing, and the day after the event. PM2.5 measurements were also taken from the restaurant at the hotel hosting the event and a restaurant at a nearby hotel.
RESULTS:
During 6 time points when the event was ongoing, between 59 and 86 active ECIG users were present in the event room (room volume=4023 m3). While the event was ongoing, median PM2.5 concentrations in the event room increased from a baseline of 1.92-3.20 μg/m3 to concentrations that ranged from 311.68 μg/m3 (IQR 253.44-411.84 μg/m3) to 818.88 μg/m3 (IQR 760.64-975.04 μg/m3).
CONCLUSIONS:
PM2.5 concentrations observed at the ECIG event were higher than concentrations reported previously in hookah cafés and bars that allow cigarette smoking. This study indicates that indoor ECIG use exposes non-users to secondhand ECIG aerosol. Regulatory bodies should consider establishing policies that prohibit ECIG use anywhere combustible cigarette use is prohibited.
 
The full citation is Soule E, et al.  Electronic cigarette use and indoor air quality in a natural setting.  Tob Control. 2017 Jan;26(1):109-112. doi: 10.1136/tobaccocontrol-2015-052772. Epub 2016 Feb 15.  It is available here.