ASHRAE Journal - June 2014 - 38

Column Iaq applIcatIons

The Hazards of E-Cigarettes
By Francis (Bud) J. OFFermann, p.e., ciH, memBer asHrae

The prevalence of the use of e-cigarettes is increasing. E-cigarettes are marketed
as an alternative to smoking tobacco that only produces harmless water vapor,
with no adverse impact on indoor air quality. However, published literature
seems to show that e-cigarettes are not harmless.1 Photo 1 shows an e-cigarette
user exhaling a dense visible aerosol into the surrounding air. This visible aerosol
consists of condensed submicron liquid droplets, which contain many chemicals
including some that are carcinogenic, such as formaldehyde, metals (cadmium,
lead, nickel), and nitrosamines.
Figure 1 is a schematic of typical e-cigarette compoWhat are the chemical emissions from e-cigarettes?
nents. E-cigarettes contain a liquid, typically propylene
We searched through the published literature for inforglycol and/or glycerol, that include varying amounts of
mation on the chemical emissions from e-cigarettes.
nicotine (e.g., 0 to 36 mg/mL) as well as flavorants. A
We then used these chemical emissions to calculate the
wicking material is used to transport the liquid by capil- direct exposure to users and the indirect (passive) expolary action from a reservoir to the heater. When the user sure to non-users, with usage and exposure assumpdraws on the e-cigarette, a sensor detects the draw and
tions selected to produce worst-case exposure scenarios.
a microprocessor activates the heater,
For both the direct and indirect expowhich vaporizes the fluid to produce a
sures, we calculated the hazard quotients
saturated vapor at an elevated temperaas the ratio of the calculated exposures
ture (i.e., > 350°C [662°F] in the center
to both cancer and non-cancer health
2). Propylene glycol,
of the heating unit
exposure guidelines. Hazard quotients in
glycerol, and nicotine are liquids with
excess of 1.0 indicate a health risk.
relatively high boiling points: propylene
The paper by Goniewicz et. al.3 contained the largest study of chemical
glycol (188°C [370°F]), glycerol (290°C
emissions from e-cigarettes and forms
[554°F]), and nicotine (247°C [477°F]).
the primary basis for our analyses. In this
Consequently, the vaporized fluid
paper the chemical emissions of 11 chemimmediately condenses upon leavicals, including carbonyl compounds,
ing the heating element, forming an
volatile organic compounds, tobacco
aerosol of submicron spherical liquid
pHOtO 1: e-cigarettes do not produce a
specific nitrosamines, and heavy metals
droplets with the visible appearance of
vapor (gas), but rather a dense visible
were measured from 12 different e-cigasmoke or fog.
aerosol of liquid sub-micron droplets
rettes. Each e-cigarette was tested three
While the word vapor is used to
consisting of glycols, nicotine, and other
chemicals, some of which are carcinogenic
times. A total of 150 puffs (70 mL/puff)
describe what e-cigarettes produce, and
(e.g., formaldehyde, metals, nitrosamines).
were directly vaporized into the analytivaping is a term used to describe the
cal samplers from an e-cigarette attached to a mechaniprocess of inhaling from an e-cigarette, the emissions
cal smoking machine. For our exposure analyses we
out of the mouthpiece are not actually a vapor, which
included seven of the 11 chemicals studied by Goniewicz
is a gas, but rather they are primarily an aerosol. This
aerosol consists of submicron particles of the condensed
vapor of glycols containing the nicotine and flavorants.
Francis (Bud) J. Offermann, P.e., CIH, is president of Indoor environmental engineering in
So users are not vaping, but rather they are aerosolizing. San Francisco.
38

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