ASHRAE Journal - June 2014 - 39

Column Iaq applIcatIons

et.al.,3 that had both significant emission rates and relLED: Lights Up When the User
Microprocessor:
Heater: Vaporizes E-Cigarette
Draws on the E-Cigarette
evant health-based exposure guidelines. Schripp et. al.2
Controls Heater and LED Fluid from Heated Wick
Battery
measured the emission rates of propylene glycol from
three e-cigarettes.
Table 1 summarizes the minimum and maximum chemical emissions rates for nine chemicals in terms of mass
(µg) of chemical per 150 puffs (70 mL/puff). The dominant
Sensor: Detects
chemical emitted was propylene glycol, with a range of
When User Draws Mouthpiece (Condenser): Vapors
250,950 to 828,750 µg/150 puffs. The chemical with the
Condense into an Aerosol of Liquid
Sub-Micron Droplets of E-Cigarette Fluid
next highest emission rate was nicotine, for which we
Figure 1: Schematic of the typical components found in an e-cigarette.
assumed a concentration of 24 mg/mL of nicotine in propylene glycol, yielding 5,770 to 19,060 µg/150 puffs.
Are the chemical emissions from e-cigarettes a
Table 1 Chemical emissions of selected compounds from e-cigarettes for
health risk? We used the maximum chemical emisexposure analyses.
sions in Table 1 to calculate the direct exposure to users
ChemiCal emissions
( µg/150 puFFs - 70 ml/puFF) inDireCT exposure
and the indirect (passive) exposure to non-users,
ChemiCal
with the following usage and exposure assumptions,
Minimum
Maximum
which were selected to produce worst-case exposure
aCeTalDehyDe
2.0
13.6
scenarios.
aCrolein
<0.02
41.9
Direct Exposure Assessment. The median puffs/day
FormalDehyDe
3.2
56.1
by e-cigarette users was assumed to be 175 puffs/day with
CaDmium
<0.04
0.22
a puff volume of 70 mL/puff. The respiratory absorption
leaD
0.03
0.57
of the inhaled vapor was assumed to be 100% for all comniCkel
0.11
0.29
pounds. We assumed a zero exposure other than the vapor
niCoTine
5,770
19,060
that was directly inhaled (i.e., no indirect exposure).
nnk a
<0.0001
0.028
Indirect (Passive) Exposure Assessment. We modeled
propylene glyCol
250,950
828,750
exposures for a small office space (i.e., 20.9 m2 [225 ft], 2.4
a
NNK, 4-(n-nitrosomethylamino)-1-(3-pyridyl)1-butanone.
m [7.9 ft] ceiling), with a low outdoor air ventilation rate of
0.3 h-1 (assuming openable windows
Table 2 Hazard quotients associated with the direct exposures of e-cigarette users and the indirect (passive)
closed and no mechanical ventilation,
exposures of non-users.
so there is only outdoor air infiltraexposure CriTeria
DireCT exposure
inDireCT exposure
tion) and no contaminant removal
ChemiCal
nSRL
CReL
HQ a
HQ a
HQ a
HQ a
other than ventilation. We assumed
(µg/day)
(µg/m3)
nSRL
CReL
nSRL
CReL
continuous occupancy for eight hours
aCeTalDehyDe
90
140
0.18
0.01
0.004
0.0001
by two occupants; one e-cigarette user
aCrolein
n/A
0.35
n/A
7.0
n/A
0.17
(125 puffs in 8 hours, 70 mL/puff) and
FormalDehyDe
40
9
1.64
0.36
0.04
0.009
one non-user. For this assessment
we assumed that 100% of the inhaled
CaDmium
0.05
0.02
5.13
0.64
0.12
0.015
vapor by the user was exhaled into the
leaD
0.5
0.15
1.33
0.22
0.03
0.005
indoor air and the respiratory absorpniCkel
0.8
0.05
0.42
0.34
0.008
0.007
tion by occupants of the exhaled
niCoTine
n/A
5
n/A
222
n/A
5.4
vapor in the indoor air was 100% for
nnk b
0.014
n/A
2.36
n/A
0.05
n/A
all compounds. We assumed a zero
propylene glyCol
n/A
50
n/A
967
n/A
23
exposure when away from work.
For cancer health effects we used the aHazard quotients expressed as the ratio of the calculated exposure to the NSRL and CREL health exposure guidelines, with values
above 1.0 bolded.
California Office of Environmental
b
NNK, 4-(n-nitrosomethylamino)-1-(3-pyridyl)1-butanone.
Health Hazard Assessment,4 No
J u n e 2014

ashrae.org

ASHRAE JouRnAl

ASHRAE Journal - June 2014

Table of Contents for the Digital Edition of ASHRAE Journal - June 2014