Volatility Characteristics of Electronic Cigarette Aerosols
Transcript of Volatility Characteristics of Electronic Cigarette Aerosols
Volatility Characteristics of
Electronic Cigarette Aerosols
Jacob Swanson1,2, Noah Bock1,2, Will Northrop1
1Dept. of Mechanical Engineering
University of Minnesota – Twin Cities
2Dept. of Integrated Engineering
Minnesota State University – Mankato
2015 Cambridge Particle Meeting
E-Cigarettes (“E-Cigs”) produce an inhalable
aerosol by vaporizing a mixture of liquids
• Nearly all E-cigs use battery to power a heating coil in
contact with a wicking material saturated with E-liquid
• Some are disposable.
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Four standard “E-liquid” constituents
• Glycerol, C3H8O3
– Produces aerosol that resembles smoke
• Propylene Glycol, C3H8O2
– Nicotine carrier, reduces viscosity
• Nicotine (0 – 24 mg·mL-1)
– Generally pharma grade
• Flavoring
– FDA approved PG-based food flavoring
Glycerol
Propylene glycol
Nicotine
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E-cigs are emerging as a safe
alternative to tobacco cigarettes
• Manufacturers claim E-cigs to be safe
(no “toxic chemicals”)
• User perception of safety: 50% say
“safer” vs 2% say “less safe” in the UK
(http://www.ash.org.uk/)
• 2.5 million E-cig users compared to 45
million smokers in the U.S. (3 mil+ in
the UK)
• 13% of high school students use E-cigs
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Experimental objectives
• Construct apparatus that allows
continuous, automated use of a typical
E-cig
• Characterize size, concentration, and
composition particles in E-cig aerosol
• Explore the impact of E-liquid
additives and power on E-cig aerosol
• Determine temporal variability of
aerosol properties
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Battery powered E-cig apparatus
Air in
Aerosol out
Solenoid
Kanthal (FeCrAl)
heating coil
Cotton wick
Battery
enclosure
20 mm
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Battery powered E-cig apparatus
Air in
Aerosol out
Solenoid
Kanthal (FeCrAl)
Heating Coil
Cotton Wick
Battery
Enclosure
20 mm
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Primary limitations: battery life and
E-liquid consumption (~ 10 puffs)
E-Smoking Cycle Simulator (E-SCSTM)
+ -4 V
DC Power Supply
Air in
Aerosol out
5 V input signal
Syringe pump
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Experimental apparatus and instruments
HEPA MFC
DAQ
E-cig
LII
CS
Vent
DilutionCPC
EEPSThe MFC controller pulses
in synchronization with the
E-cig to simulate a user
taking a puff
20 L/min, 0.1 Hz, 3 s pulse
10 L/min
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1500:1
Flavoring and nicotine content have
little impact E-particleTM emissions
1.E+07
1.E+08
1.E+09
1.E+10
5 50 500
dN
/dlo
gD
p,
part
/cm
3
Dp, nm
PG/VG Mix
Flavored No Nicotine
Flavored With Nicotine
Concentrations ~ 1 x 109 particles/cm3 ~ same as tobacco smoke
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The following slides all show
“solid particles” measured
downstream of a catalytic stripper
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1. Averages of 10 puffs
2. Extended evaluation of the life of
the coil
0.0E+00
5.0E+05
1.0E+06
1.5E+06
2.0E+06
100 102 104 106 108 110
Co
nc
en
tra
tio
n, p
art
/cm
3
Puffs
Puff sequence shows highly repeatable
solid E-particle emissions
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Increasing power increases solid particle
emissions; flavoring has little effect
0.E+00
2.E+06
4.E+06
6.E+06
8.E+06
1.E+07
1 10 100
dN
/dlo
gD
p, p
art
/cm
3
Dp (nm)
PG/VG 18 W
PG/VG 13 W
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1 10 100
Dp (nm)
Flavor No Nicotine 13 W
Flavor With Nicotine 13 W
PG/VG 13 W
0.0E+00
5.0E+05
1.0E+06
1.5E+06
2.0E+06
0 100 200 300 400
Co
nc
en
tra
tio
n, p
art
/cm
3
Puffs
Small variation likely due to inconsistent wick saturation
400 puffs shows solid particle emissions
are relatively stable over coil life
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0.E+00
1.E+06
2.E+06
3.E+06
0 200 400 600
Co
nc
en
tra
tio
n, p
art
/cm
3
Puffs
0 200 400 600
Puffs
Flavored E-liquids with and without nicotine
show similar results to standard PG / VG
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Flavor, no nicotine Flavor, with nicotine
LII does not respond to solid E-particles,
suggesting they are not primarily carbon
0
5
10
15
20
25
0 100 200 300
Mass c
on
cen
tra
tio
n,
µg
/m3
Puffs
EEPS LII
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Solid E-particles were collected on silver
membrane filters for Laser Induced
Breakdown Spectroscopy (LIBS) analysis
• ~ 3 µg/m3 for 3 seconds @ 2.6 L/min = 0.39 ng/puff
• 350 puffs
• ~ 1 µg of solid particles per cm2 of filter
CSHEPA MFC
DAQ
E-cig
Filter Area = 0.128 cm2
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LIBS results not conclusive – only
calcium identified above LOD
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0
1000
2000
3000
Ag 328 Ag 338 Ca Cr Rb
Inte
ns
ity (
a.u
.)
Flavored with nicotine Unloaded filter
We thank TSI for loan of the LIBS for this work
Summary
• Semi-volatile E-particles (~ 60 nm in size) are emitted in extremely high concentrations
• 10 nm solid particles are emitted in lower concentrations (1 x 106 part/cm3) and their composition is unknown
• Time (# puffs), E-liquid, flavoring, nicotine all had relatively little impact of solid and semi-volatile E-particle emissions
• Future work includes better LIBS analysis and FTIR detection of gases of interest (HCHO, N2O)
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