United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711 ^/|V
Research and Development
EPA/600/S3-85/008 Apr. 1985
v>EPA Project Summary
Sampling of Automobile
Interiors for Organic Emissions
David Dropkin
A study was undertaken to deter-
mine the concentrations of N-nitrosa-
mines (specifically N-nitrosodimethyl-
amine and N-nitrosomorpholine) and
hydrogen cyanide, as well as to iden-
tify other volatile organic compounds
that were emitted from the interiors
of the new cars tested, before, while,
and after the cars were heated. The
three cars tested were placed in an
enclosed shed and then heated by us-
ing infrared tungsten lamps focused
on their interiors to simulate the
heating effect of sunlight. The
gasoline tanks of the cars were
removed and their fuel lines emptied
for safety reasons and to eliminate
gasoline vapors from interfering with
any of the analyses. The air inside the
cars and inside the shed was sampled
during the entire temperature rise or
"heat buildup" cycle (from ambient to
60°C). The air samples were pulled
through cartridges containing ab-
sorbents such as Thermosorb (used
specifically to collect N-nitrosamines)
and Tenax (used to collect volatile
organic compounds), as well as
through impingers and into Tedlar
bags to analyze for hydrogen cyanide.
The results obtained revealed low
concentrations of N-nitrosodimethyl-
amine and N-nitrosomorpholine in the
car interiors during the heating proc-
ess, but higher concentrations of
these N-nitrosamines outside of the
cars (in the shed). No hydrogen
cyanide was detected inside or out-
side the two cars tested for this com-
pound. Peaks on the GC/MS system
that were associated with residual
gasoline vapors and laboratory
solvents such as methylene chloride
and tetrachloroethylene indicated that
no meaningful comparison could be
made between the car interior and
shad interior emissions.
This Pro/act Summary was
developed by EPA's Atmospheric
Sciences Research Laboratory,
Research Triangle Park, NC, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Low concentrations of potentially car-
cinogenic organic vapors such as vinyl
chloride, N-nitrosamines, and benzene
have previously been identified in the in-
teriors of many cars driven in this coun-
try. The emissions of these vapors have
been attributed to the materials and
adhesives used in the interiors of cars for
seating, dashboard, and trim. Many dif-
ferent types of plastics, rubber, vinyl
fabrics, and adhesives are used in a di-
versity of manufacturing processes to
reduce the costs of producing new cars,
and to reduce the weight of these cars
(for improved gas mileage). It is,
therefore, useful to investigate the poten-
tially carcinogenic interior emissions from
these cars. The purpose of this study was
to identify and quantitate the N-nitrosa-
mines and hydrogen cyanide and to
survey the other volatile organic com-
pounds produced from the interior emis-
sions of the new (1980-81) model cars.
Procedure
Three cars, a 1980 Buick Skylark, 1980
Mazda GLC, and 1981 Plymouth Horizon,
were tested. These cars were chosen
because of their availability. Each car was
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placed in an enclosed shed; and air
samples from the interior and exterior
(shed air) of the car were taken before,
while, and after the car was heated. The
cars were heated by six tungsten filament
heat lamps focused on the interior to
simulate the "heat buildup" caused by ex-
posure to sunlight.
The enclosed shed (Figure 1) used for
testing provided a controlled environment
with a reduced potential for outdoor air
contamination. To prevent gasoline vapor
contamination the gas tanks of the cars
were removed and their fuel lines were
emptied.
The nominal temperature rise in the in-
terior of a car on a typical hot summer
day was determined by placing a car out-
side in the parking lot and monitoring the
interior and outdoor temperature each day
for 3 days. This temperature range was
then used as the basis for setting up the
six tungsten heat lamps to heat the cars.
Exposing the cars to a 2-day heating and
cooling cycle without purging the interior
air was performed to simulate a "worst
case" situation in which the N-nitrosa-
mine and hydrogen cyanide emissions
might be increased.
A Thermosorb sampling system was
used to collect potential N-nitrosamine
emissions, specifically N-nitrosodimethyl-
amine (NDMA) and N-nitrosomorpholine
(NMOR). This system has been demon-
strated as the method of choice for retain-
ing 100 percent of any pre-loaded nitro-
samines. Tenax G.C. has been in general
use for the trapping of volatile organic
compounds and thermal desorption of the
trapped material onto a GC/MS system to
obtain a qualitative analysis. Two
methods for the trapping or collecting and
analysis of hydrogen cyanide have been
attempted. By one method, air is col-
lected in impinger-type scrubbers contain-
ing 25 ml of 0.625 NNaOH and analyzed
for HCN using a colorimetric procedure.
By the other method, air is collected in a
Tedlar bag, and an aliquot of the bag
contents is then analyzed by using a gas
chromatograph coupled to a chemilumi-
nescent detector. Both these methods
were modified and adapted for this pro-
gram to analyze for hydrogen cyanide in
automobile exhaust.
Conclusions
N-nitrosamines were detected in the in-
terior air of all the cars tested while the
cars were heated and at the steady-state
60°C (interior) temperature. The levels of
N-nitrosamines measured inside the cars
ranged from an average of < 0.04 to 0.37
Tedlar Roof
Exhaust Fan
Quick-Connects
to Sample Lines
Aluminum Floor and Walls
Figure 1. Shed. Horiba, Inc., model EPS76, volume: 1600ft3.
/ig/m3 for NDMA and from an average of
<0.06 to 0.25 pg/m3 for NMOR; the
limits of detection were <0.04 /tg/m3 for
NDMA and <0.06 /ig/m3 for NMDR. The
concentrations of these N-nitrosamines
measured in the shed, however, were an
average 2 times greater than those
measured in the interior. The N-nitro-
samine levels measured when the cars
were subjected to the "worst case" con-
ditions were higher in most cases than the
interiors were heated for the 1 day test
cycle. The levels of the N-nitrosamines
measured in the shed were, again, usually
greater than those measured in the in-
terior. Measurements of N-nitrosamines in
the trunk of the Buick Skylark were on
average 1.5 to 2 times greater than the
concentration measured in the shed.
These values, however, were obtained
even when the spare tire was removed.
indicating that other possible sources of
N-nitrosamines must be present. Available
resources would not permit a compre-
hensive, statistical significant examination
of the N-nitrosamine emissions in the in-
teriors of new cars.
No HCN was detected in either the in-
terior of the cars tested or in the shed
during the entire heating cycle.
No conclusion could be made concern-
ing the emission of other volatile organic
compounds due to the high background
obtained from laboratory solvent emis-
sions, high concentrations in the testing
area of Freon contaminant and other
hydrocarbons, especially residual gasoline
vapors.
Recommendations
In future testing, emissions, of com- t
pounds such as vinyl chloride, aldehydes.
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and ketones should also be measured in
this type of controlled environment. In-
stead of purging the shed and car interior
with air from the room surrounding the
shed, hydrocarbon-free air, nitrogen, or
helium should be used in order to define
the volatile organic emissions.
The EPA author David Dropkin is with the Atmospheric Sciences Research
Laboratory, Research Triangle Park, NC 27711.
The complete report, entitled "Sampling of Automobile Interiors for Organic
Emissions, "(Order No. PB 85-172 567/AS; Cost: $8.50, subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, v'A 22161
Telephone: 703-487-4650
The author can be contacted at:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
-l, U.S. GOVERNMENT PRINTING OFFICE: 1985-559-016/27038
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