United States
Environmental Protection
Agency
Environmental Monitoring Systems
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S4-85/079 Jan. 1986
f/EPA Project Summary
Development of a Sampler for
Paniculate-Associated and Low
Volatility Organic Pollutants in
Residential Air
J. E. Howes, Jr., T. L. Merriman, C. A. Ortiz, A. R. McFarland, and M. R. Kuhlman
Little information is currently avail-
able on the effects indoor air quality
may have on public health. Since most
of the population spends the majority of
each day indoors, indoor air quality may
be a more important component of the
risk to which the public is subjected
than is outdoor air quality. A recent
trend towards energy-efficient building
construction typically results in signif-
icant reductions in the indoor-outdoor
air exchange rate. This trend, coupled
with the increasing use of alternative
heating sources in homes, results in a
potential for concentrations of incom-
plete combustion products to achieve
undesirable levels.
Current analytical techniques for
these organic compounds require sam-
pling of large volumes of air with a
filter/sorbent combination. The use of
available ambient, high-volume air sam-
plers in occupied residences is not
practicable due to the noise they emit
and their very high flow rates. There is a
need, therefore, to develop an air sam-
pler suitable for in-house usage so that
the quality of indoor air can be ade-
quately assessed.
The full report describes the devel-
opment of a sampler for particulate-
associated and low-volatility organic
pollutants in residential air. The per-
formance of the sampler inlet, which is
compatible with the proposed PM-10
regulations for paniculate sampling, is
documented under a variety of condi-
tions of interest. The details of con-
struction of the sampler and the result-
ing acoustic performance of the unit are
described. While the unit described in
the full report can perform the task it
has been designed for, several design
enhancements are recommended which
would- result in an improved residential
sampler.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Research Triangle
Park. NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering in-
formation at back).
Introduction
Until recently, research and monitoring
efforts have generally focused on assess-
ing and improving the quality of air in the
ambient (outdoor) environment. However,
concern about the effects of indoor air
quality on the public welfare has recently
become more pronounced. Some reasons
for this concern are the variety of pol-
lutants that may arise from commercial
products used indoors, the increase in
woodburning as a heating source, and
the energy conservation measure of
reducing the air exchange rate in build-
ings. Some recent studies have shown
that indoor pollutant levels contribute far
more to total exposure than outdoor
pollutant levels.
For many organic compounds of inter-
est, methodology is not available to
determine airborne pollutant levels in
indoor environments. Because some of
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these compounds pose a health risk at
very low concentrations, there is the need
to sample air at the highest practicable
rate in order to collect sufficient material
for analysis. This need has not yet been
met satisfactorily. The sampling rate of
existing systems does not provide ade-
quate sample mass for detection at levels
prevalent in indoor air, appropriate equip-
ment is not available, or existing samplers
{usually ambient types) are not suitable
for indoor applications because of size,
noise, etc.
Thus, in this project, an air sampler was
developed for indoor use that can collect
quantities of particulate-bound and va-
por-phase organic compounds sufficient
for detailed organic analysis and biolog-
ical screening. The particulate and vapor
phase samples of the semi-volatile com-
pounds are collected by the sampler in a
manner that minimizes artifact formation
and background interferences that would
be detrimental to subsequent analyses
and bioassays. The inlet provided for the
system is designed with a nominal 10/um
cut point consistent with proposed re-
quirements for PM-10 ambient panic-
ulate samplers. The resulting sampler is
quite transportable and relatively unob-
trusive. Its low maintenance require-
ments and high reliability also render it
suitable for air sampling in residential
environments.
Procedure
Design requirements for the sampler
were determined. These requirements
include the ability to collect sufficient
material for both chemical analyses and
bioassays, the ability to collect both vapor
and particulate phase organic compounds,
flow rate sufficiently low to perturb the
indoor environment only minimally, high
collection efficiency and minimal back-
ground interferences, noise level low
enough to be acceptable in the home,
ease of transport, high reliability, and low
maintenance.
To meet these requirements, the fol-
lowing criteria were set. An 8 cfm flow
rate was chosen as most appropriate.
This flow rate gives two-hour time reso-
lution for most compounds of interest and
provides sufficient sample for bioassay in
eight hours. ANSI 51.2 noise standards
(or a noise criterion of 35) were chosen.
These standards allow sampler noise
approximately equivalent to that in a
quiet conference room or bedroom. A
filter/sorbent sampling module employ-
ing a quartz fiber filter and a sorbent bed
of polyurethane foam (PUF) and/or XAD-
2 resin were incorporated. Additionally, a
removable PM-10 inlet was incorporated.
The starting point for the sampler
development was the existing EPA PUF
sampler currently manufactured by Gen-
eral Metal Works. This sampler was then
modified to meet the criteria above. A
PM-10 inlet was separately designed and
tested.
Results
Results obtained during building and
testing the prototype air sampler can be
summarized as follows:
• PM-10 Inlet—The inlet for aerosol
particles achieves a cut point of 10 /jm
aerodynamic diameter and is reason-
ably insensitive to small variations in
the sampling flow rate. Carryover of
large particles and particle bounce
have been essentially eliminated in
the inlet.
• Sorbent Bed—The sampler is capable
of collecting adequate samples on the
sorbent bed for limited time resolution
of the species of interest at the design
flow rate.
• Acoustics—A noise criterion (NC) of
NC = 45 was achieved versus the
stringent design goal of NC = 35. A few
minor design changes to eliminate a
spurious whistle and increase the
baffling in the motor cooling chamber
should permit reaching NC = 37.
• Motor Cooling—The motor cooling air
must be carefully separated from the
hot vacuum exhaust air in order to
prevent air recirculation and subse-
quent overheating of the motor.
An air sampling system suitable for use
in residential environments has been
developed and evaluated. The flow rate
achievable with this device is adequate
for at least eight hour time resolution of
typical concentrations of most semi-vol-
atile organics of interest in either the
particulate or the vapor phase. The system
is quiet, transportable, and relatively
unobtrusive.
Overall, the prototype has proven the
basic design to be effective. The design
goals can be met with minor redesign,
and limited additional testing would be
required to confirm the effectiveness of
the modifications.
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J. E. Howes, Jr., is currently with Environmental Monitoring and Services, Inc.,
NewburyPark. CA 91320; T. L Merriman andM. R. Kuhlman are with Battelle's
Columbus Laboratories, Columbus, OH 43201; and C. A. Ortiz and A. R.
McFarland are with Texas A&M University, College Station, TX 77843.
Nancy K. Wilson is the EPA Project Officer (see below).
The complete report, entitled "Development of a Sampler for Paniculate-
Associated and Low Volatility Organic Pollutants in Residential Air," (Order No.
PB 86-131 950/AS; Cost: $9.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-85/079
0000529 PS
U S ENVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO It 60604
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