EPA/600/8-89/074
August 1989
INDOOR AIR SOURCES:
USING SMALL ENVIRONMENTAL TEST CHAMBERS TO
CHARACTERIZE ORGANIC EMISSIONS FROM INDOOR
MATERIALS AND PRODUCTS
by
Bruce A. Tichenor
U, S. Environmental Protection Agency
Air and Energy Engineering Research Laboratory
Indoor Air Branch
Research Triangle Park, NC 27711
AIR AND ENERGY ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1, REPORT NO, 2
EPA/600/8-89/074
3. RECIPIENT'S ACCESSION NO,
PR 90 1 1 A 1 3 1 lAt
4. title and subtitle Indoor Air Sources:
Using Small Environmental Test Chambers to Charac-
terize Organic Emissions from Indoor Materials and
Products
E, REPORT DATE v
August 1989
6. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
Bruce A. Tichenor
8. PERFORMING ORGANIZATION REPORT NO.
9, PERFORMING OROANIZATION NAME AND ADDRESS
See Block 12
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
NA (inhouse)
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 1-7/89
14. SPONSORING AGENCY CODE
EPA/600/13
Author Tichenor,s Mall Drop is 54; his phone number is 9I9/541_
is, abstract The report describes procedures for determining organic emission rates
from indoor materials/products using small environmental test chambers. The tech-
niques presented are useful for both routine product testing by manufacturers and
testing laboratories and for more rigorous evaluation by indoor air quality resear-
chers.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. cosati Field/Group
Pollution Measurement
Test Chambers
Emission
Organic Compounds
Gas Chromatography
Sampling
Pollution Control
Stationary Sources
Emission Rates
Indoor Air Quality
Indoor Materials/Pro-
ducts
13 B
14 B
14G
07C
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport}'
Unclassified
21. NO, OF PAGES
U f
20. SECURITY class (This page)
Unclassified
22. PRICE
EPA Form 2220-1 J9-73J
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse
ment or recommendation for use.
ii
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PREFACE
In October 1986, Congress passed the Superfund Amendments and
Reauthorization Act (SARA, PL 99-499} that Includes Title IV - The Radon Gas
and Indoor Air Quality Research Act. This Act directs that the Environmental
Protection Agency (EPA) undertake a comprehensive indoor air research program
with the ultimate goal of providing information on indoor air pollution to the
public.
EPA publishes the results of Its Indoor air research activities In the
INDOOR AIR technical report series. The series consists of scientific and
technical reports covering five subject categories: Sources, Measurement, Health,
Assessment, and Control. These reflect the organization of the Indoor Air
Research Program within EPA's Office of Research and Development;
A. Sources of Indoor Air Pollution
B. Building Diagnosis and Measurement Methods
C. Health Effects
D. Exposure and Risk Assessment
E. Building Systems and Indoor Air Quality Control Options.
Research program requirements under Superfund Title IV are specific. They
include characterizing and monitoring the sources and levels of indoor air
pollution; developing instruments to collect indoor air quality data; and
studying high risk building types. The statute also requires research on the
effects of indoor air pollution on human health. Additional research is required
to develop mitigation measures to prevent or abate indoor air pollution; and to
develop methods to both assess the potential for soil gas contamination of new
construction, and examine design measures to avoid indoor air pollution.
EPA is directed to undertake this comprehensive research and development
effort not only through in-house work but also in coordination with other Federal
agencies, state and local governments, and private sector organizations having
an interest in indoor air pollution.
For each of its technical reports the Office of Research and Development
publishes a Project Summary. A Project Summary is a short synopsis of the key
research findings of a research report, and is a means of informing the public
about reports available from the National Technical Information Service and not
printed for outside distribution. Project Summaries for all reports in the
INDOOR AIR series are available from:
U.S. Environmental Protection Agency
Center for Environmental Research Information
26 W. Martin Luther King Drive
Cincinnati, OH 45268
i i i
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CONTENTS
Preface . . . i i i
Figures vi
Tables vi
1. Introduction 1
A. Scope 1
B. Testing objectives .............................. 2
C. Mass transfer considerations 2
D. Use of the results . . . 4
2. Facilities and equipment 5
A. Environmental test chambers 5
B. Environmental measurement and control 8
3. Sample collection and analysis 10
A. Sampling devices ................................. 10
B. Sample collection media 11
C. Organic analysis instrumentation 11
D. Standards generation and system calibration 12
4. Experimental design . 13
A. Test objectives 13
B. Critical parameters 13
C. Product history 14
D. Test matrix . 14
5. Experimental procedures 16
A. Emissions composition 16
B. Headspace analysis 16
C. Chamber testing 17
D. Sampling and analysis 19
6. Data analysis 22
A. Environmental data 22
B. Gas chromatography data 23
C. Emission factor calculations 24
7. Quality assurance/quality control 28
8. Reporting test results 31
References 33
Bibliography 34
Preceding page blank v
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FIGURES
Number Page
1 Schematic of example small chamber test facility 6
2 Chamber concentration vs. time -- wood stain 21
3 Example chamber concentration curve for a wet source
(total organics from wood stain) 27
TABLES
1 Example test matrix 15
2 Example environmental data summary 22
3 Example data quality objectives/acceptance criteria .. 29
vi
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SECTION 1
INTRODUCTION
A. SCOPE
The use of small environmental test chambers to develop
emission characteristics of indoor materials and products is
still evolving. Modifications and variations in equipment,
testing procedures, and data analysis are made as the work in the
area progresses. Until the interested parties agree upon
standard testing protocols, differences in approach will occur.
The purpose of this report is to provide assistance by describing
equipment and techniques suitable for determining organic
emissions from indoor materials. Specific examples are provided
to illustrate existing approaches; these examples are not
intended to inhibit alternative approaches or techniques.
Small chambers have obvious limitations. Normally, only
samples of larger materials (e.g., carpet) can be tested. Small
chambers may not be applicable for testing complete assemblages
(e.g., furniture). Small chambers are also inappropriate for
testing combustion devices (e.g., kerosene heaters) or activities
(e.g., use of aerosol spray products). For some products, small
chamber testing may provide only a portion of the emission
profile of interest. For example, the rate of emissions from the
application of high solvent materials (e.g., paints, waxes) via
brushing, spraying, rolling, etc. is generally higher than the
rate during the drying process. Small chamber testing cannot be
used to evaluate the application phase of the coating process.
The report does not provide specific guidance for
determining emissions of formaldehyde from pressed wood products,
since large chamber testing methods for such emissions are well
developed and widely used (Myers, 1984), It is possible,
however, that the guide could be used to support alternative
testing methods.
While the ultimate purpose of any evaluation of indoor
materials is to determine whether the emissions can contribute to
health or comfort problems, this report is applicable only to the
determination of the emissions themselves. The effect of the
emissions (e.g., toxicity) is beyond the scope of the report.
Within the context of the 1 imitations discussed above, the
purpose of this report is to describe the methods and procedures
for determining organic emission rates from indoor
materials/products using small environmental test chambers. The
techniques described are useful for both routine product testing
by manufacturers and testing laboratories and for more rigorous
evaluation by Indoor Air Quality (IAQ) researchers.
1
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B. TESTING OBJECTIVES
The use of small chambers to evaluate organic emissions from
indoor materials has several objectives:
- develop techniques for screening of products for
organic emissions;
- determine the effect of environmental variables (i.e.,
temperature, humidity, air exchange) on emission rates;
- rank various products and product types with respect to
their emissions profiles (e.g., emission factors, specific
organic compounds emitted);
- provide compound-specific data on various organic sources
to guide field studies and assist in evaluating indoor air
quality in buildings;
- provide emissions data for the development and
verification of models used to predict indoor
concentrations of organic compounds;
- develop data useful to manufacturers and builders for
assessing product emissions and developing control options
or improved products.
C. MASS TRANSFER CONSIDERATIONS
Small chamber evaluation of emissions from indoor materials
requires consideration of the relevant mass transfer processes.
Three fundamental processes control the rate of emissions of
organic vapors from indoor materials; 1) evaporative mass
transfer from the surface of the material to the overlying air,
2) desorption of adsorbed compounds, and 3) diffusion within the
material,
Evaporative Mass Transfer
The evaporative mass transfer of a given organic compound
from the surface of the material to the overlying air can be
expressed as;
E = km (VPs - VPa ) (1)
Where, E = Emission rate, mg/hr
km = Mass transfer coefficient, mg/mm Hg-hr
VPs = Vapor pressure at the surface of the material, mm Hg
VPa = Vapor pressure in the air above the surface, mm Hg
Thus, the emission rate is proportional to the difference in
vapor pressure between the surface and the overlying air. Since
the vapor pressure is directly related to the concentration, the
emission rate is proportional to the difference in concentration
between the surface and the overlying air. The mass transfer
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coefficient is a function of the diffusion coefficient (in air)
for the specific compound of interest, the level of turbulence
in the boundary layer above the surface of the material, and the
thickness of the boundary layer.
Desorption
The desorption rate of compounds adsorbed on materials can
be determined by the retention time (or average residence time)
of an adsorbed molecule (Levine, 1978):
t = to e-«/*T (2)
Where, t = Retention time, sec
To = Constant with a typical value from 10"12 to 10"15 sec
Q = Molar enthalpy change for adsorption or adsorption
energy, cal/mole
R = Gas constant, 1.987 cal/mole-K
T = Temperature, K
The larger the retention time, the slower the rate of desorption.
Diffusion Within the Material
• The diffusion mass transfer within the material is a
function of the diffusion coefficient (or diffusivity) of the
specific compound. The diffusion coefficient of a given compound
within a given material is a function of the compound's physical
properties (e.g., molecular weight, size), temperature, and the
structure of the material within which the diffusion is
occurring. The diffusivity of an individual compound in a
mixture is also affected by the composition of the mixture.
Variables Affecting Mass Transfer
While a detailed discussion of mass transfer theory is
beyond the scope of this guide, it is necessary to examine the
critical variables affecting mass transfer within the context of
smal1 chamber testing:
Temperature--
Temperature affects the vapor pressure, desorption rate, and
diffusion coefficients of the organic compounds. Thus,
temperature impacts both the mass transfer from the surface
(whether by evaporation or desorption) and the diffusion mass
transfer within the material. Increases in temperature cause
increases in the emissions due to all three mass transfer
processes.
Air Exchange Rate--
Air exchange rate (ACH or hr*1) is defined as the volume of
outdoor air that enters the indoor environment in 1 hour divided
by the volume of the indoor space. The air exchange rate
indicates the amount of dilution and flushing that occurs in
indoor environments. The higher the air exchange rate, the
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greater the dilution and the lower the concentration. If the
concentration at the surface is unchanged, a lower concentration
in the air increases the evaporative mass transfer by increasing
the difference in concentration between the surface and the
overlying air.
Air Velocity—
The mass transfer coefficient (km) is affected by the
velocity in the boundary layer above the surface and the level of
turbulence. Generally, the higher the velocity and the higher
the level of turbulence, the greater the mass transfer
coefficient. In a practical sense, above a certain velocity and
level of turbulence, the resistance to mass transfer in the
boundary layer is minimized (i.e., the mass transfer coefficient
reaches its maximum value). In chamber testing, some
investigators prefer to use velocities high enough to minimize
the mass transfer resistance at the surface. For example, air
velocities of 0.3 to 0.5 m/sec have been used in evaluating
formaldehyde emissions from wood products. Such velocities are
higher than those observed in normal residential environments by
Matthews, et al. (1987), where in six houses they observed
velocities with a mean of 0.07 m/sec and a median of 0,05 m/sec.
Thus, other investigators prefer to keep the velocities in the
range normally found indoors. In either case, an understanding
of the effect of velocity on the emission rate is needed in
interpreting small chamber emissions data.
D. USE OF THE RESULTS
It is emphasized that small chamber evaluations are used to
determine source emission rates. These rates are then used in
appropriate IAQ models to predict indoor concentration of the
compounds emitted from the tested material. The concentrations
observed in the chambers themselves should not be used as a
substitute for concentrations expected in full-scale indoor
environments.
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SECTION 2
FACILITIES AND EQUIPMENT
A facility designed and operated to determine organic
emission rates from building materials and consumer products
found indoors should contain the following: test chambers, a
clean air generation system, monitoring and control systems,
sample collection and analysis equipment, and standards
generation and calibration systems. Figure 1 is a schematic
showing an example system with two test chambers.
A. ENVIRONMENTAL TEST CHAMBERS
Small environmental test chambers are designed to permit the
testing of samples of various types of building materials and
consumer products. They can range in size from a few liters to
5 m3. Generally, chambers of more than 5 m3 are considered
"large," Large chambers permit the testing of complete
assemblages (e.g., furniture); they may also be used to evaluate
activities (e.g., spray painting). For the purpose of this
guide, small chambers are assumed to be used to test samples of
larger materials and products, as opposed to full scale materials
or processes.
Chamber Construction
The test chambers should have non-adsorbent, chemically
inert, smooth interior surfaces. Care must be taken in their
construction to avoid the use of caulks and adhesives that emit
or adsorb volatile organic compounds. Electropolished stainless
steel and glass are common interior surfaces. The chamber must
have an access door with airtight, non-adsorbent seals. The
chambers must be fitted with inlet and outlet ports for air flow.
Ports for temperature and humidity probes may also be required.
Ports for sample collection are needed only if the sampling is
not conducted in the outlet air, although sampling in the outlet
is the preferred technique.
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Internal Mixing
The chambers should be designed to ensure adequate mixing of
the chamber air. Low speed mixing fans or multi-port inlet and
outlet diffusers are two techniques that have been used
successfully. One approach for determining if the chamber air is
adequately mixed is to blend a tracer gas (e.g., SFb) with the
inlet air at constant concentration and flow and measure the
concentration in the chamber outlet over time. The chamber
concentration vs. time plot is then compared to the theoretical
curve for a completely mixed chamber:
C = Co (1 - e"Nt ) (3)
Where, C = Chamber concentration, mg/m3
Co = Inlet concentration, mg/m3
N = Air exchange rate, hr"1; N = Q/V, where Q = Flow rate
through chamber, m3/hr, and V = Chamber volume, m3
t = Time, hr
If the measured data closely follow the theoretical curve, the
chamber is well mixed. When the measured data lie above the
theoretical curve, short circuiting of the flow is occurring and
the chamber air is not well mixed. Short circuiting is probably
caused by poor placement of the air inlet and/or outlet ports.
If the measured data fall below the theoretical curve, some of
the tracer gas may be adsorbing on the chamber surfaces, the
chamber may be leaking, or incomplete mixing may be occurring.
Tests to determine the adequacy of mixing should be conducted not
only in an empty chamber, but also with inert substrates of the
types of samples to be tested to ensure that placement of the
samples in the chamber will not result in inadequate mixing.
Quantitative guidance on the mixing is unavailable. One
method might be to "force" the measured data through the
theoretical curve using the chamber volume (V J as a variable.
One could then compare the actual chamber volume to the
"apparent" chamber volume based on the curve fit. A difference
of >10% between the actual and "apparent" volumes mi ght be
considered unacceptable.
Surface Velocity
As discussed in Section 1.C, the velocity near the surface
of the material being tested can affect the mass transfer
coefficient. If it is desired to maximize the mass transfer in
the boundary layer, one should use a relatively high velocity
(e.g., >0.3 m/sec). This will require the use of a fan to direct
the flow along the surface of the material. If the test
objectives require low velocities more representative of indoor
environments, care should be taken to ensure that the technique
used to promote mixi ng in the chambers does not cause excessive
air velocities (e.g., >0.05 m/sec) at the surface of the source
to be tested.
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Temperature Control
Temperature can be controlled by placing the test chambers
in incubator cabinets or other controllable constant temperature
environments.
Small chambers are normally operated without lights. If the
effect of lighting on emissions is to be determined, appropriate
interior illumination should be provided. If lighting is used,
care should be taken to avoid heating of the chamber interior.
Clean Air Generation System
Clean air must be generated and delivered to the chambers.
A typical clean air system might use an oilless compressor
drawing in ambient air followed by removal of moisture (e.g.,
using a membrane dryer) and trace organics (e.g., by catalytic
oxidation units). Other options include gas cylinders or
charcoal filtered outdoor or laboratory air. The amount of air
fl ow required should be calculated before a decision is reached
on the supply system. The required purity o f the air must also
be determined based on the type of samples to be evaluated.
Humidity Control
Humidity of the chamber air is controlled by adding
deionized (or HPLC grade distilled) water to the air stream.
Injection by syringe pumps followed by heating to vaporize the
water can achieve desired humidity levels, although syringe pumps
are prone to breakdown during prolonged, continuous use. Other
types of pumps (e.g., HPLC) might also provide sufficient
accuracy. Humidi f i cation can also be accomplished by bubbling a
portion of the airstream through deionized water at a controlled
temperature (e.g., in a water bath). Coiled lines inside the
constant temperature environment (e.g., incubator) can be used
for inlet temperature equilibration before delivery to the test
chambers.
B. ENVIRONMENTAL MEASUREMENT AND CONTROL
Measurement and control are required for air flow,
temperature, and humidity. Air flow can be automatically
monitored and controlled by electronic mass flow controllers, or
manual flow control (e.g., needle valve, orifice plate) and
measurement (e.g., bubble meter, rotameter) can be used. Some
investigators recommend that the chamber be operated very
slightly above atmospheric pressure and that both atmospheric and
chamber pressure be measured. Temperature control is discussed
above (see Sect ion 2,A). Temperature can be measured
automatically using thermocouples or thermistors; manual dial or
stem thermometers can also be used. Control of humidity depends
on the humid if ication system employed. If liquid injection is
used, water flow is controlled by the pump setting. Control of
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humidity by saturated air requires temperature control of the
water and flow control of the saturated air stream. Humidity can
be measured by several types of sensors, including dew point
detectors and thin-film capacitors. Temperature and humidity
sensors should be located inside the chamber at least 5 cm from
the inside wall and near the midpoint between the air inlet and
outlet ports.
Microcomputer based measurement and control systems can be
used to set air flow rates and monitor temperature, relative
humidity, and air flow during the course of experiments. Analog
signals from temperature, relative humidity, and flow sensors are
converted to digital units that can be stored by a microcomputer-
based system, then processed to engineering units using
appropriate calibration factors. In this way, chamber
environmental data can be continuously monitored, then compiled
and reduced for archival storage or display with minimal operator
effort. Automatic systems are also capable of certain control
functions. Digital signals can be output to control valves or
converted to analog signals and sent out as set point signals to
mass flow controllers. A graphics overlay program can be used to
show current setpoints and measured values on a system schematic
displayed on the microcomputer's monitor.
While automatic systems provide enhanced data collection and
control, they are also expensive and complex. The simplicity and
low cost of manual systems may be preferable under many
circumstances.
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SECTION 3
SAMPLE COLLECTION AND ANALYSIS
Indoor sources of organic emissions vary widely in both the
strength of their emissions and the type and number of compounds
emitted. To fully characterize organic emissions, the sample
CO llect ion/analysis system must be capable of quantitative
collection and analysis of volatile, semivolatile, polar, and
non-polar compounds. Any small chamber sampling and analysis
technique or strategy developed must consider the emission
characteristics of the specific source being evaluated. The
design and operation of sample collection and analysis systems
must be appropriate for the organic compounds (and their
concentrations) being sampled. Such systems generally include
sampling devices (e.g., syringes, pumps), sample collectors
(e.g., syringes, adsorbent media, evacuated canisters), and
instruments to analyze organic emissions (e.g., gas
chromatographs [GCs]). The remainder of this section discusses
the alternatives available for small chamber sampling and
analysis of organic emissions; technical details of specific
systems are not included.
A. SAMPLING DEVICES
The exhaust flow (i.e., chamber outlet) is normally used as
the sampling point, although separate sampling ports in the
chamber can be used. A multiport sampling manifold can be used
to provide flexibility for duplicate samples. A mixing chamber
between the test chamber and the manifold will permit addition
and mixing of internal standard gases with the chamber air
stream. Sampling ports with septums are needed if syringe
sampling is to be conducted. The sampling system should be
constructed of inert material (e.g., glass, stainless steel), and
the system should be maintained at the same temperature as the
test chambers. The exhaust from the sampling system should be
ducted into a fume hood, ensuring that any hazardous chemicals
emitted by the test materials are isolated from the laboratory
environment.
Samples can be drawn into gastight syringes, GC sampling
loops, evacuated canisters, or through sorbent cartridges using
sampling pumps, Gastight syringes and closed loops are
frequently used when chamber concentrations are high and sample
volumes must be small to prevent overloading of the analytical
instrument. Larger volume samples can be pulled through sorbent
cartridges using sampling pumps. Flow rate can be controlled by
an electronic mass flow controller. Experience at EPA suggests
that the sampling flow rate should be 1imited to < 50% of the
chamber flow rate to prevent perturbing the chamber flow. Valves
and a vacuum gauge may be incorporated into the system to permit
verification o f system integrity before samples are drawn. The
entire system can be connected to a programmable electronic timer
to permit unattended sample collection.
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B. SAMPLE COLLECTION MEDIA
If the sample is collected via syringe or closed-loop
sampling, it is injected directly into a GC or other instrument
for analysis. Collection in a sampling bag (e.g., Tedlar) or
vessel (e.g., glass, stainless steel) allows for larger samples.
For many small chamber evaluations of indoor materials, low
concentrations of the compounds of interest require large volume
samples and collection on an appropriate adsorbent medium is
required. Several sorbent materials are available for use,
singly or in combination, including activated carbon, glass
beads, Ambersorb, Tenax, graphitized carbon, and XAD-2, The
selection of the sorbent (or sorbent combination) depends on the
compound(s) to be collected. For example, a sorbent combination
of activated carbon and Tenax, in series, allows quantitative
thermal desorption of compounds with boiling points below 200°C.
Desorption temperatures up to 230°C are commonly used; however,
Tenax artifact formation increases at increasing temperatures.
Graphitized carbon sorbents can be desorbed at temperatures up to
400°C and thus are useful for sampling a much wider range of
compounds than Tenax. While graphitized carbon shows promise, it
is emphasized that limited data are available on its performance
for the wide variety of compounds emitted indoors. XAD-2 resin
can be used to collect compounds considered to be semi- or non-
volatile (i.e., boiling points above 180° C). Additional details
on the selection and use of sorbents can be found in a series of
four EPA reports (Adams, et al., 1977; Gallant, et al., 1978;
Piecewicz, et al., 1979; Harris, et al., 1982).
If sorbent collection is used, the laboratory must be
equipped with appropriate storage capabilities. Airtight glass
tubes or chemically inert bags are both appropriate. Flushing
the storage containers with high purity nitrogen prior to use
will help ensure their cleanliness. Samples should be stored in
a freezer at - 20° C. If possible, sorbent samples should be
desorbed and analyzed wi th in 48 hours of collection.
When sorbents are used for sample collection, desorption and
concentration is necessary. For example, a clamshell oven can be
used to thermally desorb .sorbent cartridges with the vapors fed
to the concentrator column of a purge and trap concentrator that
thermally desorbs the organic compounds to the GC column.
Solvent extraction and liquid injection to the GC can also be
employed. Other concentration techniques are also available,
inc lud ing cryotrapping.
C. ORGANIC ANALYSIS INSTRUMENTATION
A variety of analytical instruments are available for
determining the concentration of the organics sampled from the
chamber, with GCs being the most commonly used. GCs have a wide
variety of columns available for separating organic compounds.
Capillary columns are generally preferred. Several detectors can
be used depending on the purpose of the test and the compounds of
11
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interest. Mass selective detectors (MSDs) are the most versatile
and can be used in the scan mode to identi t'y unknown compounds.
When us ed in the scan mode, an MSD has a sensitivity of about
10"9g. If the MSD is being used to analyze for known compounds,
it is operated in the selected ion mode where its sensitivity
increases to 10~12g. MSDs can be made even more sensitive by
negative ionization. Flame ionization detectors (FIDs) are also
widely used. They respond to a wide variety of organic compounds
and have a sensitivity of 10"11g. Electron capture detectors
(ECDs} are used for analyzing halogenated organics and have a
sensitivity of 10-13g. Some compounds are not easily measured
with GCs; for example, low molecular weight aldehydes require
other instrumentation (e.g., HPLC or wet chemical colorimetric).
D. STANDARDS GENERATION AND SYSTEM CALIBRATION
Calibration gas may be added to the test chamber or sampling
manifold from permeation ovens or gas cylinders. Calibration (or
tracer) gas is added through the test chamber in tests to
determine chamber mixing, check for leaks, or evaluate chamber
"sink" effects. Internal standards for quality control are added
at the head of the sampling system. The internal standard should
not be added to the chamber due to the potential for adsorption
on the material being tested. Quality control can also be
achieved by spiked samples,
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SECTION 4
EXPERIMENTAL DESIGN
A. TEST OBJECTIVES
The first step in designing an experiment for chamber tests
of indoor materials/products is to determine the test objectives.
For example, a builder or architect would be interested in
emissions from a variety of materials to be used under a given
set of conditions for a specific building. In this case, the
experiment would be designed to handle many materials with one
set of environmental conditions. A manufacturer might want to
know the emissions characteristics of a single product under both
normal and extreme conditions and would design a test to cover
the appropriate range of environmental variables, IAQ
researchers interested in the interactions among variables would
use a more complex design involving ranges of several variables.
B. CRITICAL PARAMETERS
A basic experimental design for small chamber tests should
include consideration of the effects of various parameters on the
emission characteristics of the materials to be tested. Five
variables are generally considered to be critical parameters:
temperature (T), humidity (H), air exchange rate (N), product
loading (L), and time (t):
Temperature
Temperature affects the vapor pressure, diffusion
coefficients (diffusivity), and desorption rates o f the organic
compounds in the materials/products and can have a major impact
on emission rates.
Humidity
Humidity has been shown to affect the emission rate of
formaldehyde from particleboard and may have similar effects for
other water soluble gases. Humidity can be expressed in relative
(% of saturation) or absolute (g water/g air) terms.
Air Exchange Rate
Air exchange rate (ACH or hr~1) is determined by the mass
flow rate of clean air to the chamber divided by the chamber
volume. The air exchange rate indicates the amount of dilution
and flushing that occurs in indoor environments and can have a
major impact on chamber concentrations.
Product Loading
Product loading is the ratio of the test specimen area to
the chamber volume. This variable allows product usage in the
13
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test chambers to correspond to normal use patterns for the same
product in "full scale" environments. Studies of formaldehyde
emissions have shown that the ratio of air exchange rate (N) to
product loading (L) is proportional to the emission rate. Thus,
N/L is often selected as a parameter in designing chamber
experiments. In some cases, the configuration of the source
makes product loading an inappropriate parameter. For example,
studies of sealants often employ elongated beads. In this case,
the configuration and length of the bead are appropriate
experimental design parameters.
Product Age
Age is a critical parameter, since most materials have
emission rates that vary with time. Fresh, wet solvent
containing products can have emission rates that vary several
orders of magnitude in a few hours; other materials such as
pressed wood products may have emission rates that take several
years to decay.
C. PRODUCT HISTORY
Information on the history of the material/product to be
tested is useful in designing the testing program. Details of
manufacture, production, or assembly may be useful in determining
compounds to be emitted. Information on product age, treatment
(e.g., coatings, cleaning), storage conditions (i.e., time,
temperature, humidity, ventilation), and handling/transportation
may provide additional insight. For example, older materials may
emit at a lower rate than new materials; materials stored at high
temperatures may also have lower emission rates when tested; and
storage or transportation with other materials may cause
adsorption of organics which will be emitted during the chamber
tests,
D. TEST MATRIX
For each material tested, a test matrix is developed to
allow the variables of interest to be investigated. As is normal
in experimental programs of this type, the desire to collect data
over an extensive parameter range is limited by cost and time
constraints. To maximize the information production within
available resources, a statistical consultant can be used to
provide guidance on appropriate experimental designs. Table 1 is
an example of a test matrix developed to evaluate the effect of
several variables on emission factors.
E. RECOMMENDED TEST CONDITIONS
For routine testing of indoor materials, the following test
conditions are recommended:
Temperature = 23°C;
Relative humidity = 45 - 50%;
Air exchange rate = 1.0 hr"1.
14
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TABLE 1. EXAMPLE TEST MATRIX
rest
Temp.
RH
Airflow
N
Surface Area
L
N/L
No.
(°c)
(%)
(I/min)
(hr- 1
) U2 )
(m2 / m3 )
(m/hr)
1A
23
50
1.4
0.5
0.035
0.2
2.5
IB
23
50
1.4
0.5
0.035
0.2
2.5
2A
23
50
2.8
1.0
0.035
0.2
5.0
2B
23
50
2.8
1.0
0.035
0.2
5.0
3A
23
50
5 . 5
2.0
0.035
0.2
10.0
3B
23
50
5.5
2.0
0.035
0.2
10.0
4A
23
50
2.8
1.0
0.070
0.4
2.5
4B
23
50
2.8
1.0
0.070
0.4
2.5
5A
35
50
1.4
0.5
0.035
0.2
2.5
5B
35
50
1.4
0.5
0.035
0.2
2.5
This test matrix covers five experimental conditions, each with
two replicates (A and B). The test matrix was designed to
evaluate the effect of specific parameters as follows:
a) Effect of Temperature (T) - Tests 1 and 5;
b) Effect of Air Exchange Rate (N) - Tests 1, 2, and 3;
c) Effect of Product Loading (L) - Tests 2 and 4;
d) Evaluation of Constant N/L - Tests 1 and 4.
The effect of humidity was not examined during this set of
experiments. The effect of age was investigated by collecting
multiple samples over the drying time of the product.
15
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SECTION 5
EXPERIMENTAL PROCEDURES
A. EMISSIONS COMPOSITION
A preliminary evaluation of the product/material is
performed to guide selection of appropriate test strategies and
analytical techniques. This evaluation is conducted to obtain
information on the specific compounds to be quantified. If only
a single compound is to be quantified, selection of the
appropriate sampling and analysis strategy is straightforward,
and no further screening is needed. When a more complete
characterization is desired, more information is required. An
initial evaluation of the composition of the emissions expected
from a source can be conducted by surveying available
information, including: a) reports or papers on previous studies
of the source, b) ingredients listed on the product label, c)
Material Safety Data Sheets (MSDS), and d) information obtained
from the manufacturer or appropriate trade organizations. Such
information is usually insufficient to identify the compounds of
interest, but it does provide some guidance in what compounds to
look f or. Another problem is that the compounds emitted from the
source may be formed during the use of the product or material
and will not be listed as ingredients. Therefore, further
analyses are required, and testing must be conducted to determine
the actual compounds being emitted. One technique involves
headspace analysis of the source emissions.
B. HEADSPACE ANALYSIS
The process of identifying the organic compounds present in
the "headspace" or air above the material is termed "headspace
analysis." Both static (i.e., closed container) and flow-through
headspace analyses are used. One method of conducting a
headspace analysis is to place a sample of material in a small
(e.g., 1 J or less) container lined with inert material. For
materials with high emission rates of organic compounds, the
quantity of volatile organic material in the sealed (i.e.,
static) headspace over a 0.1 to 0.25 g sample may be more than
enough to meet the detection limit requirements of an MSD
operated in the scan mode or other detectors. Low emission
materials, such as carpet, may require a different approach. A
purge gas {e.g., nitrogen) can be pulled over the material (i.e.,
flow-through) and collected on a sorbent trap. Sufficient
material and sampling time must be used to accumulate components
to a level adequate for detection by the MSD or other detector.
While headspace analyses are normally conducted at ambient
temperature (e.g., 23°C) and atmospheric pressure, it may be
necessary to increase the temperature (and thus the emissions) or
collect a larger sample if insufficient material is collected for
the detector being used.
16
-------
The headspace components are usually identified by gas
chromatography coupled with a mass selective detector (GC/MS)
operated in the scan mode, although other detectors can be used
if sufficient information is available on the retention times for
all compounds of interest for a given GC column, gas flow, and
temperature program. Use of several sampling and analytical
approaches may be necessary to characterize the spectrum of
compounds present in the headspace of a material. Techniques
applied depend upon such factors as polarity, solubility, and
boiling points of the compounds emitted. A variety of sorbent
materials are available (see Section 4.3). Once the sample is
collected, appropriate techniques (e.g., thermal desorption or
solvent extraction) are used to remove the organics from the
sorbent. Methods for injecting the sample into the GC will
depend on the sample phase (vapor or liquid) and on the specific
equipment available.
If different instruments are used for the headspace analysis
and chamber testing, the GC column, gas flow, and temperature
program used in both instruments should be the same so the
retention times for the compounds selected for quantification
will be known.
Based on the study objectives, some (or all) of the
compounds identified in the headspace analysis are selected for
measurement and quantification in subsequent chamber tests.
Criteria for selection of compounds may include: major peaks in
the gas chromatograph; known carcinogen, toxicant, or irritant;
and low odor threshold.
While the headspace analysis provides useful information on
the direct emissions from the material or product o f int ere st, it
does not ensure that all emissions will be identified. Sampling
and analysis techniques may be insufficient, or compounds not
found in the headspace may be emitted later due to being formed
in the drying process or by interactions with the substrate.
C. CHAMBER TESTING
Chamber testing requires a preparation phase as well as a
testing phase. The preparation stage begins with development of
the test plan that specifies environmental conditions for each
test (see Section 4 - Experimental Design), method of application
of the material, conditioning period, and methods of sample
collection and analysis. Development of the test plan is
followed by calibration of environmental control and measurement
systems, sample collection and concentration devices, and
analytical systems as specified in the QA Plan. At this stage
the information from the GC/MS headspace analysis is evaluated to
provide guidance in selection of analytical columns, detectors,
sample collection media, and an appropriate internal standard.
17
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Internal Standard
The internal standard, an organic compound added at a known
rate to the chamber exhaust, must meet several criteria;
a) it must be a readily available material (i.e., suitable
for use in a permeation tube or available in a gas
cylinder);
b) it must have a retention time on the analytical column
that does not overlap other compounds emitted by the
material;
c) it must be able to be quantitatively collected and
recovered from the sample collection media used during
the testing.
Also, it is desirable that the internal standard be inexpensive
and have low toxicity.
Chamber Preparation
Prior to actual testing, chambe Jf-1- 3^ €5 cleaned by scrubbing
the inner surfaces with an alkaline detergent followed by
thorough rinsing with tap water. Deionized water is used as a
final rinse. Chambers are then dried, placed in position in the
temperature controlled environment, and purged at test
conditions. Chamber background is monitored to ensure that
background contamination is within QA limits. At this point, the
chamber conditions are at test setpoints of flow and relative
humidity, all analytical systems have been calibrated, the QC
system has been developed, and the internal standard has been
selected. A chamber background sample is then taken to quantify
any contribution of organic compounds from the clean air system
and/or the empty chamber. In addition, any substrate materials,
such as wood, that will be used during the tests must be included
to account for actual background. Once all the preparatory steps
have been completed, testing of the selected material/product can
commence.
Specimen Preparation
The types of test specimens used in the chambers vary
according to the material or product being tested. Solid
materials are tested "as is," If emissions from edges may differ
from the normally exposed surface, the edges should be sealed.
For example, particleboard specimens can have their edges sealed
with sodium silicate to eliminate excessively high edge
emissions. "Wet" materials are applied to a solid substrate.
For example, a wood stain would be applied to a board, or a vinyl
floor wax, to floor tile. As noted above, the uncoated substrate
should be placed in the chamber during background tests to
determine the magnitude of its organic emissions. Also,
substrate edge effects should be eliminated by edge sealing. Wet
materials are applied to the substrate outside the chamber and
IB
-------
placed in the chamber shortly thereafter. The start of the test
(time =0) is set when the door to the chamber is closed. As
discussed in Section l.A. Scope, small chambers are not suitable
for evaluating the application phase of wet material use. Thus,
emissions from the earliest portion of the drying cycle (i.e.,
from application until placement in the chamber) will not be
measured. The time between application and the start of the test
should be less than 10 minutes; the time of application and the
test start time should both be recorded.
Specimen Conditioning
In some cases, emissions data are desired on later stages of
a material/product life cycle (e.g., several months after a
coating has been applied). In these cases, the specimen must be
conditioned prior to testing. Conditioning should occur under
the same environmental parameters (temperature, humidity, air
exchange rate, and product loading) as those used for chamber
tests. If this is not possible, the conditioning environmental
parameters should be well documented. Ideally, the sample should
be conditioned over its complete life cycle up to the time of
testing. If this is not possible, conditioning should be
conducted for a period of time sufficient to allow the emissions
to equilibrate to the test conditions (e.g., 1 to 2 weeks).
Specimen Contamination
Care should be taken in testing materials which have been
used or stored with other materials. In such cases, the material
of interest could have acted as a "sink" and adsorbed organics
from the other materials. Subsequent testing could provide
emissions data which represent the re-emission of the adsorbed
compounds rather than emissions from the original material.
D. SAMPLING AND ANALYSIS
Sampling
Coll ection of a representative sample of chamber effluent
requires the use of a sampling strategy that is appropriate to
the ranges of volatilities of the compounds present. The
information obtained from the GC/MS headspace analysis can be
used to select appropriate sample collection and concentration
media. As discussed above, the sampling method can range from
syringe/pump sampling to adsorption on various sorbent media.
Sampling techniques and sampling times must also be
appropriate to the concentrations of compounds in the chamber air
stream over time.
For constant emission rate sources, the sampling times are
not critical since the chamber concentration will reach a
constant equilibrium value. A minimum of three samples should be
taken after the time required to reach 99.9% of the equilibrium
value. Equation 3 can be rearranged and used to calculate this
19
-------
time, based on the air exchange rate, N (i.e., 0.999 = 1 - e~Nt;
e-Nt - 0.001; Nt = 6.9; t = 6.9/N). Thus, at an air exchange
rate (N) of 1 hr_1, it takes 6.9 hours for the chamber
concentration to reach 99.9% of its equilibrium value when a
constant emission source is placed in the chamber at time = 0;
for N = 0.5, it would take 13.8 hours, etc.
When testing wet materials such as gl ues, waxes, and
wood finishes, chamber concentrations may change by orders of
magnitude over a period of minutes, as shown in Figure 2.
Accurate description of chamber concentration with time may
require sampling very frequently or use of a continuous or semi-
continuous monitor. A combination of both techniques is the most
effective way to characterize rapidly changing emissions. The
concentration of individual compounds varies as the material
ages. In some cases, compounds not detected in the headspaee or
in the first few hours of testing may become the major emission
component. Therefore, a total hydrocarbon monitor can be
effective in tracking rapidly changing concentrations but may
provide an incomplete qualitative picture.
It is important, therefore, to monitor changes in the
emission profile as the material dries. The sampling strategy
should provide a means to collect approximately the same mass in
each sample. Thus, the sample volume is an important
consideration. When chamber concentrations are high, sample
volume must be kept low to avoid breakthrough in the collection
trap or overloading of the concentrator column of a purge and
trap device. Sample volumes less than 1 I can be drawn directly
by gastight syringes, then injected through a heated port to a
clean air stream flowing through sampling cartridges. Much
smaller samples (e.g., 1 cc) can be injected directly into the
GC. Larger volume samples are taken by pulling the chamber air
stream through sample cartridges as described above. Since the
flow through the cartridges is constant, increasing the sampling
time will increase the sample volume. It may be necessary to
conduct trial runs to develop a sampling strategy.
Extreme care must be employed in handling the sample
cartridges to avoid contamination. One technique is to
immediately place the cartridge in a sealed inert (e.g., Teflon)
bag that has been purged with nitrogen. Glass tubes with
airtight fittings can also be used.
Analysis
The analysis technique depends on the sampling strategy and
adsorbent media employed. Methods of introducing the sample to
the GC include direct injection, thermal desorption followed by
purge and trap concentration, and solvent extraction followed by
liquid injection.
20
-------
Time (hr)
Figure 2. Chamber concentration vs. time -- wood stain
-------
SECTION 6
DATA ANALYSIS
Data reduction and analysis is a mul ti step process.
Electronic spreadsheets can be used to reduce arid compile the
environmental and chemical analysis data with minimal data entry
steps. Chamber concentration data are used in various models to
produce estimates of material/product emission rates.
A. ENVIRONMENTAL DATA
Environmental data (i.e., temperature, relative humidity,
flow rate) can be recorded manually or automatically stored
(e.g., on floppy disks) by a PC based system. Summary
statistics that describe the environmental condition "setpoints"
and the actual values achieved (including variability) can be
computed, and a data summary sheet prepared (see Table 2).
TABLE 2. EXAMPLE ENVIRONMENTAL DATA SUMMARY
Test ID Number: PWF10
Material; Polyurethane Wood Finish
Sample Size: Weight = 2.39 g Area = 347 cm2
Chamber No.: 1 Chamber Volume: 0.166 m3
Material Loading (L): 0.21 mz/m3
Start Date Start Time End Date End Time
6/16/87 1105 6/19/87 1300
Chamber Environmental Parameters
Parameter Setpoint Average Standard Maximum/
Deviation Minimum
Temp (°C) 35.0 34.91 0.18 35.4/34.5
RH (%) 50.0 54.25 1.57 60.4/45.2
Flow (1/min) 2.8 2.72 0.01 2.86/2.67
22
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B. GAS CHROMATOGRAPHY DATA
GCs (including GC/MS) are interfaced to computing
integrators (or PC-based chromatographic data analysis systems)
for plotting of the chromatograms and computation of the areas of
peaks obtained. The data output is printed on paper as an analog
chromatogram plus a summary report. The data can also be stored
on magnetic media for future review or reprocessing.
The environmental information and the GC analysis results
are combined to give chamber concentrations for individual
compounds and total organics. In calculating concentrations, the
following factors are considered:
* Gas chromatographic system background (Includes
sorbent blank for sampling cartridge and purge and
trap concentrator);
* Chamber background (Determined from analysis of 10 to
20 I sample of chamber background, including
substrate);
* Elapsed time (Period of time in minutes from start of
test to midpoint of sampling period);
* Flow rate of the airstream carrying the internal
standard;
* Mass of internal standard added and mass observed
providing percent recovery;
* Mass observed for individual selected organic
compounds;
* An estimate of the total organics reported as a given
compound (e.g., toluene);
* Sampling duration and flow rate; and
* Test chamber flow rate.
Chamber concentrations for total organics and individual
compounds for each sample are calculated using a multi-step
process:
* Data may be normalized to the recovery of the
internal standard by multiplying the measured mass by
the reciprocal of percent recovery of the internal
standard. For example, if the percent recovery was
95%, the multiplier would be 1/0.95 = 1.053.
* Normalized mass is adjusted for system background and
chamber background.
23
-------
* The adjusted mass is divided by sample volume to
generate sampling manifold concentration data.
* Finally, chamber concentration is calculated by
multiplying the sampling manifold concentration data
by the ratio of flow out of the chamber plus standard
addition flow divided by flow out. This compensates
for dilution of the chamber effluent with the
internal standard flow.
Chamber concentration data coupled with sample size and
chamber air exchange rate are then used to estimate emission
factors) as discussed below.
C. EMISSION FACTOR CALCULATIONS
Emission factors for organics from indoor materials are
usually expressed in terms of mass/area-tiie. In some cases,
emission factors are reported as mass/mass-time or, in the case
of caulk beads, mass/length-1 i me, when a standard bead diameter
is used. (For convenience, the remainder of this section shall
use emission factor units of mg/m2-hr.) They are calculated for
individual organic compounds, as well as for total measured
organics. The method for calculating the emission factor depends
on the type of source being tested.
Constant Emission Rate
For materials with a relatively constant emission rate over
the test period, the chamber concentration will reach and
maintain a constant equilibrium value. For such materials the
calculation of the emission factor, when sinks are ignored, is
straightforward;
EF = C(Q/A) (4)
Where, EF = Emission factor, mg/m2-hr
C = Equilibrium chamber concentration, mg/m3
Q = Flow through chamber, m3/hr
A = Sample area, m2
An equivalent expression is also used;
EF = C(N/L) {5 )
Where, N = Chamber air exchange rate, hr-1;
L = Chamber loading, m2/m3
Note that N = Q/V, where ¥ = Chamber volume, m3.
24
-------
Decreasing Emission Rate
For sources that have emission rates that decrease over the
test period, a different procedure is required. The following
method applies to sources with initially high emission rates that
decrease with time. Most "wet" sources exhibit such behavior.
Models have been developed to analyze the results of the
chamber tests to provide emission rates (Tichenor, et al., 1988).
The simplest model (i.e., neglecting sink and vapor pressure
effects) assumes: a) the chambers are ideal continuous-stirred
tank reactors (CSTR), and b) the change in emission rate can be
approximated by a first order decay, as shown in Equation 6:
R = Roe"kt (6)
Where, Ro = Initial emission factor, mg/m2-hr
k = First order rate constant, hr"1
t = Time, hr
The mass balance for the chamber over a small time increment dt is:
Change in mass = Mass emitted - Mass leaving chamber
This can be expressed as:
VdC = ARoe-ktdt - QCdt (7)
Equation 7 can be rearranged:
dC/dt + (Q/V)C = (A/V)Ro e"k1 (8)
Equation 8 is a linear, non-homogeneous differential equation.
Given that C = 0 when t = 0, the solution to Equation 8 is:
C = AR0(e"k1 - e~Nt )/V(N - k) (9)
Using a non-linear regression curve fit routine, implemented
on a microcomputer, values of Ro and k can be obtained by fitting
the concentration vs. time data from the chambers to Equation 9,
In order to conduct such analyses, initial estimates of Ro and k
are required. A good initial estimate of k is:
k = Netk-N>taax (10)
Where, tmax is the time of maximum concentration (Cmax).
Note that Equation 10 often has two roots, one of which is
k = N. The other root should be selected. Graphical, trial and
error, or root trapping techniques can be used to estimate k from
Equation 10.
25
-------
Equation 10 is obtained by substituting C (Equation 9) into
Equation 8 and setting dC/dt = 0 at t = tmax. Once an estimate
of k is achieved from Equation 10, an initial estimate of Ro can
be obtained from Equation 9, Figure 3 illustrates the curve
fitting process for total organics data from a wood stain chamber
test; the solid line is the "best fit" of Equation 9, and the
data points are shown as diamonds. (Figure 3 shows only the
first 10 hr of data, but the fit was made over the total test
period.) Once Ro and k are determined, the value of R at any
time t can be calculated from Equation 6.
It is emphasized that the methods for determining emission
factors presented above are not applicable to sources that do not
exhibit either constant or simple exponential decay emissions
over time, and other emission models may be required. In
addition, the above calculation methods do not explicitly account
for several factors that may impact emission rates, including:
- the effect of chamber concentration on evaporative mass
transfer, as described by Equation 1;
- the effect of adsorption to and re-emission from "sinks";
and
- the effect of diffusion within the sample substrate.
Models are being developed, based on fundamental mass transfer
processes (see Section l.C), to include consideration of these
factors, but their use requires sophisticated statistical tools
and analysis experience that are not generally available. As
advances in source models are made, these "tools" will become
more available.
26
-------
1000
DO
-3
ro
cr*
E
c
.2
*D
•+J
C
0)
o
c:
o
a
N = 0.35 hr
N/L = 3.5
o = 20,900 mg/m2-hr
k = 1.5 hr"
Time (hr)
Figure 3.
Example chamber concentration curve for a wet source
{total organics from wood stain)
-------
SECTION 7
QUALITY ASSURANCE/QUALITY CONTROL
Small chamber testing of organic emissions from indoor
materials/products should be conducted within the framework of a
Quality Assurance Project Plan (QAPP). The QAPP should contain a
project description, data quality objectives/acceptance criteria,
QA/QC approaches/activities, and QA/QC audits.
Project Description
A brief description should include what materials are to be
tested; how the testing is to be conducted; and who is
responsible for various project activities. The project
experimental design (see Section 4) should contain the necessary
information for this portion of the QAPP.
Data Quality Objectives/Acceptance Criteria
This section of the QAPP defines the precision, accuracy,
and completeness desired for each parameter being measured.
Table 3 provides an example.
QA/QC Approaches/Activities
The types of QA/QC activities that might be specified in the
QAPP include establishment of a system of records/notebooks to
ensure proper operation of equipment and recording of data, such
as:
* Sample log to record receipt, storage, and disposition of
materials;
* GC standards preparation log to document preparation of
all organic compound standards;
* Permeation tube log to record weight loss data for all
permeation tubes;
* Calibration logs to contain environmental systems
calibration data;
* Instrument maintenance logs to document maintenance and
repairs of all equipment;
* Materials testing logs in which to record all pertinent
information for each test, including sample details,
sample ID number, and GC run ID number;
* Sorbent cartridge cleanup/desorption log detailing thermal
cleanup and QC validation of sorbent cartridges;
* Floppy disk storage log to document location and content
of electronically stored data; and
28
-------
TABLE 3. EXAMPLE DATA QUALITY OBJECTIVES/ACCEPTANCE CRITERIA
Parameter
Precision Accuracy Completeness
Temperature
Relative Humidity
Air Flow Rate
Substrate Area
Sample Weight*
Organic
Concentration
Emission Rate
±o.5°e
±5.0%
+ 1.0%
±1 .OX
+10.0%
+ 20% RSI)* *
+20% RSD
+ 0. 5° C
±10.0%
+ 2.0%
>90%
>90%
>90%
>90%
>90%
>90%
>90%
* For wet samples.
** RSD = Relative Standard Deviation = (s/ra)100%
Where, s = estimate of the standard deviation
in = mean
Note: Precision and accuracy are normally reported as
± 1 standard deviation unless otherwise noted.
Completeness refers to the percentage of planned
measurements actually conducted. For example, if 100
measurements were planned and 92 were conducted, the
completeness would be 92%.
29
-------
* Manuals governing operation of all equipment used by the
project,
QC activities are carried out by project staff in a routine,
consistent manner to provide necessary feedback in operation of
all measurement systems. Such activities might include:
* Routine maintenance and calibration of systems;
* Daily recording of GC calibration accuracy and precision
(i.e., control charting);
* Timely monitoring of percent recovery of the internal
standard that was added to all samples;
* Collection and analysis of duplicate samples;
* QC checking of organic collection sorbent tubes; and
* Periodic analysis of audit gases supplied by an
independent source.
QA/QC Audits
Finally, the QA/QC program should include periodic audits by
QA personnel to evaluate compliance with QAPP protocols.
30
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SECTION 8
REPORTING TEST RESULTS
The report of the test results should contain test
objectives, facilities and equipment, experimental design, sample
descriptions, experimental procedures, data analysis, results,
discussion and conclusions, and QA/QC.
Test Objectives
Describe the purpose of the test program.
Facilities and Equipment
Describe the test chambers, clean air system, environmental
measurement and control, sample collection (including adsorbents
if used), analytical instrumentation (e.g., GC, GC/MS), and
standards generation and calibration.
Experimental Design
Describe the test conditions, including temperature,
humidity, air exchange rate, and material loading; include a test
matrix if appropriate.
Sample Descriptions
Describe the sample(s) tested, including type of
material/product, size or amount of material tested, product
history, brand name (if appropriate), and sample selection
process (e.g., random). For wet samples, describe the sample
substrate. Also, provide information on sample conditioning,
including duration and environmental conditions.
Experimental Procedures
Describe the experimental procedures used during the
testing, including details of the sampling and analysis
techniques and references to published methods. For wet samples,
provide information on the application method.
Data Analysis
Show the methods, including appropriate models or equations,
used to analyze the chamber data to produce emission factors.
Results
Provide emission factors for each type of sample tested and
for each environmental condition evaluated. Emission factors can
be provided for individual organic compounds and/or total
organics. For sources with variable emission rates, provide
appropriate rate constants.
31
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Discussion and Conclusions
Discuss the relevance of the findings and provide
conclusions. For example, describe the effect of temperature
and/or air exchange rate on the emission factor,
Quality Assurance/Quality Control
Describe the Data Quality Objectives and discuss adherence
to the Acceptance Criteria. This should be done for both the
environmental variables and the chemical results. Provide the
results of duplicate and replicate sampling, and discuss the
outcome of any audits.
32
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REFERENCES
Adams, J., K. Menzies, and P. Levins. Selection and Evaluation
of Sorbent Resins for the Collection of Organic Compounds.
EPA-600/7-77-044, (NTIS No. PB 268-559), U.S. Environmental
Protection Agency, Research Triangle Park, NC, April 1977.
Gallant, R. F., J. W, King, P. L. Levins, and J. F. Piecewiez.
Characterization of Sorbent Resins for Use in Environmental
Sampling. EPA-600/7-78-054, (NTIS No. PB 284-347), U.S.
Environmental Protection Agency, Research Triangle Park, NC,
March 1978.
Harris, J. C., E. V. Miseo, and J. F. Piecewiez. Further
Characterization of Sorbents for Environmental Sampling -
II. EPA-600/7-82-052, (NTIS No. PB82-234667 ) , U.S.
Environmental Protection Agency, Research Triangle Park, NC,
July 1982.
Levine, I. N. Physical Chemistry. McGraw-Hill, New York, p.340,
1978.
Matthews, T. J., C. V. Thompson, D. L. Wilson, A. K. Hawthorne,
and D. T. Mage. Air Velocities Inside Domestic
Environments; An Important Parameter for Passive Monitoring.
In: Indoor Air'87 - Proceedings of the 4th International
Conference on Indoor Air Quality and Climate, Institute for
Water, Soil and Air Hygiene, West Berlin, Vol. 1, pp. 154-
158, August 1987.
Myers, G. E. Effect of Ventilation and Board Loading on
Formaldehyde Concentration: A Critical Review of the
Literature. Forest Products Journal, 34, p.59, 1984.
Piecewiez, J. F., J, C. Harris, and P. L. Levins, Further
Characterization of Sorbents for Environmental Sampling.
EPA-600/7-79-216, (NTIS No. PB 80-118763), U.S.
Environmental Protection Agency, Research Triangle Park, NC,
September 1979.
Tichenor, B. A., L. E. Sparks, and M. D. Jackson. Evaluation of
Perchloroethylene Emissions from Dry Cleaned Fabrics.
EPA-600/2-88-061, (NTIS No. PB89-118681), U.S. Environmental
Protection Agency, Research Triangle Park, NC, October 1988.
33
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BIBLIOGRAPHY
The scientific and technical literature contains numerous
references that report on the use of small environmental test
chambers for determining emissions of organic compounds from
indoor materials and products. The following references give
information on approaches to small chamber testing taken by
several investigators. These references are provided as
suggested reading for those who wish to supplement the
information contained in this guide. Further references are
cited in each of these publications.
Girman» J. R. , A. T. Hodgson, A. S. Newton, and A. W. Winkes.
Emissions of Volatile Organic Compounds from Adhesives with
Indoor Applications. Environment International, 12, p.312,
1984.
Matthews, T. G. Environmental Chamber Test Methodology for
Organic Vapors from Solid Emission Sources. Atmospheric
Environment, 21, p.321, 1987.
Molhave, L. Indoor Air Pollution Due to Organic Gases and
Vapours of Solvents in Building Materials. Environment
International, 8, p.117, 1982.
Tichenor, B. A., and M. A. Mason. Organic Emissions from
Consumer Products and Building Materials to the Indoor
Environment. Journal of the Air Pollution Control
Association, 38, p.264, 1988.
34
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