United States
                  Environmental Protection
                  Agency
Air and Energy Engineering     ,
Research Laboratory
Research Triangle Park NC 27711
                  Research and Development
EPA/600/S8-89/074  Nov. 1989
vvEPA         Project  Summary
                   Indoor Air  Sources: Using  Small
                   Environmental  Test Chambers  to
                   Characterize  Organic
                   Emissions from  Indoor
                   Materials and  Products
                   Bruce A. Tichenor
                   This report describes methods and
                  procedures for determining organic
                  emission  rates  from  indoor
                  materials/products using  small
                  environmental  test  chambers.  The
                  techniques presented are useful for
                  both routine product testing by
                  manufacturers   and  testing
                  laboratories  and for more  rigorous
                  evaluation by indoor air quality
                  researchers.
                   This Project Summary  was  devel-
                  oped by  EPA's  Air  and Energy
                  Engineering Research Laboratory, Re-
                  search Triangle Park, NC, to announce
                  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
                   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.  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.
  The use of small chambers to evaluate
organic emissions from indoor materials
has several objectives:

• developing techniques for screening
  products for organic emissions;
• determining the effect of environmental
  variables (i.e., temperature, humidity,
  air exchange) on emission rates;
• ranking products and product  types
  with respect to their emissions profiles
  (e.g., emission factors, specific organic
  compounds emitted);
• providing compound-specific  data on
  various organic sources to guide field
  studies and assist in evaluating IAQ in
  buildings;
• providing emissions data  for  the
  development and verification of models
  used to predict indoor concentrations of
  organic compounds; and
• developing   data  useful  to
  manufacturers  and builders  for
  assessing product  emissions and
  developing control options or improved
  products.

  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

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material. The concentrations observed in
the chambers should not  be used as a
substitute for concentrations expected in
full-scale indoor environments.

 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,  clean  air
generation system, monitoring and
control systems, sample  collection and
analysis  equipment, and standards
generation and calibration systems.
  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.
  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.  Electro-
polished 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.
  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 tech-
niques that have been used successfully.
   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 flow
required should be  calculated  before a
decision  is  reached on the  supply
system. The  required purity of the  air
must also be determined based on  the
type of samples to be evaluated.
  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,
rotometer) can be used. Temperature can
be  measured automatically  using
thermocouples or  thermistors;  manual
dial or stem thermometers  can  also be
used. Control of humidity depends on the
humidification system employed. If liquid
injection is  used,  water flow  is controlled
by the  pump setting. Control of humidity
by  saturated air  requires  temperature
control of the water and flow control of
the  saturated air stream. Humidity can be
measured using 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.

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 collection/
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 instru-
ments to analyze  organic emissions (e.g.,
gas chromatographs [GCs]).

Experimental  Design
  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.
  A  basic experimental design for small
chamber  tests  should   include
consideration of  the  effects of various
parameters on the emission  character-
istics of the materials to be tested. Five
variables are generally considered to be
critical  parameters:  temperature,
humidity,  air  exchange  rate,  product
loading, and time (or product age).
  For each material tested, a test  matrix
is  developed to  allow the  variables oi
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 anc
time  constraints. To  maximize  the
information production within  available
resources, a statistical consultant can b«
used to provide guidance on appropriate
experimental designs.

Experimental Procedures
  A  preliminary  evaluation  of  th(
product/material is performed  to  guidi
selection of appropriate test  strategie
and analytical techniques. This evaluatioi
is conducted to obtain information on th
specific compounds to be quantified.
only  a single  compound  is  to  b
quantified,  selection  of the appropriat
sampling  and analysis strategy i
straightforward, and no further  screenin
is  needed. When  a  more  complet
characterization  is  desired,  mor
information is required. The compositic
of  the emissions expected from a sourc
can  be evaluated  initially by  surveyin
available information,  including: a) repor
or  papers  on previous studies of tr
source, b)  ingredients  listed on th
product label, c)  Material Safety  Da
Sheets, and d) information obtained fro
the  manufacturer or  appropriate  trac
organizations. Such information is usual
insufficient to identify the compounds
interest,  but it  does  provide  son
guidance in what compounds to look f(
Another problem is that the  compoum
emitted from the source may be forrrv
during the use of the product or mater
and  will  not be listed  as ingredien
Therefore, further analyses are require
and  testing must  be  conducted
determine  the actual compounds bei

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emitted.  One  technique  involves
headspace  analysis of  the  source
emissions.

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.
Headspace  components are  usually
identified  by  gas  chromatography
coupled 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.
  While the headspace analysis provides
useful information on the direct emissions
from the material or product of interest, it
does not ensure that all emissions will be
identified.  Compounds not found in the
headspace may be emitted  later due to
being formed in the drying process or by
interactions with the substrate.

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, 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 Quality Assurance (QA)
Plan.  At this  stage the information from
the  GC/MS  headspace  analysis is
evaluated to  provide   guidance  in
selection  of analytical   columns  and
detectors,  sample collection  media and
an appropriate internal standard.
  Prior to actual testing,  chambers are
cleaned and  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 quality
control system has  been  developed, and
an internal standard has been selected. A
 ;hamber  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.
  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 the
excessively  high edge  emissions
previously reported. "Wet" materials are
applied to a solid substrate. For example,
a wood stain would be applied to a board;
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 edge effects
should be eliminated  by  edge  sealing.
Wet  materials  are  applied  to  the
substrate outside  the  chamber  and
placed in the chamber shortly thereafter.
The start of the  test (time  =  0) is set
when the door to the chamber is closed.
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 ten minutes; the
time of application and the test start  time
should both be recorded.
  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., one to  two
weeks).
  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.
  Collection 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 must  also  be
appropriate to  the  concentrations  of
compounds in the  chamber air  stream.
When  testing wet  materials such  as
glues,  waxes,  and  wood  finishes,
chamber concentrations may change by
orders  of magnitude over a  period  of
minutes. 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
headspace 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 of less than one
L  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 chamber air
stream through  sample  cartridges  as
described above. Since the flow through
                                                                             C r!nV/CDMAlCklT nniMTIfcl/

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       I
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.
  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.

Data Analysis
  Data  reduction  and  analysis is  a
multistep   process.   Electronic
spreadsheets can be used to reduce and
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.

Environmental and GC 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. GCs (including GC/MS)
are interfaced to computing integrators
(or  PC-based   chromatographic
dataanalysis  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. Chamber
    concentration data coupled with  sample
    size and chamber air exchange rate are
    then used to estimate emission factors.
    Emission Factors
      Emission factors for organics  from
    indoor materials are usually expressed in
    terms of mass/area-time. In some cases,
    emission  factors are  reported  as
    mass/mass-time, or, in the case of  caulk
    beads,  mass/length-time. 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.
      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)                      (1)

      where, EF = Emission factor, mg/m2-hr '

             C  = Equilibrium  chambe
                  concentration, mg/m3

             Q  = Flow  through  chamber
                  m3/hr

              A = Sample area, m2

        For  sources that  have decreasing
      emission rates over  the test period,  .
      different procedure  is  required.  Thi
      method (described in detail in the fu
      report) applies to  sources with initial!
      high emission rates  that decrease wit
      time.  Most  "wet"  sources exhibit  sue
      behavior. Equation 2 describes the rate c
      change in emission factor as a first ord«
      reaction:
R =
                                        (2
      where, R0 = Initial  emission  facto
                  mg/m2-hr
             k  = First  order  rate constant,
                  hr-1
             t  = Time, hr

        It is emphasized that these methods f(
      determining emission  factors  are  m
      applicable to sources that do not exhit
      either  constant or  simple exponent)
      decay  emissions  over  time, and othi
      emission models may be required.
        The EPA author, Bruce A. Tichenor (also the EPA Project Officer, see below), is with Air and Energy Engineering
         Research Laboratory, Research Triangle Park, NC 27711.
       The  complete  report, entitled "Indoor Air Sources: Using Small Environmental Test  Chambers to  Characterize
         Organic Emissions from Indoor Materials and Products," (Order No. PB 90-110 131/AS; Cost: $15.00, subject to
         change) will be available only from:
                 National Technical Information Service
                 5285 Port Royal Road
                 Springfield, VA22161
                 Telephone: 703-487-4650
       The EPA Project Officer can be contacted at:
                 Air and Energy Engineering Research Laboratory
                 U.S. Environmental Protection Agency
                 Research Triangle Park, NC 27711
      United States
      Environmental Protection
      Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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      EPA/600/S8-89/074
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