United States Environmental
Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
EPA/600/N-99/002 Spring/Summer 1999
&EFA
Inside I A Q
EPA's Indoor Air Quality Research Update
Engineering Solutions to
Indoor Air Quality Problems
Symposium
July 17-19, 2000
Raleigh, NC
(See Page 11 for Call for Papers)
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In This Issue
Page
Fungal Spores and the Influence of Humidity,
Velocity, and Amplification on Emission Rates 1
Evaluation of Potential P2 Approach
for Reducing Photocopier VOC Emissions 4
Testing of IAQ Simulation Software 5
Evaporative Emissions in Ventilated Rooms 6
Summaries of Recent Publications 8
Glossary 10
Call for Papers 11
FUNGAL SPORES AND THE INFLUENCE OF
HUMIDITY, VELOCITY, AND AMPLIFICATION ON
EMISSION RATES
Although a significant amount of work has been done to
elucidate the conditions under which fungi will grow on
material surfaces, little information is available that
quantitatively relates surface concentrations to airborne
concentration and ultimately exposure. This article discusses
the impact of relative humidity (RH), air velocity, and surface
growth on the emission rates of fungal spores from the surface
of contaminated material.
The two factors that were anticipated to have the most impact
on emissions were air velocity and RH. RH controls the
release of spores by some fungi. High RH is important for
those active release mechanisms that depend on the rupture of
turgid cells, while tissue desiccation in low RH is important to
another class of release mechanisms. The velocity of air
flowing over fungal colonies is known to be important to
dissemination both as a source of energy for liberation and to
enhance mass transport for humidity-driven processes.
In previous experiments, we found that fungal emissions were
influenced by complex interactions among RH, surface
growth, and material characteristics. RH has a tremendous
impact on the dissemination of both Penicillium and
Aspergillus spores. Under the high RH conditions where
growth occurred, there was little or no release of spores.
However, as the RH was lowered, spore release was
triggered. While the data are limited to these few cases, the
potential impact of the results on current control and
remediation practices was profound. Lowering uncontrolled
RH is almost always a recommended practice. The data in
this study point out that during remediation this could be the
wrong strategy and could lead to increased short-term
emissions.
(Continued on Page 2)
Inside IAQ, Spring/Summer 1999
Page 1
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The objectives of this study were to: 1) initiate experiments
relating surface load or concentration (for new growth) to the
emission of fungal spores, and 2) measure the impact of air
velocity at a variety of RHs. The experiments were conducted
in the Dynamic Microbial Test Chamber (DMTC). The
DMTC is a room-sized test facility designed to conduct
studies on the conditions and factors that influence
biocontaminant emissions and dissemination. It is a cube with
inside dimensions of 2.44 m, stainless steel walls and floor,
and an acrylic drop-in ceiling. Temperature (18-32°C) and
RH control (55 to 95%) are provided through an air handler
unit (AHU) with an air circulation rate between 1.4 and 4.8
mVmin.
The chamber was adapted to contain eight miniducts as shown
in Figure 1. The blower forces the conditioned DMTC air into
a High Efficiency Particulate Air (HEPA) filter, from which
the air for the eight miniducts is obtained. The channel design
was chosen for the miniducts to limit the total amount of air
required for a single test, allowing multiple tests to be run
simultaneously, and simulate flow conditions in a heating,
ventilating, and air-conditioning duct.
Three newly purchased common duct materials were studied:
two fiberglass duct liners (FDL-A and FDL-B) and one
fiberglass ductboard (FGD). In appearance, these duct liners
were very similar, with an uncoated surface intended to be
attached to a rigid duct material and a polymer coated surface
intended to be in contact with the moving air in the duct. FDL-
B contained a permanent (bound) antimicrobial in the coating
of the airstream surface. Penicillium chrysogenum and
Aspergillus were selected as the test organisms. P.
chrysogenum has been reported as one of the most frequently
isolated molds from the air, housedust, and surfaces of indoor
environments, and has been isolated from a number of air-
Inside IAQ is distributed twice a year and highlights indoor air
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Figure 1. Dynamic Microbial Test Chamber.
conditioning systems in environments where patients were
suffering from allergic disease. The materials were artificially
soiled and then inoculated in an aerosol deposition chamber.
The targeted amount of dust for deposition was
approximately 100 mg dust/100 cm2. This level has been
considered moderately soiled in previous experiments and
was selected to relate these data to previous experiments.
After artificial soiling and inoculation, the 30.5 x 91.4 cm (1
x 3 ft) pieces of test material were placed in the miniducts.
Temperature and RH throughout the miniducts were
maintained at 23.5 ° C and 94%, respectively. The air velocity
through the miniducts was 2.5 m/s (500 ft/min). At the start
of an emission rate determination, the chamber RH was
lowered from 94% to the test RH (i.e., 64%) by lowering the
RH setting on the AHU. Six isokinetic, 1-hour air samples
were collected using the Mattson-Garvin slit-to-agar sampler
for culturable bioaerosols. At the completion of each sixth
hour sample, chamber RH was returned to the maintenance
RH of 94%. No experiments were performed within 2 days
of any other to allow the surface of the materials to recover
from the decreased RH and to make certain the starting point
for all emission measurements was the same. Surface samples
were collected at weekly intervals, at least 1 day after the
bioaerosol sample was collected.
Colony forming units (CPUs) were counted shortly after visible
growth was first noted and again as moderate growth became
apparent. To calculate the emission rates, the CPUs on the
Mattson-Garvin plates were identified and enumerated, and the
Inside IAQ, Spring/Summer 1999
Page 2
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CFUs/min were determined. The value was adjusted for the total
flow rate and divided by the area of the emitting surface.
Figure 2 shows the impact of surface load during log-phase
growth on the emission rates of fungal spores from the surface
of the duct material using A. versicolor as the test organism.
The test material, FDL-B, was inoculated with two different
concentrations of A. versicolor. Emissions were measured at
64% RH. The columns represent surface growth and are
referenced to the left axis as Log10 CPU/10 cm2. The two
levels of inoculum used are denoted as lower and higher. The
lower inoculum was approximately 102 CPU/10 cm2, and the
higher inoculum was approximately 103 CPU/10 cm2. Error
bars are included for weeks 0 and 1 to show that no significant
difference was measured between the levels of surface growth
after the initial inoculation. The lines represent the spore
emissions results and are plotted on a log scale against the
right axis as CFU/m2/min. None of the differences between the
emission rates were significant except at week 3 (see error
bars). When comparing the surface and the emission data, it
is apparent that, for A. versicolor under these conditions,
surface load directly influences the emission rate. In other
words, as the surface concentration of organisms increased
during log-phase growth, the emission rate increased until a
stable population was reached, and then the emissions
appeared to remain essentially constant.
Table 1. Emission (CFU/m2/min) of P. chrysogenum spores
at four different airflow rates and RHs.
Figure 2. Surface growth vs. spore emissions for A.
versicolor at lower and higher inoculum levels.
Tables 1 and 2 present the first hour emission rate for P.
chrysogenum and A. versicolor, respectively. The surface
concentration was monitored to document that a stable
population of organisms had been established on the surfaces
of all the materials for at least 12 weeks.
MATERIA
L
FDL-B
FDL-A
FGD
RH
%
64
70
84
94
64
70
84
94
64
70
84
94
AIRFLOW, m/sec.
0.5
9
5; 1
1
2
610
27;7
0
26
13
8;1
1
17
1.0
13
28
1
5
155
30
25
7
20
6
0
0
1.5
409
228
59
124;127
465
229
234
145; 75
88
17
50
0
2.5
804; 2023; 1249
972; 1480
150
81
813; 2392; 1501
710; 1385
287
69
333; 854; 267
335; 162
12
47
Table 2. Emission (CFU/m2/min) of A. versicolor spores at
four different airflow rates and RHs.
MATERIAL
FDL-B
FDL-A
FGD
RH
%
64
70
84
94
64
70
84
94
64
70
84
94
AIRFLOW, m/sec.
0.5
1
0; 1
0
2
24
ii;
2
1
0
0
0;0
1
2
1.0
11
1
1
0
44
26
0
0
4
5
0
0
1.5
45
25
0
0;0
52
17
10
0;7
138
66
0
0;0
2.5
170; 100; 190
60; 20
0
11
43; 15
8; 14
3
20
567; 151; 543
242; 182
22
0
The first column lists the three different materials tested, and
the second column lists the four RHs at which the emissions
were measured. The final four columns show the emission
rates for the two test organisms at the four airflows used in
the study. In a number of cases (e.g., FDL-B, 64% RH at 2.5
m/s), multiple values, separated by a semi-colon, are
reported. These values are replicate measurements from
different experiments. In general, these data are in good
agreement.
As shown previously, the emission rates were inversely related
to the RH at airflows of 2.45 m/s. In other words, as the RH
decreased, the emission rate increased. The current experiment
generally confirms that relationship at the lower airflow rates.
Inside IAQ, Spring/Summer 1999
Page 3
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However, once the emission rate becomes too low, the natural
variability overwhelms our ability to measure a difference.
When the data from the different airflows are compared, the
emission rate is related to the flow rate across the
contaminated surface. As the flow rate increases, so do the
emission rates. This was seen at all four humidities included
in the study. Overall, the emission rates were notably lower
for the A. versicolor than the P. chrysogenum regardless of
RH or airflow.
While additional research will be required to relate these data
to exposure, the emission rates measured in these experiments
support data from our previous study, and modeling the
results shows that the emission rates produced room
concentrations consistent with field observations reported
from the literature.
In summary, the results show a complex interaction of factors.
For a limited data set, emission rates are inversely proportional
to RH, but directly related to airflow and surface loading. This
work was performed by Research Triangle Institute under
cooperative agreement number 000000. (EPA Contact: Marc
Menetrez, 919-541-7981, menetrez.marc @epa.gov)
EVALUATION OF POTENTIAL P2 APPROACH
FORREDUCING PHOTOCOPIER VOC EMISSIONS
This project is studying the potential for reducing the
emissions of volatile organic compounds (VOCs) from office
photocopy machines, through modifications to the raw
materials or the manufacturing process used in producing the
toners used in these machines.
In an earlier EPA report (EPA-600/R-98-080), concentrations
of selected VOCs were reported in the head space (static)
above samples from three lots of nominally identical toners,
raised to temperatures as high as 150 °C (the lower end of the
range at which the copier fusing mechanism typically
operates). According to the manufacturer, these three toner
lots nominally had the same chemical composition, and were
manufactured for use in the same copy machine. Yet the
samples from one of the lots consistently provided head-space
concentrations 50 to 80% lower than those from the other two
lots, for each of four specific hazardous organic compounds
that were measured. The four VOCs - styrene, ethylbenzene,
o-xylene, and m,p-xylene - are likely impurities resulting from
the polymer used in manufacturing the toners.
In the earlier report, it was noted that the toner lot producing
the lower head-space concentrations had been manufactured
using a continuous extrusion process, whereas the other two
had been manufactured at different facilities using a batch
process involving Banbury mixers. No information was
available regarding the purity of the specific polymer
feedstocks used in these manufacturing processes at different
sites.
A follow-on study is now underway to better define the extent
to which modifications to the toner manufacturing process
might offer pollution prevention (P2) opportunities for
reducing VOC emissions from photocopiers. This follow-on
effort initially involves head-space testing on toner samples,
as did the earlier effort discussed above, but addresses a
larger number of samples in an effort to systematically
separate out the effects of the different variables that could be
impacting the observed results. These variables include:
\) Manufacturing process. Three processes appear to be
commonly employed: continuous extrusion under vacuum;
continuous extrusion at atmospheric pressure; and batch
mixing (e.g., using a Banbury mixer).
2) Purity of the feedstock polymer.
3) Time at which the toner sample was collected during the
manufacturing run. At issue is the inherent variability in
toner characteristics over the course of a given run, with
a fixed process and feedstock.
4) Manufacturer and/or the machine for which the toner is
being produced (which would impact the nature of the
polymer and chemical composition of the toner). If the
manufacturing process or the feedstock purity is having a
major impact on VOC emissions, is this impact consistent
between vendors and toner types?
This study will address specific VOCs, in addition to the four
listed above, if other compounds are also found at high levels
in the head space.
If the results from this head space testing define an important
and consistent impact of one or more variables on head space
VOC levels, the study may be extended to include small
chamber testing of VOC emissions from copied paper
produced by a machine using both the lower- and the higher-
emitting toners. The objective would be to assess the extent
to which the lower-emitting toners would reduce VOC
emissions into the office space from copied paper after it has
left the photocopier room. (EPA Contact: Bruce Henschel,
919/541-4112, henschel.bruce@epa.gov)
Inside IAQ, Spring/Summer 1999
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TESTING OF IAQ SIMULATION SOFTWARE
An IAQ simulation software package, tentatively named the
Simulation Tool Kit for Indoor Air Quality and Exposure or
STKi, has recently started its beta test. STKi is a collection of
Microsoft Windows-based IAQ simulation programs with
similar user interfaces. It consists of a general-purpose
simulation program and a series of stand-alone, special-
purpose simulation programs.
The general purpose simulation program is designed to give the
user the flexibility to simulate a wide range of indoor air
pollution scenarios. It is capable of making multi-zone and multi-
pollutant simulations and allows gas-phase chemical reactions.
The special purpose simulation programs deal with mass
transfer models. In recent years, modeling of indoor sources
has gradually shifted from simple, statistical models to more
complex, fundamentally based models. While the latter
provide improved accuracy and validity, their usefulness has
been hindered by their increased complexity. Potential users
may want to avoid unfamiliar equations and the tedious
calculations behind them. The special-purpose simulation
programs in STKi help resolve this problem by shielding the
users from mathematical details and allowing them to
concentrate on lAQ-related issues.
An array of good IAQ simulation programs have been
developed and some can be easily obtained. STKi is not
designed to replace them. Instead, it complements and
supplements them. STKi is targeted mainly for advanced
users, those who are directly involved in IAQ exposure
estimation, risk assessment, or IAQ research. STKi is not an
expert system. It is the user's responsibility to determine what
model parameters to choose. Several emissions databases are
being developed in Europe and North America. Those
databases plus other sources can be useful tools in parameter
selection. STKi does not predict the air movement inside a
building, either. However, it does allow the user to input the
airflow data from existing air infiltration or computational
fluid dynamic models. The first public release of STKi is
expected in the winter of 1999 and will include the five
programs shown in Table 3.
Table 3. Programs included.
Carpet.EXE
GPS.EXE
PM.EXE
Spill.EXE
VBX.EXE
a model for VOC emissions from new
carpet
general-purpose simulation program
a model for indoor paniculate matter
models for indoor solvent spill
models for predicting VOC emissions from
solvent-based indoor coating materials based
on product formulation
The whole package will be developed in a cumulative
manner. More special-purpose programs will follow. Some
candidate programs currently under consideration are listed
in Table 4.
Table 4. Programs
proposed.
Chem. EXE
Latex.EXE
Pest.EXE
Water.EXE
WBC.EXE
model shell for indoor air chemistry
latex paint emission models
fugacity models for indoor application
of pesticides
models for VOC emissions from water
use (e.g., shower, washing machine,
and dish washer)
models for water-based cleaners (liquid
pool and wet film)
We welcome input from potential users, especially about their
needs and the programs they would like included. (EPA
Contact: Zhishi Guo, 919-541-0185, guo.zhishi@epa.gov)
Inside IAQ, Spring/Summer 1999
Page 5
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EVAPORATIVE EMISSIONS IN VENTILATED
ROOMS
VOCs are emitted from building materials, especially in many
new buildings. Emissions occur in a chainlike process:
diffusion inside the emitting material; crossing the surface-air
interface; transport across the mass transfer boundary layer;
and mixing into the bulk air. In any particular material, one of
these processes may be rate controlling. For freshly applied
liquid films, emissions are generally controlled by evaporation
from the surface and depend on local airflow parameters such
as temperature and velocity.
Experiments at different air velocity levels were performed in
a full-scale ventilated chamber to investigate the influence of
local airflow on evaporative emissions from a surface. The
experiments included velocity measurements of the flow over
the surface and measurements of chamber air concentrations.
The research was conducted in lEMB's large chamber by
Claus Topp of Aalborg University and was supported by the
Danish Technical Research Council.
Experiments were performed at EPA in a full-scale ventilated
chamber (4.0 x 2.8 x 2.6 m; 29 m3). Four slots provide
supply air to the chamber, one at the foot of each wall. Three
of the inlet slots direct the flow upward along the wall, and the
fourth inlet slot directs the flow along the floor. The return is
located at the center of the ceiling.
The experiments were performed at two different velocities
with temperature and RH kept fixed. In all experiments, the
air exchange rate was 1 air change per hour (ACH), and the
amount of recirculating air was changed to obtain different
velocity levels in the chamber. Two experiments were
performed at a total supply flow rate of 5 ACH (recirculation
rate of 4 h"1), and two experiments were performed at a total
supply flow rate 2 ACH (recirculation rate of 1 h"1).
In each of the experiments, a 1.48 m2 wood board was placed
at the center of the chamber floor. After conditioning, pure
decane (C10H22, equilibrium vapor pressure Cv= 12115 mg/m3
and molecular diffusion coefficient D = 0.0207 m2/h) was
applied to the top surface of the board. Smoke tests showed
that the flow over the wood board was parallel to the surface.
Velocity profiles were measured to obtain detailed knowledge
of the boundary layer flow over the wood board. The profiles
were measured with a hot-wire anemometer at the center of the
wood board and at 250 mm east, west, north, and south of the
center, respectively. The airflow in the chamber was from
east to west.
The concentration of decane in the chamber air was
determined by gas chromatography. Chamber air was pulled
through sorbent traps at a known flow rate using mass flow
controllers and a vacuum pump. Analytes were extracted
from the traps with carbon disulfide (CS2), and the con-
centration of decane in the extract was determined by
injecting a subsample of the extract onto the column of a gas
chromatograph equipped with a mass selective detector.
The velocity profiles over the wood board are shown in
Figures 3 and 4, for 2 and 5 ACH, respectively. As expected,
the maximum velocity decreases with distance from the inlet.
The velocities at the north and south locations, though, are
somewhat different indicating that the flow is not symmetric
around the board. The difference increases with the flow rate.
For 2 ACH, the maximum velocities occur approximately 3
cm above the surface and, for 5 ACH, they occur 2 cm above
the surface. As the flow rate is decreased, the maximum
velocities drop accordingly as shown in Table 5.
Table 5. Maximum velocities over the wood board.
ACH
2
5
Center
(m/s)
0.27
0.78
East
(m/s)
0.32
0.86
West
(m/s)
0.22
0.64
North
(m/s)
0.23
0.91
South
(m/s)
0.17
0.29
0.00 0.10 0.20 0.30 0.40
Velocity (m/s)
Figure 3. Velocity profiles over the
wood board for 2 ACH.
Inside IAQ, Spring/Summer 1999
Page 6
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150
Table 6. Mass transfer coefficients from non-linear
regression.
0
0.00 0.20 0.40 0.60 0.80 1.00
Velocity (mis)
Figure 4. Velocity profiles over the
wood board for 5 ACH.
Measurements of chamber concentrations overtime show that
chamber concentration reaches its maximum after approxi-
mately 0.5 h for 2 ACH and after 1 h for 5 ACH. Then the
concentration drops rapidly within 10 h. In the early stage of
the emission process, there is a significant difference between
concentrations from one velocity level to another but after
approximately 2 h the concentration levels are very similar. In
general, there is good agreement between the experimental
data and the model predictions using the mass transfer model
developed by IEMB, but the model seems to predict lower
peak concentrations. Concentrations from experiments with
the same total supply flow rate are very similar although there
is a 10 % difference between the peak concentrations for 2
ACH. For 5 ACH, there is a difference of 12 % in the amount
of VOC applied but the difference in concentration is not as
significant.
The emission rate can be conveniently expressed in terms of
a mass transfer coefficient as shown in Table 6.The standard
deviations from the regressions are within 12 %, which is
satisfactory. The mass transfer coefficients from experiments
with identical flow rates agree within 10 %.
Experiment
1
2
3
4
ke
(m/h)
10.29
11.07
4.01
3.64
Std.Dev.
(m/h)
0.84
1.29
0.19
0.21
Std. Dev
(%)
8.2
11.7
4.7
5.8
Results also show that emissions, expressed in terms of the
mass transfer coefficient, increase with velocity for fixed
temperature, RH, and air exchange rate. This emphasizes the
importance of testing materials at the correct velocity and
turbulence level in order to obtain the actual emission rate for
a given product.
As noted, the results agree with the IEMB model predictions
and show that, after reaching its maximum, the chamber
concentration drops rapidly within 10 h, which is consistent
with previous results obtained by IEMB. IEMB studied the
emission characteristics of a mixture of organic compounds,
including decane, and concluded that the first phase of the
emission process is controlled mainly by evaporation from the
surface. After that, the decay rate slows as diffusion
transport inside the material becomes the controlling
mechanism of the emission process.
In summary, two experiments were performed at each
velocity level, and the results are consistent, indicating a high
level of repeatability. It was found that the velocity level in
the boundary layer flow over the surface has a strong impact
on the mass transfer coefficient as the mass transfer
coefficient increases in proportion to the velocity. This
emphasizes the importance of testing materials at the correct
velocity and turbulence level to overcome scaling problems
when transferring results from a small-scale test chamber to
a full-scale ventilated room. (EPA Contact: Les Sparks, 919-
541-2458, sparks.les@epa.gov)
Inside IAQ, Spring/Summer 1999
Page 7
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SUMMARIES OF RECENT PUBLICA TIONS
Controlling Souces of Indoor Air
Pollution Through Pollution Preven-
tion - This paper overviews recent
research on the application of P2
techniques for improved IAQ: 1)
developing methods and tools that can
be used to evaluate emissions from
equipment or products; 2) developing
generic P2 solutions; 3) identifying
high-emitting raw materials or compon-
ents of products; and 4) evaluating low-
emitting materials. Test method guide-
lines for measuring emissions from
office equipment were developed and
then evaluated by testing four dry-
process copiers in one chamber and by
conducting a four-laboratory evaluation
using one of the copiers. For aerosol
consumer products, measurement
methods and models were developed
that can be used to belter understand
aerosol behavior so that more
efficacious and less toxic products can
be developed. A generic, innovative
spray nozzle for use with precharged
aerosol containers was developed and
evaluated. The new design allows for
the reformulation of selected aerosol
consumer products using water and air
in place of VOC solvents and hydro-
carbon propellants, respectively. High-
emitting components of common types
of finished engineered wood products
were identified by evaluating emissions
at each stage of the manufacturing
process. Three fiber panels and three
coatings were then identified as
potential low-emitting alternative
materials. Four types of printed circuit
board laminates were evaluated.
Glass/epoxy laminates and glass/lignin-
containing epoxy resin laminates
emitted fewer volatile compounds than
the two paper/phenolic resin-based
laminates. Source: Proceedings of the
ASHRAE Conference, "IAQ & Energy
'98. Using ASHRAE Standards 62 and
90.1 to Provide Acceptable Indoor Air
Quality and Energy Efficiency" (EPA
Contact: Kelly W. Leovic, 919-541-
7717, leovic.kelly@epa.gov)
Emissions of Odorous Aldehydes
from Alkyd Paint - Odorous aldehyde
emissions from a commonly used alkyd
paint were measured and characterized.
Initial formulation analysis indicated no
measurable aldehydes in the liquid
paint. However, small environmental
chamber tests showed that, for each
gram of the alkyd paint applied, more
than 2 mg of aldehydes (mainly
hexanal) were emitted during the curing
(drying) period. The emission profiles
of aldehydes were very different from
those of other VOCs such as alkanes
and aromatics. Since no measurable
aldehydes were found in the original
paint, it is suspected that the aldehydes
emitted were produced by autoxidation
of the unsaturated fatty acid esters in
the alkyd resins. It was found that the
hexanal emission rate can be simulated
by a mathematical model assuming that
the autoxidation process was controlled
by a consecutive first-order reaction
mechanism. The mathematical model
was used to predict the indoor air
hexanal concentrations for a typical
application of the alkyd paint tested.
The result indicated that the aldehyde
emissions can result in prolonged
(several days) exposure risk to
occupants. The occupant exposure to
hexanal emitted from alkyd paint also
could cause sensory irritation and other
health concerns. Atmospheric
Environment, 32,20,3581-3586,1998.
(EPA Contact: John Chang, 919-541-
3747, chang.john@epa.gov)
Estimation of the Rate of VOC
Emissions From Solvent-Based
Indoor Coating Materials Based on
Product Formulation - Two comp-
utational methods are proposed for
estimation of the emission rate of VOCs
from solvent-based indoor coating
materials based on the knowledge of
product formulation. The first method
utilizes two previously developed mass
transfer models with two key
parameters ~ the total vapor pressure
and the average molecular weight for
total volatile organic compounds
(TVOCs) ~ being estimated based on
the VOC contents in the product. The
second method is based on a simple,
first-order decay model with its
parameters being estimated from the
properties of both the source and the
environment. All the model parameters
can be readily obtained. Detailed
procedures for computing the key
parameters are described by using
examples. The predictive errors were
evaluated with small chamber data, and
the results were satisfactory. Thus, the
proposed methods provide a way to
predict the VOC emissions in the indoor
environment without having to conduct
costly chamber testing. The two
proposed methods work for both
TVOCs and individual VOCs. Pros
and cons for each method are discussed.
Source: Atmospheric Environment,
Vol. 33, No. 8, pp. 1205-1215, 1999.
(EPA Contact: Zhishi Guo, 919-541-
0185, guo.zhishi@epa.gov)
Inside IAQ, Spring/Summer 1999
PageS
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Exposure and Emission Evaluations
of Methyl Ethyl Ketoxime (MEKO) in
Alkyd Paints - Small environmental
chamber tests were conducted to
characterize the emissions of a toxic
chemical compound ~ methyl ethyl
ketoxime (MEKO) — from three
different alkyd paints. It was found that
MEKO emissions occurred almost
immediately after each alkyd paint was
applied to a pine board. Due to the fast
emission pattern, more than 90% of the
MEKO emitted was released within 10
hours after painting. The peak con-
centrations of MEKO in chamber air
correlated well with the MEKO content
in the paint. Material balance showed
that good recovery (more than 68%)
was achieved between the MEKO
applied with the paint and the MEKO
emitted. The chamber data were
simulated by a first order decay
emission model assuming that the
MEKO emissions were mostly gas-
phase mass transfer controlled. The
model was used to predict indoor
MEKO concentrations during and after
painting in a test house. It was found
that the predicted test house MEKO
concentrations during and after the
painting exceeded a suggested indoor
exposure limit of 0.1 mg/m3for all three
paints. The predicted MEKO
concentrations exceeded even the lower
limit of a suggested sensory irritation
range of 4 to 18 mg/m3 with two of the
three paints tested. The model was also
used to evaluate and demonstrate the
effectiveness of risk reduction options
including selection of lower MEKO
paints and higher ventilation during
painting. Source Indoor Air, 8, 295-
300, 1998. (EPA Contact: John Chang,
919-541-3747,chang.john@epa.gov)
Indoor Emissions from Conversion
Varnishes - Conversion varnishes are
two-component, acid-catalyzed
varnishes that are commonly used to
finish cabinets. They are valued for
their water- and stain-resistance, as
well as their appearance. They have
been found, however, to contribute to
indoor emissions of organic
compounds. For this project, three
commercially available conversion
varnish systems were selected. An EPA
Method 24 analysis was performed to
determine total volatile content, and a
sodium sulfite titration method was
used to determine uncombined (free)
formaldehyde content of the varnish
components. The resin component was
also analyzed by gas chromato-
graphy/mass spectroscopy (GC/MS)
(EPA Method 311 with an MS
detector) to identify individual organic
compounds. Dynamic small chamber
tests were then performed to identify
and quantify emissions following
application to coupons of typical
kitchen cabinet wood substrates, during
both curing and ageing. Because
conversion varnishes cure by chemical
reaction, the compounds emitted during
curing and ageing are not necessarily
the same as those in the formulation.
Results of small chamber tests showed
that the amount of formaldehyde
emitted from these coatings was 2.3 to
8.1 times the amount of free
formaldehyde applied in the coatings. A
long-term test showed a formaldehyde
emission rate of 0.17 mg/m2/h after
115 days. Source: Journal of the Air &
Waste Manage. Assoc. 48: 924-930,
1998. (EPA Contact: Elizabeth M.
Howard, 919-541-7915, howard.betsy
@epa.gov)
Inside IAQ, Spring/Summer 1999
Page 9
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GLOSSARY
ACH - Air Change per Hour
AHU - Air Handling Unit
CPU - Colony Forming Units
DMTC - Dynamic Microbial Test
Chamber
FDL - Fiberglass Duct Liner
FGD - Fiberglass Ductboard
GC/MS - Gas Chromatography/Mass Spectography
HEPA - High Efficiency Particulate Air
IAQ - Indoor Air Quality
IEMB - Indoor Environment Manage-
ment Branch
MEKO - Methyl Ethyl Ketoxime
NRMRL - National Risk Management
Research Laboratory
P2 - Pollution Prevention
RH - Relative Humidity
STKi - Simulation Tool Kit for IAQ
and Exposure
TVOC - Total Volatile Organic
Compound
VOC - Volatile Organic Compound
ERRATA
Please note the following typographical errors in the
Spring/Smmer '98 issue of Inside IAQ. Table 4, Page 7, the
first column, the entry "Formaldehyde" should be
"Formaldehyde*" and the entry "Formaldehyde*" should be
"Heptachlor"
Inside IAQ, Spring/Summer 1999
Page 10
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Call for Papers
Engineering Solutions to Indoor Air Quality Problems
Engineering Solutions to Indoor Air Quality Problems, an international symposium cosponsored
by the Air and Waste Management Association and EPA's National Risk Management Research
Laboratory, will be held July 17-19, 2000, in Raleigh, NC, at the Sheraton Capital Center.
Papers are invited on the following topics:
Managing the Risk of Indoor Air Pollution
Indoor Air Source Characterization
Methods
Indoor Air Source Management
Low Emitting/Low Impact Materials
Development (Pollution Prevention)
Biocontaminant Prevention and Control
Indoor Air Cleaning Methods
Asthma and Children's Health in the
Indoor Environment
! Ventilation
! HVAC Systems as Sources of Indoor
Air Pollution
! Air Duct Cleaning
! Particles and Particle Entry into the
Indoor Environment
! Indoor Air Quality Modeling
! Costs of Managing Indoor Air Quality
! Evaluation and Verification of IAQ
Alternatives
The symposium will consist of one general session so that participants will be able to attend all
sessions. A poster session, continuing education courses, and an exhibition of related products
and services are also planned.
Send abstracts of 200-300 words by January 10, 2000, to: Michael C. Osborne, U.S. EPA, MD-
54, Research Triangle Park, NC 27711; Telephone (919)-541 -4113; Fax (919)-541-2157; E-mail:
osborne.michael@epa.gov. Abstracts should include paper title and author(s) names, address(es),
and phone, fax number(s), and e-mail address.
Inside IAQ, Spring/Summer 1999
Page 11
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