United States Environmental
Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
EPA/600/N-98/002 Spring/Summer 1998
&EFA
Inside I A Q
EPA's Indoor Air Quality Research Update
In This Issue
Page
A Comparison of Indoor and Outdoor Concen-
trations of Hazardous Air Pollutants 1
Reducing Emissions from Engineered
Wood Products 8
Energy Costs of IAQ Control Through
Increased Ventilation in a Warm, Humid
Climate 12
Cost Analysis of Indoor Air Cleaners for
Organic Compounds: Activated Carbon
vs. Photocatalytic Oxidation 13
Summaries of Recent Publications 16
Back Issues of Inside IAQ Are Available ... 19
Glossary 20
PLEASE NOTE: We regret that the Fall/Winter
1997 issue was not published due to\
unanticipated delays
Inside IAQ is distributed twice a year and
highlights indoor air quality (IAQ) research
conducted by EPA's National Risk Management
Laboratory's (NRMRL) Indoor Environment
Management Branch (IEMB).
If you would like to be added to or removed from
the mailing list, please mail, fax, or e-mail your
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Inside IAQ, Art. Kelly Leovic
U.S. EPA -MD-54
Research Triangle Park, NC 27711
Fax: 919-541-2157
E-Mail: kleovic@engineer.aeerl.epa.gov
Also, check our home page on the Internet at:
htlp//www.epa.gov/docs/crb/iemb/iembhp.htm
A COMPARISON OF INDOOR AND OUTDOOR
CONCENTRA TIONS OF HAZARDOUS AIR POLL UTANTS
Many researchers who study IAQ believe that overall exposure to air
pollutants is greater indoors than outdoors. We note that most air
pollutants have many potential sources inside buildings, and therefore
indoor concentrations are likely higher, on average, than outdoor
concentrations. We then infer that indoor exposures (concentrations
breathed multiplied by duration of time breathed) must be
higher-perhaps much higher, given the high percentage of time most
people spend indoors. (In general, we have thought of "indoor" time as
time spent in buildings, in spaces that do not contain industrial,
manufacturing, or commercial processing operations. Time spent in
vehicles is counted by some authors as "indoors," and not counted by
others.)
The expectation that indoor concentrations of pollutants generally equal
or exceed outdoor concentrations (and that indoor exposures exceed
outdoor exposures) is based on three principal considerations.
! Concentrations of air pollutants are not reduced greatly when
outdoor air enters a building. Air that is brought into a building by
a mechanical ventilation system rarely has air cleaning devices for
pollutants other than particles, and these devices have very low
removal efficiencies for fine particles (with aerodynamic diameters
less than 10 \\m, and especially less than 2.5 pn). Air that enters
a building through infiltration is, in general, cleaned very little as it
penetrates openings in the building envelope. Literature on outdoor-
to-indoor reductions implies 0 to 50% reduction for most
substances. For reactive species like SOX, NOX, and ozone, the
reported reductions range from only 20% to a maximum of 80%
(Weschler et al, ES&T, 26: 179-184, 1980; Brauer et al., JAPCA,
4:171-181, 1991; Hoek et al., JAPC4 39:1348-1349, 1989; Liu et
al., Proc. Indoor Air; 93, 2:305-310, 1993; Andersen, Atm.
Environ., 6:275-278, 1972).
(continued on page 2)
Inside IAQ, Spring/Summer 1998
Page 1
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! People spend approximately 90% of their time indoors
(Analysis of the National Human Activity Pattern Survey
[NHAPS] Respondents from a Standpoint of Exposure
Assessment, EPA/600/R-96/074). The order-of-
magnitude greater time spent indoors than outdoors more
than offsets reductions in pollution concentrations that
may occur when air enters a building. Therefore, even if
there were no indoor sources, indoor exposures would be
greater than outdoor exposures.
! There are sources in buildings for most air pollutants.
The growing literature on measured emissions of gaseous
and particulate pollutants, supplemented by
compositional data on thousands of products used in
buildings, confirms that indoor sources can be significant
contributors to indoor concentrations and exposures.
Several field studies have shown higher indoor than outdoor
concentrations for many types of pollutants, especially for
volatile organic compounds (VOCs). A study of that literature
is underway in IEMB to determine the indoor/outdoor (I/O)
concentration and exposure ratios for hazardous air pollutants
(HAPs). This article summarizes the status of that study.
The starting point for the analysis was the list of 188 HAPs,
on the presumption that these substances are generally
considered health-hazardous by EPA and by U.S. society in
general. (Clean Air Act Amendments of 1990, Public Law
101-549, 104 Stat 2532-2534, November 15, 1990.)
In reviewing the literature on measured indoor and outdoor
concentrations, the list was narrowed to the 29 HAPs for
which two or more original references were available. The
three xylene isomers were grouped which resulted in a list of
27 substances. Eight of these substances are on the Agency's
list of HAPs "that present the greatest threat to public health
in the largest number of urban areas" and are being addressed
under the Urban Air Toxics Program in the Office of Air
Quality Planning and Standards (OAQPS) (See sections
112(c)(3) and 112(k) of Clean Air Act Amendments of 1990)
.Those eight substances are indicated by an asterisk in Tables
1-4.
The I/O concentration and exposure ratios determined in this
study are presented in Table 4. Tables 1-3 and the discussion
below provide the background information and the rationale
for the values presented in Table 4.
Using the eight references listed in the box below, reported I/O
concentrations and concentration ratios were compiled, and
typical concentrations and concentration ratios were selected.
Simple estimates of typical daily exposures (i.e., the product of
concentration and hours/day a person is exposed) were then
made for each of the 27 substances. Exposure estimates are
particularly important when comparing I/O situations because of
the order-of-magnitude difference in the amount of time the
typical person spends indoors versus outdoors.
(continued on page 3)
Sources of data for indoor and outdoor concentrations and concentration ratios (see Table 4 for citations).
Shah and Singh
1988
Samfield, 1992
Brown etal., 1994
Kelly etal, 1994
EPA Nonoccupational
Pesticide Exposure
Study (NOPES) 1990
Sheldon etal., 1992
Daisey etal.,
1994
Shields et al.,
1996
Literature survey
Outdoor concentrations
Literature survey
Indoor concentrations
Literature survey, Indoor concentrations
I/O ratios
Literature survey
Outdoor concentrations
Field study of pesticides
Indoor concentrations, Outdoor
concentrations, I/O ratios
Field study, Indoor concentrations,
Outdoor concentrations, I/O ratios
Field study, Indoor concentrations,
Outdoor concentrations, I/O ratios
Field study, Indoor concentrations,
Outdoor concentrations, I/O ratios
U.S. ambient air data through 1986
U.S. and foreign data through late 1980's data on
residences, office buildings, schools, other commercial
buildings
Comprehensive compilation and analysis of U.S. &
European literature, data on residences, office buildings,
schools, and other buildings
Comprehensive update of Shah and Singh, 1988
Approximately 350 samples from homes in Jacksonville,
FL and Chicopee-Springfield, MA
128 homes in Woodland, CA
12 office buildings in northern CA with 3 different types of
ventilation systems
70 telephone company buildings in 25 states and
Washington, D.C., 50 telecommunications centers, 11
office buildings,
9 data centers
Inside IAQ, Spring/Summer 1998
Page 2
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Concentration values from the literature that were extreme, or
from studies of locations or buildings with known high
concentrations, were avoided. A statistical meta-analysis was
not attempted, given the limited amount of data for most
substances. Median or geometric mean values were used
when possible, with the thought that arithmetic means tend to
be too biased by large values to represent typical conditions.
Ultimately, selection of the "typical" indoor or outdoor
concentration was subjective, based on the spread of the
summary data from the various references, the age of the data
in the references (more recent data were generally favored),
and the number of measurements represented by the
references (large data sets from a large number of sites or
studies were generally given more weight). Data from
buildings in the U.S. were given the greatest weight to reduce
possible confounding with data from countries where the
materials used in buildings and ventilation practices might be
different. However, a brief review of a Canadian study (Olson
etal.,Atm. Environ., 28(22): 3563-3569,1994)of757homes
in which 12 of the 27 HAPs were measured showed that only
two of the substances had means that were a factor of more
than 5 different from the typical indoor concentrations shown
in Table 4 (trichloroethylene was lower, paradichlorobenzene
was higher).
The concentration and exposure ratios in Table 4 are, where
possible, from studies where both indoor and outdoor
measurements were made: those values are shown in italics
and brackets in Table 4. For 15 of the 27 substances, such
data were not available, so straight arithmetic ratios of typical
indoor over typical outdoor were used. It is important to
understand that this compilation and analysis amounts to a
screening, or order-of-magnitude, assessment. Since most
studies in the literature have experimental design limitations
(e.g., in most studies the buildings were not statistically
selected), accurate estimates of exposures experienced by the
U.S. population cannot really be determined.
The analysis of data supports the hypothesis that indoor
exposures to most of these chemicals significantly exceed
outdoor exposures. The indoor concentrations of these 27
organic vapor HAPs are generally 1 to 5 times outdoor
concentrations, and indoor exposures are 10 to 50 times
outdoor exposures. Ratios for the pesticides in this group,
although less certain because of very limited data, appear to
be somewhat higher. This is an inevitable consequence of the
fact that the ratio of time spent indoors versus outdoors
(about 10) greatly offsets the fraction (generally 10 to 50%)
that outdoor pollutant concentrations are reduced when
outdoor air enters a typical building. In addition, there are
indoor sources for most of these substances, and these indoor
sources can be the major contributors to exposures.
Note that this analysis does not address health risk. Whether
any of the tabulated concentrations or exposures-indoor or
outdoor-pose health risks could only be estimated through
risk assessment.
This analysis is continuing and will consider new data as they
become available. An analysis of trends of some of these
substances, as reported over the past 15 years, is planned.
Relating them to sources is another challenging possibility.
(EPA Contact: W. Gene Tucker, 919-541-2746, e-mail,
tucker.gene@epamail.epa.gov)
Inside IAQ, Spring/Summer 1998
Page 3
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TABLE 1. Summary of Reported Indoor Concentrations of Selected HAPs ((Jg/m3)
HAP
Acetaldehyde*
Benzene*
Captan
Carbon
Tetrachloride*
Chlordane
Chloroform*
Cumene
2,4-D (salts, esters)
DDE
Dichlorvos
Ethylbenzene
Formaldehyde*
Heptachlor
Hexachlorobenzene
Hexane
Methoxychlor
Methyl Ethyl Ketone
Methylene Chloride
Naphthalene
Paradichlorobenzene
Propoxur
Radionuclides/Rn* *
Styrene*
Tetrachloroethylene*
Toluene
Trichloroethylene*
Xylenes (o+m+p)
Survey Articles or Reports
Shah and Singh Samfield (1992) Brown et al.
(1988) Avgof Avgof (1994)
Mean Median Medians Means WA, GMa
9.6
17 10 8 8.2 8
0.00185
25 0 <4 12
3.3 2.8
2.9 0.5 >8 8 10
5.1
0.0018
0.07
13 4.9 2.8 13.8 5
62 52 92
1.2 0.7
0.000126
5 33 12, 5
28 21 5.3 7 4,21
342 17
0.4 11
24 1.7 <2 31 8
0.093 0.34
1.2 1.8
21 5.1 <4 9.5 7
28 6.3 42 56 37
7.4 0.7 <1.4 5.9 47***
-12 -25 24
Individual Studies
NOPES(1990) Shields et
Average of Sheldon Daisey et al. al. (1996)
WghtdArith et al. (1992) (1994) Avgof
Means Median GM GMs
J'ville" Spr/Chicc
2.2 3.2
0.001 0.0001
0.5
0.26 0.12
<1.2
0.001 0.001
0.0003 0.0008
0.082 0.003
2.2 2
0.13 0.017
0.0007 0.0001 «0.8
2
0.0002 0
15 1.4
1 -0.1
0.3 0.022
1 1.7 -2
0.3 2
10 7
0.3 9.8
6 12 -7
"Typical"
Value
<10
5
O.001
<5
0.2
1
1
0.001
0.0005
0.05
5
50
0.1
0.0005
5
0.0001
10
10
1
1
0.1
2
2
5
20
5
15
* Urban Air Toxics substance
**Radionuclides/Rn in pCi/L
*** Measurements from buildings with IAQ complaints
a WA = Weighted Average GM = Geometric Mean
b Jacksonville, FL
c Springfield/Chicopee, MA
Notes for Table 1
o Values from Brown et al. (1994) were given the most weight, since they represent the most comprehensive, albeit
international, data set (Extracting U.S. data has not been attempted at this point.)
o Data on acetaldehyde are limited, and some investigators report measurement problems, hence the "less than" value.
o Chloroform data in the Brown survey are from only one office building, so greater weight was given to the more recent studies.
o Cumene and naphthalene data are very limited. Rather than deleting them, they were given a substantially lower value than
the reported means, which are relatively old data.
o The paradichlorobenzene value in Brown seemed high relative to other references, so more weight was given to more recent
data from Sheldon et al. (1992) and Shields et al. (1996).
Inside IAQ, Spring/Summer 1998
Page 4
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TABLE 2. Summary of Reported Outdoor Concentrations of Selected HAPs
HAP
Acetaldehyde*
Benzene*
Captan
Carbon Tetrachloride*
Chlordane
Chloroform*
Cumene
2,4-D (salts, esters)
DDE
Dichlorvos
Ethylbenzene
Formaldehyde*
Heptachlor
Hexachlorobenzene
Hexane
Methoxychlor
Methyl Ethyl Ketone
Methylene Chloride
Naphthalene
Paradichlorobenzene
Propoxur
Radionuclides/Rn**
Styrene*
Tetrachloroethy lene *
Toluene
Trichloroethy lene *
Xylenes (o+m+p)
Survey Articles
Kelly et al.
Shah and (1994)
Singh (1988) Median or
Median Range
2.4 2.7
5.4 5.1
ND
0.77 0.8
ND-0.63
0.29 0.2
0.2
ND-0.004
ND-0.13
ND-0.15
1.1
5.1 3.3
ND-0.63
ND-0.013
3.8
ND-0.007
ND
2.7 0.5
1.2 1.2
0.26 ND
0.001-0.2
(0.07-0.2)
0.6
2.4 1.7
7.2 8.6
0.86 0.4
10.7
Individual Studies
NOPES (1990)
Average of Sheldon et al. Shields et al.
Weighted Arith Means (1992) (1996)
J'villea Spr/Chicb Median GeoMean
1.1
ND ND
0.5
0.025 0.0025
0.00003 ND
ND ND
0.001 ND
1
0.015 0.0002
0.00007 ND «0.8
0.00003 ND
<2.8
0.3 0.05
0.045 0.0004
O.2
0.3 0.5
2.6
0.3
2.3 -3.4
"Typical"
Value
<3
5
O.0001
1
0.01
0.2
0.2
0.00003
O.002
0.001
1
4
0.002
0.0001
4
0.00003
<1
1
1
0.05
0.01
0.1
0.6
2
5
0.5
10
* Urban Air Toxics substance
**Radionuclides/Rn in pCi/L
ND = Not Detected
a Jacksonville, FL
b Springfield/Chicopee, MA
Notes for Table 2
o Kelly et al. (1994) is the primary reference for selection of typical values.
o Captan and DDE values based on detection limits reported in NOPES (1990).
o Hexachlorobenzene value arbitrarily selected from wide range of values reported.
o Methyl Ethyl Ketone detection limit not reported. Typical value of <1 is arbitrary, but I/O ratio in Table 3 is basis for
exposure ratio.
Inside IAQ, Spring/Summer 1998
Page 5
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TABLE 3. Summary of Reported Indoor/Outdoor Concentration Ratios of Selected HAPs ((Jg/m3)
HAP
Acetaldehyde*
Benzene*
Captan
Carbon Tetrachloride*
Chlordane
Chloroform*
Cumene
2,4-D (salts, esters)
DDE
Dichlorvos
Ethylbenzene
Formaldehyde*
Heptachlor
Hexachlorobenzene
Hexane
Methoxychlor
Methyl Ethyl Ketone
Methylene Chloride
Naphthalene
Paradichlorobenzene
Propoxur
Radionuclides/Rn* *
Styrene*
Tetrachloroethylene *
Toluene
Trichloroethylene *
Xylenes (o+m+p)
Shields et al.
Sheldon etal. Brown etal. Daiseyetal. (1996)
(1992) (1994) (1994) Avg. of Geo.
GeoMean GeoMean Range Means
5
2.1 3 0.25-4.2
1 2
5
6 0.48-2.5 2.1
9 0.26-18
4
6 1.0-45
4
6.9 5
4.1 10 0.69-13
1.8 5 2.8
6 0.63-5.2 3
6 1.7-84
2.4 6 0.5-3.5 ~2
"Typical" Ratio
5
2
2
5
3
10
4
10
4
5
5
3
5
5
2
* Urban Air Toxics substance
** Radionuclides in pCi/L
Note for Table 3
o All four references weighted about equally in selecting typical ratio.
Inside IAQ, Spring/Summer 1998
Page 6
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TABLE 4. Summary of Indoor and Outdoor Air Concentrations and Exposures for Selected HAPs
All ratios based on typical values from Tables 1-3; rounded to one significant figure.
HAP
Acetaldehyde*
Benzene*
Captan
Carbon Tetrachloride*
Chlordane
Chloroform*
Cumene
2,4-D (salts, esters)
DDE
Dichlorvos
Ethylbenzene
Formaldehyde
Heptachlor
Hexachlorobenzene
Hexane
Methoxychlor
Methyl Ethyl Ketone
Methylene Chloride
Naphthalene
Paradichlorobenzene
Propoxur
Radionuclides/Rn **
Styrene*
Tetrachloroethy lene *
Toluene
Trie hloroethy lene *
Xylenes (o+m+p)
Typical Concentration***
References
a,b,g
a,b,g,ef,h
c,a,b
a,b,g,h
c
a,b,e,g,h
a,b
a,c,b
c
c,b
a,d,b,g,e,f
a,b,g
c
c,b
a,b,e,f
c
a,b,e,g
a,g,e,f,h
a,b
a,d,b,e,h
c,a,b
a
a,b,d,f,h
a,d,b,e,e,g
a,c,b,d,e,f,
a,b,g,f,h
a,d,b,e,f
Indoor
(Hg/m3)
<10
5
0.001
<5
0.2
1
1
0.001
0.0005
0.05
5
50
0.1
0.0005
5
0.0001
10
10
1
1
0.1
2
2
5
20
5
15
Outdoor
(Hg/m3)
<3
5
ND@
1
0.01
0.2
0.2
0.00003
0.002
0.001
1
4
0.002
0.0001
4
0.00003
<1
1
1
O.05
0.01
0.1
0.6
2
5
0.5
10
I/O Ratio
[5]
[2]
10
[2]
20
[5]
5
30
>0.2
50
[3]
10
50
5
[10]
3
[4]
[10]
[4}
[5]
10
20
[5]
[3]
[5]
[5]
[2]
Typical Daily Exposure*
Indoor
(ug/m3 «h)
<216
108
0.02
<108
4.32
21.6
21.6
0.0216
0.0108
1.08
108
1080
2.16
0.0108
108
0.00216
216
216
21
21.6
2.16
43.2
43.2
108
432
108
324
Outdoor
(ug/m3 «h)
<7.2
12
0.0002
2.4
0.024
0.48
0.48
0.000072
0.005
0.0024
2.4
9.6
0.0048
0.00024
9.6
0.000072
<2.4
2.4
2.4
O.12
0.024
0.24
1.44
4.8
12
1.2
24
I/O Ratio
[50]
[20]
-100
[20]
200
[50]
50
300
>2
400
[30]
100
400
50
[90]
30
[40]
[90]
[40]
[50]
90
200
[50]
[30]
[50]
[50]
[20]
* Urban Air Toxics substance
**Radionuclides/Rn in pCi/L
*** Typical values from the literature for U.S. locations. I/O ratios based on typical concentrations [or reported ratios as indicated by
values in italics and brackets].
* Based on assumption that the typical person spends about 90% of the typical day indoors (in residential, non-industrial workplace,
educational, transportation, and commercial spaces such as retail) and 10% outdoors or industrial workplace [ref. i]. "Typical Daily
Exposure" is the product of typical concentration (ug/m3) times 21.6 hours for indoors, or times 2.4 for outdoors. [Ratios in italics and
brackets based on typical reported concentration ratios.]
® Substance undetected in hundreds of ambient air samples (ref. a); typical ambient value arbitrarily assumed to be 10% of indoor concentration.
References
a Kelly et al., ES&T, 28(8): 378A - 387A, 1994.
b Samfield, EPA-600-R-92-025 (NTIS PB92-158468),1992.
c NOPES Final Report, EPA/600/3-90/003 (NTIS PB90-152224), January 1990.
d Shields, Fleischer, and Weschler, Indoor Air, 6:2-17, 1996.
e Brown et al., Indoor Air, 4:123-134, 1994.
f Daisey eld.,Atm. Environ. 28(22):3557-3562, 1994.
g Shah and Singh, ES&T, 22(12): 1381-1388, 1988.
h Sheldon et al., "Indoor Pollutant Concentrations and Exposures", California Air Resources Board, contract A833-156, final report, January
1992.
i Klepeis, N. et al., Analysis of the National Human Activity Pattern Survey (NHAPS) Respondents from a Standpoint of Exposure
Assessment, EPA/600/R-96/074, 1996.
Inside IAQ, Spring/Summer 1998
Page 7
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REDUCING EMISSIONS FROM ENGINEERED
WOOD PRODUCTS
Engineered wood products include computer stations, desks,
entertainment units, book cases, kitchen and bathroom cabinets,
and counter tops. Particleboard (PB) and medium density
fiberboard (MDF) are the most common types of engineered
wood for constructing interior products. Hardboard (HB) is also
used. PB is made from finely ground wood particles of various
sizes, whereas MDF and FiB are made from wood fibers. In the
U.S., most interior-grade PB and MDF are bonded with urea-
formaldehyde (UF) resins; hardboard is bonded with phenol-
formaldehyde (PF) resins.
Engineered wood is typically finished prior to being assembled
into a product. Boards are printed or overlaid with materials to
give them a solid color, a wood grain pattern, or other decorative
look. Common types of overlays include vinyl, wood veneer,
and paper. A protective coating may also be applied to the paper
after it is overlaid to the board. Wood veneered boards are
usually coated with sealers and topcoats.
IEMB and Research Triangle Institute (RTF) recently completed
cooperative research to identify and evaluate pollution prevention
(P2) techniques to reduce indoor emissions from engineered
wood products. The research included three phases:
1) conducting emission tests on several types of finished
engineered wood;
2) identifying the highest emitting components of the samples
in phase 1; and
3) identifying and evaluating potential low-emitting
substitutes for the higher-emitting raw materials identified
in phase 2.
The results from the phase 1 and 2 research were highlighted in
the Spring/Summer 1996 issue of Inside IAQ (EPA/600/N-96-
002). In summary, emissions were screened from four types of
finished engineered wood: oak-veneered particleboard coated and
cured with a heat-curable acid-catalyzed alkyd-urea sealer and
topcoat (PBVST); oak-veneered hardboard coated and cured
with a stain, and a heat-curable acid-catalyzed alkyd-urea sealer
and topcoat (HBVSST); PB overlaid with vinyl; and PB overlaid
with melamine. The PBVST and HBVSST had substantially
higher initial emission factors of summed VOCs relative to the
other two. The PBVST and HBVSST also had higher long-term
emission factors of formaldehyde. In the phase 2 component
testing, the acid-catalyzed alkyd-urea coating and the PB were
identified as primary sources of VOCs and formaldehyde
emissions from the PBVST and HBVSST.
The remainder of this article covers the phase 3 research which
identified and evaluated potential low-emitting engineered
substrates and coatings.
Methods
Phase 3 consisted of two separate sets of emissions tests
designed to evaluate potential P2 options to reduce emissions
from finished engineered wood. One set of tests focused on
alternative engineered fiber panels, while the second focused on
alternative coatings.
Six types of engineered fiber panels were identified as
potentially low-emitting substitutes for constructing engineered
wood products (Table 5). Screening tests were conducted on the
six types of panels (samples A,B,C,D,E,N) and on PB
manufactured with wood fibers and UF resins (sample F). For
the fiber panel evaluation, three panels of each material were
collected from the last step in the manufacturing process, when
the panels were "ready for shipment." Several 0.006 m2
coupons were cut from the center of each panel. All coupons cut
from the same panel were placed in an airtight steel container
and transported to RTI. At RTI, the edges of the coupons were
sealed with sodium silicate, and the coupons were placed in
conditioning chambers, i.e., 3.8L steel cans operated at 50 %
RH, 23 ± 2 °C, and 1 air exchange per hour (ACH). After 26-
30 days of conditioning (representative of time elapsed before
installation), the coupons were placed in individual test chambers
and air samples collected.
Five alternative coatings systems were also identified and
evaluated as potentially low-emitting substitutes for heat-curable
acid-catalyzed alkyd-urea coatings (Table 6). Performance and
quantitative emissions tests were conducted on the five coatings
(coatings 2-6) and on the heat-curable acid-catalyzed alkyd-urea
coating (coating 1). The Electrotechnology Application Centerin
Bethlehem, Pennsylvania, coated and cured the unfinished PBV
and conducted the performance testing of the coatings.
Performance tests included: hardness; adhesion; fingernail mar
resistance; and chemical resistance to methyl ethyl ketone
(MEK), mustard, and 10 types of stains. Coatings were applied
to coupons using a drawdown bar which is a standard
laboratory technique for applying a uniform thickness of coating
to small substrates.
For the emissions testing of the coatings, each cured coupon was
placed in an airtight steel can and shipped to RTI. After 1
week, the coupons were removed from their containers and
placed in individual conditioning chambers (i.e., 3.8L steel cans
operated at 50 % RH, 23 ± 2 °C, and 1 ACH). The coupons
were conditioned for 27 days, at which time they were removed
from the conditioning chambers and placed in individual test
chambers. Chamber air samples were collected 1 day after each
coupon was placed in the test chamber.
Inside IAQ, Spring/Summer 1998
PageS
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TABLE 5. Selected Engineered Panels
Panel
Identification Fiber Source
Resin Source Interior Applications
A
B
C
D
E
F
N
Recycled newspaper
Wheat straw
Recycled corrugated cardboard
Lumber and plywood residuals
Lumber and plywood residuals
Lumber and plywood residuals
Lumber and plywood residuals
None
MDP
None
MDI
UF
UF
PF
floors, walls , subfloors, roof decking, filler board for furniture
PB applications such as furniture, cabinetry, shelving
furniture, store displays, countertops, shelving, etc.
MDF applications such as furniture, cabinetry, shelves
MDF applications such as furniture, cabinetry, shelves
PB applications such as furniture, cabinetry, shelves, floor
underlayment, stair treads
PB applications such as furniture, cabinetry, shelves, floor
underlayment, stair treads
1 MDI = Methylene diisocyanate
TABLE 6. Selected Coatings Systems
Chemistry
Carrier
Cure method
Coating 1
Acid-catalyzed
alkyd-urea
organic solvents
heat
Coating 2
Two-component
polyurethane
water
heat
Coating 3
Non-air-inhibited
unsaturated
polyester
water
UV light
Coating 4
Acrylate
none
UV light
Coating 5
Multi-functional
aery late-free
emulsion
water
heat + UV light
Coating 6
Polyurethane
dispersion
water
heat
Dynamic environmental test chambers, constructed of glass,
Teflon, and stainless steel, were used to measure emissions of the
engineered panels and the coated panels at RTI. The 0.012 m3
chambers were operated at 50% RH, 23 ± 2 °C, 1 ACH, and a
loading ratio of 1.0 m2/m3 [total surface area of the tested
material (0.012 m2) divided by the volume of the test chamber].
Target aldehydes and ketones were collected on dinitrophenyl-
hydrazine (DNPH)-coated silica gel cartridges and analyzed by
high pressure liquid chromatography with ultraviolet (UV)
detection. Other VOCs were collected on multisorbent cartridges
and analyzed by gas chromatography/mass spectrometry
(GC/MS). Emission factors for total VOCs (TVOC) were
estimated from the analysis of the multisorbent cartridges, and
did not include aldehydes and ketones collected on the DNPH
cartridges. Emission factors for "Summed VOCs" were
calculated by summing the individual emission factors of
aldehydes and ketones collected on the DNPH cartridges, and of
other VOCs collected on the multisorbent cartridges.
Results
Figure 1 presents emission factors of TVOCs and formaldehyde
for coupons of unfinished fiber panels. The TVOC and
formaldehyde data were statistically analyzed using a 95%
confidence interval to ascertain which samples differed with
respect to their emissions of TVOCs and formaldehyde. The
mean emission factors of TVOCs for test squares A, F, and N
were significantly higher than the mean emission factors of
TVOCs for test squares B through E. The mean emission
factors of formaldehyde for test squares E and F (the UF bonded
panels) were significantly higher than the mean emission factors
of formaldehyde for test squares A through D, and N.
For the coatings, the results of the performance tests are
discussed first followed by results of the emission testing.
Coating 1, the heat-curable acid-catalyzed alkyd-urea coatings
system, is the coating system that is currently used. Alternative
coatings systems 3,4, and 5 outperformed coating 1 in the MEK
test. Coatings 4 and 5 outperformed coating 1 in the mustard
test. For the stain tests, coatings 2, 4, 5, and 6 performed the
same as coating 1; coating 3 performed fairly well in the stain
tests except for its performance with grape juice and coffee. All
coatings performed equally well in the adhesion and fingernail
mar resistance tests.
Mean emission factors for the samples of veneered particleboard
(PBV) coated and cured with each of the six coatings systems
and for samples of uncoated PBV are presented in Table 7. The
data were statistically analyzed using a 95% confidence interval
to ascertain if emission factors of summed VOCs for test squares
of coated and cured PBV were significantly different than those
for test squares of uncoated PBV. The mean emission factors of
summed VOCs for test squares coated and cured with coatings
1, 3, and 6 were statistically higher than the mean emission
factor of summed VOCs for test squares of uncoated PBV,
indicating that these coatings systems are a significant source of
emissions from finished PBV. The mean emission factors of
summed VOCs for test squares coated and cured with coatings
2,4, and 5 were statistically lower than the mean emission factor
of summed VOCs for test squares of uncoated PBV, indicating
that these coatings systems are not a significant source of
emissions from finished PBV.
Inside IAQ, Spring/Summer 1998
Page 9
-------
The emission data were also statistically analyzed using a 95%
confidence interval to ascertain if emission factors of individual
and summed VOCs for test squares of PBV coated and cured
with coatings system 1 (i.e., the existing coatings system for
finishing PBVST in phases 1 and 2) were statistically different
than those for test squares of PBV coated and cured with the five
alternative coatings systems. The mean emission factor of
summed VOCs for test squares of PBV coated and cured with
coating 1 was significantly higher than the mean emission
factors of summed VOCs for test squares of PBV coated and
cured with coatings 2 through 6. The mean emission factors of
most organic solvents [such as butanol, C4- benzenes, 2-(2-
butoxyethoxy)ethanol] were significantly higher for test squares
of PBV coated and cured with coating 1 compared to test
squares with coatings 2 through 6.
A few caveats exist regarding the emissions tests. Certain
nonvolatile compounds that were listed in the material safety
data sheet (MSDS) for some of the coatings systems were not
analyzed in the emission tests; these included nitrocellulose,
p-toluene sulfonic acid, hexamethylene diisocyanate,
polyisocyanates, acrylate oligomers, and acrylic polymers.
These compounds were not analyzed because: 1) they were not
expected to be emitted into the air during testing (because of
their low volatility); 2) they were not expected to recover
efficiently from the emission test chambers, and 3) they were not
expected to be amenable to the analytical methods used for this
study. Certain volatile compounds that were listed in the
(MSDS) for some of the coatings systems were also not
analyzed in the emission tests; these included acrylate
monomers, N,N-dimethylethanolamine, and ammonia. Acrylate
monomers and N,N-dimethylethanolamine were not analyzed in
the emission tests because they were not amenable to the
analytical methods in the study and because they were not
expected to recover efficiently during the
chamber tests (due to their polar nature). Ammonia was not
tested for in the emission tests because it was not amenable to
the analytical methods in the study.
Summary
A variety of commercially available engineered fiber panels (i.e.,
those made with wheatstraw and MDI; wood and MDI; and
recycled corrugated cardboard) were found to have very low
emission factors of TVOC and formaldehyde (relative to UF-
bonded PB and MDF). These low-emitting engineered fiber
panels can be finished with veneer, vinyl, melamine, etc., and are
currently used to construct a wide variety of products for interior
applications. In future research, a broader study of the low-
emitting engineered fiber panels could be conducted to assess
manufacturing issues (e.g., cost) and performance.
A coatings study was conducted to evaluate performance and
emissions of potentially low-emitting substitutes for the acid-
catalyzed alkyd-urea coating. Within the scope of the tests
conducted, the heat-curable two-component polyurethane, the
UV-curable acrylate, and the UV-curable multifunctional
acrylate-free emulsion appear to be viable alternatives for the
heat-curable acid-catalyzed alkyd urea coating. In future
research, a broader study of the recommended coatings systems
could be conducted to determine how they perform in the
manufacturing environment, in terms of their ease of use, worker
safety, cleanup, manufacturing emissions, etc. The cost of the
coatings could be assessed in terms of equipment needs; e.g.,
stainless steel or plastic pipes for waterborne coatings, and UV
lights for UV coatings. Standard air sampling methods and
recovery techniques could also be developed for compounds that
could not be analyzed during the coatings evaluation. (EPA
Contact: Kelly Leovicc, 919-541-7717, E-mail:
kleovic@engineer.aeerl.epa.gov)
FIGURE 1 - Mean estimated emission factors of TVOC and formaldehyde
ti 600 T
500--
o
o 400
cS
fl
•i soo
200
100
1)
Formaldehyde
WOC
11.11. I.... I
Test squares are labeled by material letter
(A,B,C,D,E,F, or N) followed by panel
number and test square number.
A = panel made from recycled newspaper
B = panel made from wheatstraw and
MDI resin
C = panel made from recycled corrugated
cardboard
D = MDF MDI resin
E = MDF UF resin
F = particleboard with UF resin
N = particleboard with PF resin
< < < <
Inside IAQ, Spring/Summer 1998
Page 10
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TABLE 7. Mean Emission Factors for Uncoated and Coated Test Squares
Mean Emission Factors, ug/(m2«hr)
Uncoated test
Compounds squares of PBV
Formaldehyde
Acetaldehyde
Acetone
Propionaldehyde
2-Butanone
Butyraldehyde
Benzaldehyde
Valeraldehyde
m-Tolualdehyde
w-Hexanal
1-Pentanol
Limonene
Junipene
Terpenes
1-Butanol
Toluene
2-Methy 1- 1 -butanol
Butyl acetate
1,2-Propanediol
Ethylbenzene
m,p-Xylene
2-Heptanone
o-Xylene
Propylbenzene
Ethyl 3-ethoxypropionate
1 -Methy 1-2-pyrrolidone
2-(2-Butoxyethoxy)ethanol
Naphthalene
Hexyl acetate
Indan
C3-Benzenes
C4-Benzenes
Dipropylene glycol, methyl ether
Unknown 1
Unknown 2
TVOC"
Summed VOCsc
140
61
420
21
a
15
23
65
-
410
62
79
89
170
6
-
-
-
-
-
-
15
-
-
-
-
8
-
-
-
-
34
-
-
-
1000
1600
Coating 1
400
53
520
16
-
-
-
37
-
150
150
68
61
320
800
16
55
38
15
270
660
550
210
91
111
11
1700
24
400
13
1100
190
-
-
-
5200
7800
Test
Coating 2
20
41
490
15
-
-
-
26
-
120
16
54
24
220
-
-
-
-
-
-
-
8
-
-
-
-
43
-
-
-
-
25
-
-
-
610
1100
Squares Coated and Cured with
Coating 3 Coating 4 Coating 5
70
65
380
16
-
18
30
54
-
280
38
74
54
170
5
5
-
-
33
-
-
13
-
-
-
20
610
-
-
-
-
33
-
180
260
1700
2300
18
68
390
16
-
-
14
28
-
79
13
38
16
110
-
22
-
-
-
33
110
9
32
-
-
-
18
-
-
-
-
17
-
-
-
810
1000
19
41
430
12
-
-
18
19
-
93
14
37
13
100
8
-
-
-
-
-
-
7
-
-
-
5
6
-
-
-
-
16
24
-
-
540
900
Coating 6
33
68
510
17
-
12
23
57
-
350
49
83
67
120
7
6
-
-
-
-
-
22
-
-
-
2400
7
-
-
-
-
33
240
-
-
2800
4100
Coating 1 = heat-curable acid-catalyzed alkyd-urea
Coating 2 = heat-curable two-component polyurethane
Coating 3 = UV-curable non-air-inhibited unsaturated polyester
Coating 4 = UV-curable acrylate
Coating 5 = UV- and heat-curable multifunctional acrylate-free emulsion
Coating 6 = heat-curable polyurethane dispersion
a < 5 ug/(m2.hr)
b TVOC = total volatile organic compounds from TVOC analysis of multisorbent cartridges
'Summed VOCs are the sum of emission factors > 5 ug/(m2«hr), rounded to two significant figures
Inside IAQ, Spring/Summer 1998
Page 11
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ENERGY COSTS OF IAQ CONTROL THROUGH
INCREASED VENTILATION IN A WARM, HUMID
CLIMATE
Increasing the outdoor air (OA) ventilation rate is perhaps the
most common approach from improving IAQ. However, the
conditioning of this increased OA will increase energy
consumption and cost. The energy penalty associated with
increased OA will be greatest in hot, humid climates.
To assess the costs of increased ventilation in a hot, humid
climate, a series of computer runs has been completed using the
DOE-2.1E building energy model, simulating a small office in
Miami, FL. These simulations assessed the energy penalty, and
the impact on indoor RH, when the OA ventilation rate of the
office is increased from 5 to 20 cfm/person.
One objective of this analysis was to systematically assess how
each parameter associated with the building and with the
mechanical system impacts the energy penalty resulting from
increased OA. Another objective was to assess the cost and
effectiveness of off-hour thermostat set-up (vs. system shut-
down), and of humidity control (using overcooling with reheat),
as means for reducing the number of hours that the office space
is at an RH above 60% at the 20 cfm/person ventilation rate.
The small office modeled in this analysis was a 372 m2 (4,000
ft2) office in a single-story strip mall. Typical of such space, this
office is cooled by two packaged single-zone heating,
ventilating, and air-conditioning (HVAC) units.
With the baseline set of variables selected for this analysis, an
OA increase from 5 to 20 cfm/person is predicted to increase the
annual cost of energy consumed by the HVAC system by
12.9%. The analysis showed that the parameters offering the
greatest practical potential for energy savings are conversion to
very efficient lighting and equipment (1.5 W/ft2) and conversion
to very efficient cooling coils (electric input ratio = 0.284). If the
increase to 20 cfm/person were accompanied by either of these
conversions, the 12.9% HVAC energy penalty for the increased
OA rate would be eliminated; the modified system at 20
cfm/person would have a 2 to 5% lower annual HVAC energy
cost than the baseline system at 5 cfm/person.
Other parameters offering significant practical potential for
energy savings are: conversion from packaged single-zone units
to a variable air volume system; conversion to cold-air
distribution (minimum supply air temperature = 42 °F); or
improvements in the glazing or in the roof resistance to heat
transfer. If the OA increase were accompanied by any one of
these modifications, the 12.9% penalty would be reduced to
between 2 and 7% (the modified system at 20 cfm/person
compared against the baseline at 5 cfm/person).
According to the DOE-2.1E model, the increase in ventilation
rate could be achieved with an 85% reduction in the number of
occupied hours above 60% RH, compared to the baseline system
at 5 cfm/person — with only a $19/year increase in energy cost —
if the economizer were eliminated. That is, most of the elevated-
RH hours in the baseline case were predicted to be the result of
economizer operation. If the control system were modified so
that it controlled the humidity as well as the temperature in the
office space, all of the elevated-RH occupied hours would be
eliminated, at an energy cost of $90/year.
Neither economizer elimination nor humidity control would
address unoccupied periods, when most of the elevated-RH
hours occur. Building operators concerned about biological
growth at elevated RH should consider operation of the cooling
system during unoccupied hours, perhaps with the thermostat set
up, rather than system shut-down off-hours. Off-hour set-up
from 75 to 81 °F would add only $10/year to energy costs, and
would provide some modest reduction in unoccupied elevated-
RH hours. Set-up to 79 °F would provide a greater reduction, at
an energy cost of $38/year.
DOE-2.1E underestimates the number of elevated-RH hours
because it does not address the moisture capacitance of building
materials and furnishings, or re-evaporation off the cooling coils
when they cycle off with the air handler operating. As a result,
the performance of the RH reduction steps above may be over-
estimated, or the costs of the steps underestimated. (EPA
Contact: Bruce Henschel, 919-541-4112,
bhenschel@engineer.aeerl. epa.gov)
Inside IAQ, Spring/Summer 1998
Page 12
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COST ANALYSIS OFINDOORAIR CLEANERS FOR
ORGANIC COMPOUNDS: ACTIVATED CARBON
VS. PHOTOCATALYTIC OXIDATION
In the Fall/Winter 1996 edition of Inside IAQ (EPA-600/N-97-
001), an initial cost analysis was presented comparing granular
activated carbon (GAC) versus photocatalytic oxidation (PCO)
as means for removing VOCs from indoor air. Since the time of
that earlier analysis, a more rigorous cost comparison has been
completed.
For this new analysis, it was assumed that an office having a
steady-state VOC concentration of 2 mg/m3 and an air
recirculation rate of 7 air changes per hour, is to be reduced to
a steady-state concentration of 0.3 mg/m3 (about 0.1 ppmv).
Mass balance indicates that the air cleaner would require a per-
pass removal efficiency of 82%.
Design of the GAC Air Cleaner
At the steady-state inlet concentration of 0.1 ppmv and 50% RH,
the GAC was assumed to have the capacity to adsorb 2.0 g
VOC per 100 g carbon before breakthrough becomes
unacceptable. This is the measured capacity of GAC for hexane
at those conditions. Carbon's capacity for hexane is at about the
median for organic compounds having four or more atoms
(exclusive of hydrogen). Lighter organics could have capacities
that are one or more orders of magnitude poorer.
The GAC unit costed here is illustrated in Figure 2. This config-
uration-involving a series of 2.5-cm-thick GAC panels in a V-
bank arrangement-is representative of many units offered
commercially for IAQ applications. With the assumed sorption
capacity, the carbon would have to be replaced every 3.7
months.
Design of the PCO Reactor
The PCO reactor was assumed to have a differential oxidation
rate of 0.11 (jmol/hr per cm2 of illuminated TiO2 at an inlet
concentration of 1 ppmv and an UV illumination intensity of 1
mW/cm2. This rate is based on limited literature data available
at such low concentrations. The rate is assumed to decrease with
concentration below 1 ppmv according to first-order kinetics,
consistent with theory and data. To achieve this rate, the
required UV intensity incident on the catalyst is assumed to be 1
mW/cm2, consistent with published data.
Since design information for PCO reactors on the market is
highly proprietary, a model PCO reactor was designed for the
purposes of this analysis. Since this model reactor contains a
significant catalyst surface area per unit reactor volume, it
should illustrate the major cost centers associated with PCO
reactors, even though it undoubtedly differs from the proprietary
commercial units.
The model PCO reactor is shown in Figure 3. It assumes the
same V-bank panel bed configuration as for the GAC unit, but
with the carbon panels replaced by panels of ceramic foam
substrate coated with catalyst. For the oxidation rate and
illumination assumptions cited above, there would need to be six
banks of panels to achieve the desired 82% per-pass efficiency,
and the total input power would be 9,OOOW to the UV bulbs plus
an additional 900W to the ballasts.
The installed costs of these reactors (expressed as cost per m3/s
reactor capacity) and the operating costs (in cost per year per
m3/s) are presented in Table 8. These costs are based largely on
vendor quotes and on Means Mechanical Cost Data (e.g., for
labor rates). The DOE-2 building energy model was used to
compute the increases in energy consumption and cooling
capacity requirements.
Conclusions
Analysis of these results leads to the following conclusions.
1. With the assumptions used in this analysis, the PCO reactor
has an installed cost over 10 times greater, and an annual cost
almost 7 times greater, than those of the GAC adsorber.
2. Changes in the assumptions for the GAC unit, to include
VOCs not effectively sorbed on carbon, can increase GAC
installed and annual costs to levels comparable to (or higher
than) the PCO unit.
3. However, even with the most optimistic adjustments to the
assumptions for the PCO unit, it does not appear possible to
reduce the PCO installed and annual costs by a factor greater
than 2 to 4. Even with reductions by a factor of 2 to 4, PCO
would still be sufficiently expensive such that it would not likely
be widely accepted for general indoor air applications.
4. The high PCO costs result from the large amounts of catalyst
surface area and of UV power that are required for the
photocatalysts reported in the literature. The high surface area
and power requirements are dictated by the literature data, and
cannot be reduced by innovations in reactor or lighting
configurations.
5. Only a significantly improved catalyst having a greater
quantum efficiency - capable of providing faster oxidation rates
with less catalyst area and less illumination - can reduce PCO
costs by a factor greater than 2 to 4.
(EPA Contact: Bruce Henschel, 919-541-4112, bhenschel@
engineer.aeerl .epa.gov)
Inside IAQ, Spring/Summer 1998
Page 13
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FIGURE 2. GAC VOC air cleaner (side view).
PARTICULATE FILTER
to protect fan and coils
(unit illustrated is 10 cm thick
pleated filter, ASHRAE 30)
GAC FILTER AND
FILTER HOUSING
(0.6x0.6x0.3m)
/
RETURN DUCTING
(0.6 x 0.6 m cross section)
Return air from
occupied space
\
u . _ .
12 panels containing granular
charcoal, 2.5 cm thick
To HVAC air handler and
cooling/heating coils
Elements showing in dashed lines: Equpment already present as part of basic HVAC system.
Elements shown in solid lines: Equipment added as part of VOC air cleaner.
Note: This illustration shows a single 1 m3/s system. Higher capacities are achieved by combining
multiple such units into a bank of filters.
FIGURE 3. Model PCO VOC air cleaner (side view).
One medium-pressure mercury bulb operated at:
750 W 1.500 W
PARTICULATE
FILTER
to protect fan
PCO REACTION UNIT
AND HOUSING (1 of 6)
(0.6 x 0.6 x 0.3 m)
12 panels of substrate (each 0.6 x 0.3 m)
coated with TiO2 photocatalyst:
Ceramic foam (4 pores/cm), 2 cm thick
PARTICULATE FILTER
to remove TiO2 particles
(illustrated is a pleated
filter, ASHRAE 30)
Housing for ballast
and wiring
Total reactor length = 3.4 m
Total input power to UV bulbs = 9,000 W
Elements shown in solid lines: Equipment added as part of the VOC air cleaner.
Note: This illustration shows a single 1 m3/s system.
Inside IAQ, Spring/Summer 1998
Page 14
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TABLE 8 -Summary Cost Comparison of GAC vs. PCO for VOC Control in Indoor Air
COST ($ per m3 / s or $ /yr per m3 /s)
COST ITEM ACTIVATED CARBON PHOTOCATALYTIC
Equipment and Installation Costs ($ per m3 / s)
Reactor (excluding carbon/catalyst) 850 8,090
Initial carbon/catalyst charge 470 6,480
Enlarged central air handler (to provide increased static 60 20
pressure)
Increased cooling coil capacity (to remove air handler, bulb heat) 150 1,720
TOTAL INCREMENTAL INSTALLED COSTS 1,530 16,310
Total Annual Costs ($ per yr / m3 / s)
Operating
Electricity cost (for increased HVAC cooling load, fan static
pressure, power for UV bulbs) 100 4,440
Maintenance
Replacement of carbon 1,360 —
Regeneration of catalyst — 1,510
Disposal of spent carbon/catalyst 20 ~ 0
Replacement of UV bulbs — 2,370
Replacement of final filter — 20
Capital Charges
Equipment depreciation (10 year straight) 150 980
Catalyst depreciation (5 year straight) — 1,500
Insurance and real estate taxes 30 330
Interest on capital (installed cost) 60 650
TOTAL INCREMENTAL ANNUAL COST 1,720 11,800
Inside IAQ, Spring/Summer 1998 Page 15
-------
SUMMARIES OF RECENT PUBLICATIONS
This section provides summaries of recent
publications on EPA's indoor air
research. The source of the publication is
listed after each summary. Publications
with NTIS numbers are available
(prepaid) from the National Technical
Information Service (NTIS) at 5285 Port
Royal Road, Springfield, VA 22161,703-
487-4650, or 800-553-6847.
Development of an Innovative Spray
Dispenser to Reduce Indoor Air
Emissions from Aerosol Consumer
Products - The operating principles and
performance of a new type of spray
nozzle are presented in this report. This
nozzle, termed a "ligament-controlled
effervescent atomizer," was developed
to allow consumer product
manufacturers to replace VOC solvents
with water and hydrocarbon propellants
with air, while meeting the following
restrictions: that the spray mean drop
size (reported here as Sauter mean
diameter, or SMD) remain below 70
(jm, that the atomizing air consumption
be less than 0.009, and that atomizer
performance be uncompromised by the
increase in surface tension or by
changes in viscosity. The current
atomizer differs from previous
effervescent designs through inclusion of
a porous disc located immediately
upstream of the nozzle exit orifice. The
disc controls the diameter of ligaments
formed at the injector exit plane.
Source: EPA Report (EPA Contact:
Kelly W. Leovic, 919-541-7717,
kleovic@ engineer.aeerl. epa.gov)
Energy Costs of IAQ Control
Through Increased Ventilation in a
Small Office in a Warm, Humid
Climate - A series of computer runs
were done using the DOE-2.1E
building energy model, simulating a
small (4,000 ft2) strip mall office
cooled by two packaged single-zone
systems, in a hot, humid climate
(Miami, FL). These simulations
assessed the energy penalty, and the
impact on indoor RH, when the OA
ventilation rate of the office is
increased from 5 to 20 cfm/person.
With the baseline set of variables
selected for this analysis, an OA
increase from 5 to 20 cfm/person is
predicted to increase the annual cost of
energy consumed by the HVAC
system by 12.9%. The analysis showed
that the parameters offering the greatest
practical potential for energy savings
are conversion to very efficient lighting
and equipment (1.5 W/ft2) and
conversion to very efficient cooling
coils (electric input ratio = 0.284). If
the increase to 20 cfm/person were
accompanied by either of these
conversions, the 12.9% HVAC energy
penalty for the increased OA rate
would be eliminated; the modified
system at 20 cfm/person would have a
lower annual HVAC energy cost than
the baseline system at 5 cfm/person.
Other parameters offering significant
practical potential for energy savings
are: conversion to cold-air distribution
(minimum supply air temperature = 42
°F); or improvements in the glazing or
in the roof resistance to heat transfer.
According to the DOE-2 model, the
increase in ventilation rate could be
achieved with an 85% reduction in the
number of occupied hours above 60%
RH, compared to the baseline system
at 5 cfm/person - with only a $ 19/year
increase in energy cost - if the
economizer were eliminated. Source:
EPA Report, EPA 600/R-97-131,
November, 1997 EPA Contact: D.
Bruce Henschel, (919-541-4112,
bhenschel@engineer.aeerl .epa.gov)
Field Methods to Measure
Contaminant Removal Effectiveness
of Gas-Phase Air Filtration
Equipment; Phase 1 : Search of
Literature and Prior Art - Gas-phase
air filtration equipment (GPAFE) has
been used in HVAC systems for many
years. Traditionally it has been used
primarily for controlling odors
contained in outdoor air used for
building ventilation. Today, because of
the emphasis on good IAQ, GPAFE is
being used more and more for the
control of indoor gaseous and
vaporous contaminants that are known
or suspected to affect human health
and comfort. One of the problems
facing HVAC design engineers is how
to choose a test method to determine
the effectiveness of a gas-phase air
filtration device. Many different filter
systems and test methods are available
with differing test protocols,
instrumentation types and sensitivities,
and costs. This report, which is the
first phase of a two-phase research
project, presents the results of a
literature search into existing in-field
GPAFE effectiveness test methods
including required instrumentation and
costs. Source: EPA Report, EPA
600/R-97-092 (NTIS PB98-111677),
September 1997 (EPA Contact:
Russell N. Kulp, 919-541-7980,
rkulp@engineer.aeerl .epa.gov)
Inside IAQ, Spring/Summer 1998
Page 16
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Investigation of Contact Vacuuming
for Remediation of Fungally
Contaminated Duct Materials -
Environmental fungi can become a
potential IAQ problem when adequate
moisture and nutrients are present in
building materials. Because of their
potential to rapidly spread
contamination throughout a building,
ventilation system materials are of
particular significance as potential
microbial contamination sources.
Current recommendations are to discard
fibrous glass insulation that appears to
be wet or moldy. Unfortunately, this
advice is not always followed. Instead,
cleaning is sometimes used to remediate
fibrous glass duct liner that is
contaminated with microbial growth.
The objectives of this research program
were to: 1) determine, under dynamic
test conditions, whether fungal spore
levels on HVAC duct material surfaces
could be substantially reduced by
thorough vacuum cleaning, 2) evaluate
whether subsequent fungal growth could
be limited or contained by mechanical
cleaning, and 3) provide data
concerning the advisability of cleaning
duct materials. The constant high RH
environment to which the test materials
were exposed during this study was
selected as a favorable growth
environment that is frequently found in
the Southeastern U.S. The results
showed that following cleaning, the
levels of the two test fungi, A.
versicolor and P. chrysogenum,
recovered to precleaning levels within 6
weeks. Therefore, mechanical cleaning
by contact vacuuming alone was able to
only temporarily reduce the surface
fungal load. The current guidelines to
discard contaminated materials should
be followed. Source: Environment
International, 23, 6, 751-762, 1997
(EPA Contact: John Chang, 919-541-
3 747, j chang@engineer. aeerl .epa.gov.)
Personal Computer Monitors: A
Screening Evaluation of Volatile
Organic Emissions from Existing
Printed Circuit Board Laminates and
Potential Pollution Prevention
Alternatives - The printed circuit
board is a vital operating component in
many electronic products. They can be
found in personal computers (PC),
telephones, fax machines, and copiers.
Offgassing from the boards is most
prominent during the initial break-in
period when electrical heating occurs.
This is especially true in the case of PC
monitors where internal operating
temperatures can range from 60 to
70° C. In this evaluation, four types of
printed circuit board laminates
commonly found in PC monitors were
tested to determine if an alternative
laminate would be less emitting than
conventional laminates: 1) glass/
lignin-containing epoxy; 2) glass/
epoxy; 3) paper/phenol; and 4) paper/
reformulated phenolic. The purpose of
the screening evaluation was to
determine if the glass/ lignin-containing
epoxy resin and the reformulated
phenolic laminates would be less
emitting than conventional laminates
(paper/phenol). Glass/epoxy laminates
were included in the evaluation because
they exist primarily in central
processing units. The test results
qualitatively showed that the
glass/epoxy laminates and the
glass/lignin-containing epoxy resin
laminates emit fewer volatile
compounds than the two
paper/phenolic resin-based laminates.
Source: EPA Report. (EPA Contact:
Kelly W. Leovic, 919-541-7717,
kleovic@engineer.aeerl. epa.gov)
Predicting the Emissions of
Individual VOCs from Petroleum-
Based Indoor Coatings - The indoor
use of petroleum-based coating
materials may cause elevated VOC
concentrations. This paper presents a
newly developed mass transfer model
for estimating emissions of individual
VOCs from freshly coated surfaces.
Results of a four-step validation show
that the predicted individual VOC
emissions are in good agreement with
experimental data generated in small
chambers and an IAQ test house. The
values of the parameters introduced in
this model are all easily obtained and
thus its utilization can provide indoor
air quality professionals with emission
rate estimates for individual VOCs
without having to conduct costly
dynamic chamber testing. Source:
Atmospheric Environment, Vol. 32,
No. 2, pp. 231-237, 1998. (EPA
Contact: Zhishi Guo, 919-541-0185,
zguo@engineer. aeerl.epa.gov)
Radon Measurement and Diagnostic
Guidance for Large Buildings - This
manual is designed to assist architects,
engineers, and building owners,
operators, and maintenance staff to
incorporate radon mitigation into
building design, construction,
commissioning, operation, and
maintenance. This guidance for
evaluating building ventilation
dynamics, building air system balance
(including leakage rates of typical
residential, commercial, and public
structures), and HVAC components
and their effect on radon dilution and
indoor air should be of significant
benefit in improving IAQ. Source:
EPA Report, EPA-600/R-97-064aand
b (NTIS PB97-189716 and -724), July
1997 (EPA Contact: Marc Y.
Menetrez, 919-541-7981
mmenetrez@engineer.aeerl. epa.gov)
Inside IAQ, Spring/Summer 1998
Page 17
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Results of a Pilot Study to Evaluate
the Effectiveness of Cleaning
Residential Heating and Air
Conditioning Systems and the Impact
on IAQ and System Performance - To
evaluate the effectiveness of heating and
air-conditioning (HAC) system cleaning
in residences and its impact on IAQ and
system performance, a nine-home pilot
field study was conducted in the
Research Triangle Park area of NC
during the summer of 1996. All the
homes in the study had central (whole-
house) cooling systems and forced air
distribution systems with sheet metal
ducts. Background air monitoring and
sampling were performed at each home
for 3 days, then the air distribution
ducts and air handler components were
professionally cleaned by the National
Air Duct Cleaners Association
(NADCA) using methods and equip-
ment commonly used by industry.
Source removal was performed by
mechanical cleaning, and chemical
biocides were not used. The homes were
monitored again for 2 to 4 days
following cleaning. The impact of
mechanical cleaning without the use of
chemical biocides on the levels of
bacteria in samples collected from
surfaces of the HAC system was highly
variable. Fungal levels on HAC system
duct surfaces were generally higher than
bacterial levels. Mechanical cleaning
without the use of chemical biocides had
the most impact on the ducts with the
highest levels of fungi and noticeably
reduced the level of fungi on ductwork
surfaces in most houses. Results suggest
that, although the source of particulate
matter in the HAC system was
effectively removed, the magnitude of
the impact of HAC system cleaning on
particle concentrations could not be
quantitatively determined due to the
presence of other indoor sources,
occupant activity, and outdoor particle
sources. Airborne fiber concentrations
were low at all houses, precluding an
assessment of the impact of HAC
system cleaning on this parameter.
Measurements related to performance
of the HAC system suggest that
cleaning may improve system
performance. The medium volume dust
sampler developed for this study was
shown to be an effective tool for
quantitatively assessing HAC system
cleaning effectiveness. Source: EPA
Report, EPA-600/R-97-137, December
1997 (EPA Contact: Russell N. Kulp,
919-541-7980,
rkulp@engineer.aeerl.epa. gov)
The Application of Pollution
Prevention Techniques to Reduce
Indoor Air Emissions From Engin-
eered Wood Products - The objective
of this research was to investigate P2
options to reduce indoor emissions
from a type of finished engineered
wood. Emissions were screened from
four types of finished engineered wood
and alternative, lower emitting
substitutes were identified as potential
alternatives for the higher emitting
compounds. Three types of coatings
were found to have significantly lower
emission factors of summed VOCs and
formaldehyde relative to heat-curable
acid-catalyzed alkyd-urea coatings;
these included a two-component
waterborne polyurethane; a UV-
curable acrylate; and a UV- and heat-
curable multi-functional acrylate-free
emulsion. These coatings also had
comparable performance charac-
teristics to the heat-curable acid-
catalyzed alkyd-urea coatings. All three
wood coatings are currently available
in the market place. Three types of
engineered fiber panels were identified
as having significantly lower emission
factors of summed VOCs and
formaldehyde relative to those for
particleboard; these included MDF
made with MDI resin; a wheatboard
panel made with MDI resin; and a
panel made from recycled corrugated
cardboard. All three fiber panels are in
the market place and are used to
construct a wide variety of interior
products. See related article on page 8.
Source: EPA Report (EPA Contact:
Kelly W. Leovic, 919-541-7717,
kleovic@engineer.aeerl. epa.gov)
The Possible Role of Indoor Radon
Reduction Systems in Back-Drafting
Residential Combustion Appliances -
A computational sensitivity analysis
was conducted to identify the
conditions under which residential
active soil depressurization (ASD)
systems for indoor radon reduction
might most likely exacerbate or create
back-drafting of natural-draft
combustion appliances. Parameters
varied included: house size; normalized
leakage area; exhaust rate of exhaust
appliances other than the ASD system;
and the amount of house air exhausted
by the ASD system. Even with a
reasonably conservative set of
assumptions, it is predicted that ASD
systems should not exacerbate or
create back-drafting in most of the
U.S. housing stock. However, even
with a more forgiving set of
assumptions, it is predicted that ASD
systems could contribute to back-
drafting in some fraction of the
housing stock - houses tighter than
about 1 to 2 cm2/m2 - even in large
houses at minimal ASD exhaust rates.
It is not possible to use parameters
such as house size or ASD system
flow rate to estimate reliably the risk
that an ASD system might contribute
to back-drafting in a given house.
Spillage/back-draft testing should be
needed for essentially all installations.
Source: Indoor Air, 7: 206-214, 1997
(EPA Contact: D. Bruce Henschel,
919-541-4112, bhenschel@engineer.
aeerl. epa.gov)
Inside IAQ, Spring/Summer 1998
Page 18
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BACK ISSUES OF /HSIC/g IAQ ARE AVAILABLE:
+ Contents of Each Issue are Listed Below +
# FW-94
• Latex Paint Study
• Evaluation of FLEC Microchamber
• Bioresponse Testing
• EPA Buildings Study Program
• Sampling Method for Alveolar Exhaled
Breath
• Grab Sampling of Volatiles and
Semivolatile Organics
• Development of a Collection Fluid for
Bacteria
• Development of Media for Recovering
Fungi
• Health Effects of Organic Vapors
• The Effects of Indoor Air Pollutants on
Susceptible Populations
• IAQ Modeling
• Reducing Indoor Air Contamination
from Textiles Through Pollution
Prevention
#SS96
• lEMB's Large Chamber
• Effects of HVAC Fan Cycling on the
Performance of Paniculate Air Filters
• Reducing Indoor Air Emissions from
Engineered Wood Products
• Cost-Effectiveness of Alternative IAQ
Control Techniques
• Quality Assurance for EPA's IAQ
Research
• Emissions of Carbonyl Compounds from
Latex Paint
# SS-95
• Evaluation of Emissions from Latex
Paint
• Carpet Freshener Study
• EPA Compares Large Chamber Design
With International Chambers
• Development of a Medium for
Recovering Aerosolized Bacteria
• Irritation of the Nasal Septum
• EPA Researches Office Equipment
• Evaluation of Fungal Growth On Ceiling
Tiles
• Influence of Climatic Factors on House
Dust Mites
• Ventilation Research Program
• EPA Begins Air Duct Cleaning Research
• Cost Analysis of IAQ Control
Techniques
# FW-96
• Cost Analysis of VOC Air Cleaners:
Activated Carbon vs. Photocatalytic
Oxidation
• Evaluation of VOC Emissions from an
Alkyd Paint
• Reducing Solvent and Propellant
Emissions from Consumer Products
• Possible Role of Radon Reduction
Systems in Combustion Product Spillage
All issues contain summaries of recent
publications.
# FW-95
• Evaluation of an IAQ Source
Management Strategy for a Large
Building
• EPA Examines Indoor Emissions from
Conversion Varnishes
• Review of Concentration Standards and
Guidelines for Fungi in Indoor Air
• Two Case Studies Evaluating HVAC
Systems as Sources of Bioaerosols
• Effect of Ventilation on Radon Levels in
a Municipal Office Building
• Indoor Air Bibliographic Database
• Using Animal Models to Understand
Human Susceptibility to Indoor Air
• Reducing Indoor Air Emissions from
Aerosol Consumer Products
• Summaries of 1995 "Engineering
Solutions to IAQ Problems" Symposium
Papers
# SS-97
• VOC Emissions from Latex Paint: Sink
Effects
• The Effectivness of Antimicrobial
Surface Treatments
• Field Study on Residential Air Duct
Cleaning
• Emissions from Acid-Catalyzed
Varnishes
• Measuring Toner Emissions Using
Headspace Analysis
• A Large Chamber Test Method for
Measuring Emissions from Office
Equipment
• Summaries of 1997 "Engineering
Solutions to IAQ Problems" Symposium
Papers
Complete this form and and mail to address below - Material will be mailed postage paid.
Name
Address
Check appropriate box(s) to indicate which issue(s) wanted: G FW-94 G SS-95 G FW-95 G SS-96 G FW-96 G SS-97
Mail to Inside IAQ , U.S. EPA, MD-54, Research Triangle Park, NC 27711, or Fax to 919-541-5485 .
Inside IAQ, Spring/Summer 1998
Page 19
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GLOSSARY OF ACRONYMS
ACH - Air Exchange Per Hour
ASD - Active Soil Depressurization
DNPH - Dinitrophenylhydrazine
DOE - Department of Energy
GAC - Granulated Activated Carbon
GPAFE - Gas-phase Air Filtration Equipment
HAC - Heating and Air Conditioning
HAP - Hazardous Air Pollutants
HB - Hardboard
HBVSST - hardboard coated and cured with a stain, and a
heat-curable acid-catalyzed alkyd-urea sealer and topcoat
HUD - Housing and Urban Development
HVAC - Heating, Ventilation, and Air Conditioning
IAQ - Indoor Air Quality
IEMB - Indoor Environment Management Branch
I/O - Indoor/Outdoor
MDI - Methylene diisocyanate
MEK - Methylethylketone
MFD - Medium Density Fiberboard
MSDS - Material Safety Data Sheet
NOPES - Nonoccupational Pesticide Exposure Study
NRMRL - National Risk Management Research Laboratory
OA - Outdoor Air
OAQPS - Office of Air Quality Planning and Standards
PB - Particleboard
PBVST - particleboard coated and cured with a heat-curable
acid-catalyzed alkyd-urea sealer and topcoat
PC - Personal Computer
PCO - Photocatalytic Oxidation
PF - Phenol - Formaldehyde
P2 - Pollution Prevention
PVB - Veneered Particleboard
RH - Relative Humidity
RTI - Research Triangle Institute
TVOC - Total Volatile Organic Compound
UF - Urea - Formaldehyde
UV - Ultraviolet
VOC - Volatile Organic Compound
United States
Environmental Protection Agency
National Risk Management Research Laboratory
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Research Triangle Park, NC 27711
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