Inside IAQ, Spring/Summer 1998 Page 1

United States Environmental Office of Research and Development

Protection Agency Research Triangle Park, NC 27711

EPA/600/N-98/002 Spring/Summer 1998

 EPA Inside IAQ

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

name and address to;

Inside IAQ, Att. 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

CONCENTRATIONS OF HAZARDOUS AIR POLLUTANTS

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 μm, and especially less than 2.5 μm). Air that enters

a building through infiltration is, in general, cleaned very little as it

penetrates openings in the building envelope. Literature on outdoorto-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., JAPCA 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 2

! 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-ofmagnitude 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

Literature survey

Outdoor concentrations

U.S. ambient air data through 1986

Samfield, 1992 Literature survey

Indoor concentrations

U.S. and foreign data through late 1980's data on

residences, office buildings, schools, other commercial

buildings

Brown et al., 1994 Literature survey, Indoor concentrations

I/O ratios

Comprehensive compilation and analysis of U.S. &

European literature, data on residences, office buildings,

schools, and other buildings

Kelly et al., 1994 Literature survey

Outdoor concentrations

Comprehensive update of Shah and Singh, 1988

EPA Nonoccupational

Pesticide Exposure

Study (NOPES) 1990

Field study of pesticides

Indoor concentrations, Outdoor

concentrations, I/O ratios

Approximately 350 samples from homes in Jacksonville,

FL and Chicopee-Springfield, MA

Sheldon et al., 1992 Field study, Indoor concentrations,

Outdoor concentrations, I/O ratios

128 homes in Woodland, CA

Daisey et al.,

1994

Field study, Indoor concentrations,

Outdoor concentrations, I/O ratios

12 office buildings in northern CA with 3 different types of

ventilation systems

Shields et al.,

1996

Field study, Indoor concentrations,

Outdoor concentrations, I/O ratios

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 3

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

et al., Atm. Environ., 28(22): 3563-3569, 1994) of 757 homes

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 4

TABLE 1. Summary of Reported Indoor Concentrations of Selected HAPs (μg/m3)

Survey Articles or Reports Individual Studies

HAP

Shah and Singh

(1988)

 Mean Median

Samfield (1992)

 Avg of Avg of

 Medians Means

Brown et al.

(1994)

WA, GMa

NOPES (1990)

Average of

Wghtd Arith

Means

 J’villeb Spr/Chicc

Sheldon

et al. (1992)

Median

Daisey et al.

(1994)

GM

Shields et

al. (1996)

Avg of 

GMs

“Typical”

Value

Acetaldehyde* 9.6 <10

Benzene* 17 10 8 8.2 8 2.2 3.2 5

Captan 0.00185 0.001 0.0001 <0.001

Carbon

 Tetrachloride* 25 0 <4 12 0.5 <5

Chlordane 3.3 2.8 0.26 0.12 0.2

Chloroform* 2.9 0.5 >8 8 10 <1.2 1

Cumene 5.1 1

2,4-D (salts, esters) 0.0018 0.001 0.001 0.001

DDE 0.0003 0.0008 0.0005

Dichlorvos 0.07 0.082 0.003 0.05

Ethylbenzene 13 4.9 2.8 13.8 5 2.2 2 5

Formaldehyde* 62 52 92 50

Heptachlor 1.2 0.7 0.13 0.017 0.1

Hexachlorobenzene 0.000126 0.0007 0.0001 <<0.8 0.0005

Hexane 5 33 12, 5 2 5

Methoxychlor 0.0002 0 0.0001

Methyl Ethyl Ketone 28 21 5.3 7 4, 21 10

Methylene Chloride 342 17 15 1.4 10

Naphthalene <0.4 11 1

Paradichlorobenzene 24 1.7 <2 31 8 1 ~0.1 1

Propoxur 0.093 0.34 0.3 0.022 0.1

Radionuclides/Rn** 2

Styrene* 1.2 1.8 1 1.7 ~2 2

Tetrachloroethylene* 21 5.1 <4 9.5 7 0.3 2 5

Toluene 28 6.3 42 56 37 10 7 20

Trichloroethylene* 7.4 0.7 <1.4 5.9 47*** <0.3 9.8 5

Xylenes (o+m+p) ~12 ~25 24 6 12 ~7 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 5

TABLE 2. Summary of Reported Outdoor Concentrations of Selected HAPs (μg/m3)

Survey Articles Individual Studies

HAP

Shah and

Singh (1988)

Median

Kelly et al.

(1994)

Median or

Range

NOPES (1990)

Average of

Weighted Arith Means

J’ville a Spr/Chicb

Sheldon et al.

(1992)

Median

Shields et al.

(1996)

GeoMean

“Typical”

Value

Acetaldehyde* 2.4 2.7 <3

Benzene* 5.4 5.1 1.1 5

Captan ND ND ND <0.0001

Carbon Tetrachloride* 0.77 0.8 0.5 1

Chlordane ND-0.63 0.025 0.0025 0.01

Chloroform* 0.29 0.2 0.2

Cumene 0.2 0.2

2,4-D (salts, esters) ND-0.004 0.00003 ND 0.00003

DDE ND-0.13 ND ND <0.002

Dichlorvos ND-0.15 0.001 ND 0.001

Ethylbenzene 1.1 1 1

Formaldehyde* 5.1 3.3 4

Heptachlor ND-0.63 0.015 0.0002 0.002

Hexachlorobenzene ND-0.013 0.00007 ND <<0.8 0.0001

Hexane 3.8 4

Methoxychlor ND-0.007 0.00003 ND 0.00003

Methyl Ethyl Ketone ND <1

Methylene Chloride 2.7 0.5 <2.8 1

Naphthalene 1.2 1.2 1

Paradichlorobenzene 0.26 ND <0.3 <0.05 <0.05

Propoxur 0.001-0.2 0.045 0.0004 0.01

Radionuclides/Rn** (0.07-0.2) 0.1

Styrene* 0.6 <0.2 0.6

Tetrachloroethylene* 2.4 1.7 <0.3 0.5 2

Toluene 7.2 8.6 2.6 5

Trichloroethylene* 0.86 0.4 <0.3 0.5

Xylenes (o+m+p) 10.7 2.3 ~3.4 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 6

TABLE 3. Summary of Reported Indoor/Outdoor Concentration Ratios of Selected HAPs (μg/m3)

HAP

Sheldon et al.

(1992)

GeoMean

Brown et al.

(1994)

GeoMean

Daisey et al.

(1994)

Range

Shields et al.

(1996)

Avg. of Geo.

Means “Typical” Ratio

Acetaldehyde* 5 5

Benzene* 2.1 3 0.25-4.2 2

Captan

Carbon Tetrachloride* 1 2 2

Chlordane

Chloroform* 5 5

Cumene

2,4-D (salts, esters)

DDE

Dichlorvos

Ethylbenzene 6 0.48-2.5 2.1 3

Formaldehyde*

Heptachlor

Hexachlorobenzene

Hexane 9 0.26-18 10

Methoxychlor

Methyl Ethyl Ketone 4 4

Methylene Chloride 6 1.0-45 10

Naphthalene 4 4

Paradichlorobenzene 6.9 5 5

Propoxur

Radionuclides/Rn**

Styrene* 4.1 10 0.69-13 5

Tetrachloroethylene* 1.8 5 2.8 3

Toluene 6 0.63-5.2 3 5

Trichloroethylene* 6 1.7-84 5

Xylenes (o+m+p) 2.4 6 0.5-3.5 ~2 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 7

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.

Typical Concentration*** Typical Daily Exposure#

HAP References

Indoor

(μg/m3)

Outdoor

(μg/m3) I/O Ratio

Indoor

(μg/m3Ch)

Outdoor

(μg/m3Ch) I/O Ratio

Acetaldehyde* a,b,g <10 <3 [5] <216 <7.2 [50]

Benzene* a,b,g,ef,h 5 5 [2] 108 12 [20]

Captan c,a,b <0.001 ND@ 10 <0.02 <0.0002 ~100

Carbon Tetrachloride* a,b,g,h <5 1 [2] <108 2.4 [20]

Chlordane c 0.2 0.01 20 4.32 0.024 200

Chloroform* a,b,e,g,h 1 0.2 [5] 21.6 0.48 [50]

Cumene a,b 1 0.2 5 21.6 0.48 50

2,4-D (salts, esters) a,c,b 0.001 0.00003 30 0.0216 0.000072 300

DDE c 0.0005 <0.002 >0.2 0.0108 <0.005 >2

Dichlorvos c,b 0.05 0.001 50 1.08 0.0024 400

Ethylbenzene a,d,b,g,e,f 5 1 [3] 108 2.4 [30]

Formaldehyde a,b,g 50 4 10 1080 9.6 100

Heptachlor c 0.1 0.002 50 2.16 0.0048 400

Hexachlorobenzene c,b 0.0005 0.0001 5 0.0108 0.00024 50

Hexane a,b,e,f 5 4 [10] 108 9.6 [90]

Methoxychlor c 0.0001 0.00003 3 0.00216 0.000072 30

Methyl Ethyl Ketone a,b,e,g 10 <1 [4] 216 <2.4 [40]

Methylene Chloride a,g,e,f,h 10 1 [10] 216 2.4 [90]

Naphthalene a,b 1 1 [4] 21 2.4 [40]

Paradichlorobenzene a,d,b,e,h 1 <0.05 [5] 21.6 <0.12 [50]

Propoxur c,a,b 0.1 0.01 10 2.16 0.024 90

Radionuclides/Rn ** a 2 0.1 20 43.2 0.24 200

Styrene* a,b,d,f,h 2 0.6 [5] 43.2 1.44 [50]

Tetrachloroethylene* a,d,b,e,e,g 5 2 [3] 108 4.8 [30]

Toluene a,c,b,d,e,f, 20 5 [5] 432 12 [50]

Trichloroethylene* a,b,g,f,h 5 0.5 [5] 108 1.2 [50]

Xylenes (o+m+p) a,d,b,e,f 15 10 [2] 324 24 [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 (μg/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 et al., 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 8

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 HB are made from wood fibers. In the

U.S., most interior-grade PB and MDF are bonded with ureaformaldehyde (UF) resins; hardboard is bonded with phenolformaldehyde (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 (RTI) 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 EC, 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 Center in

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 EC, 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 Page 9

TABLE 5. Selected Engineered Panels

Panel

Identification Fiber Source Resin Source Interior Applications

A Recycled newspaper None floors, walls , subfloors, roof decking, filler board for furniture

B Wheat straw MDIa PB applications such as furniture, cabinetry, shelving

C Recycled corrugated cardboard None furniture, store displays, countertops, shelving, etc.

D Lumber and plywood residuals MDI MDF applications such as furniture, cabinetry, shelves

E Lumber and plywood residuals UF MDF applications such as furniture, cabinetry, shelves

F Lumber and plywood residuals UF PB applications such as furniture, cabinetry, shelves, floor

underlayment, stair treads

N Lumber and plywood residuals PF PB applications such as furniture, cabinetry, shelves, floor

underlayment, stair treads

a MDI = Methylene diisocyanate

TABLE 6. Selected Coatings Systems

Coating 1 Coating 2 Coating 3 Coating 4 Coating 5 Coating 6

Chemistry Acid-catalyzed

alkyd-urea

Two-component

polyurethane

Non-air-inhibited

unsaturated

polyester

Acrylate Multi-functional

acrylate-free

emulsion

Polyurethane

dispersion

Carrier organic solvents water water none water water

Cure method heat heat UV light UV light heat + UV light 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 EC, 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 dinitrophenylhydrazine (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 10

0

100

200

300

400

500

600

A1-1A2-2A3-1A3-2

B1-1 

B2-1B2-2B3-1C1-1C1-2C2-2C3-2

D1-1D2-2D3-1D3-2

E1-2E2-2E3-1E3-2

F1-1F1-2F2-2F3-2

N1-2N2-1N2-2N3-1

Formaldehyde

TVOC

Mean Estimated Emission Factor, μg/(m2 · hr)

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 UFbonded 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 lowemitting 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 acidcatalyzed 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 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 11

TABLE 7. Mean Emission Factors for Uncoated and Coated Test Squares

Mean Emission Factors, μg/(m2Chr)

Uncoated test

squares of PBV 

Test Squares Coated and Cured with

Compounds Coating 1 Coating 2 Coating 3 Coating 4 Coating 5 Coating 6

Formaldehyde 140 400 20 70 18 19 33

Acetaldehyde 61 53 41 65 68 41 68

Acetone 420 520 490 380 390 430 510

Propionaldehyde 21 16 15 16 16 12 17

2-Butanone - 

a

- - - - - -

Butyraldehyde 15 - - 18 - - 12

Benzaldehyde 23 - - 30 14 18 23

Valeraldehyde 65 37 26 54 28 19 57

m-Tolualdehyde - - - - - - -

n-Hexanal 410 150 120 280 79 93 350

1-Pentanol 62 150 16 38 13 14 49

Limonene 79 68 54 74 38 37 83

Junipene 89 61 24 54 16 13 67

Terpenes 170 320 220 170 110 100 120

1-Butanol 6 800 - 5 - 8 7

Toluene - 16 - 5 22 - 6

2-Methyl-1-butanol - 55 - - - - -

Butyl acetate - 38 - - - - -

1,2-Propanediol - 15 - 33 - - -

Ethylbenzene - 270 - - 33 - -

m,p-Xylene - 660 - - 110 - -

2-Heptanone 15 550 8 13 9 7 22

o-Xylene - 210 - - 32 - -

Propylbenzene - 91 - - - - -

Ethyl 3-ethoxypropionate - 111 - - - - -

1-Methyl-2-pyrrolidone - 11 - 20 - 5 2400

2-(2-Butoxyethoxy)ethanol 8 1700 43 610 18 6 7

Naphthalene - 24 - - - - -

Hexyl acetate - 400 - - - - -

Indan - 13 - - - - -

C3-Benzenes - 1100 - - - - -

C4-Benzenes 34 190 25 33 17 16 33

Dipropylene glycol, methyl ether - - - - - 24 240

Unknown 1 - - - 180 - - -

Unknown 2 - - - 260 - - -

TVOCb 1000 5200 610 1700 810 540 2800

Summed VOCsc 1600 7800 1100 2300 1000 900 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 μg/(m2

Chr)

b TVOC = total volatile organic compounds from TVOC analysis of multisorbent cartridges 

cSummed VOCs are the sum of emission factors > 5 μg/(m2

Chr), rounded to two significant figures
Inside IAQ, Spring/Summer 1998 Page 12

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 shutdown), 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 m 2 (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 oF); 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 elevatedRH 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 oF would add only $10/year to energy costs, and

would provide some modest reduction in unoccupied elevatedRH hours. Set-up to 79 oF 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 overestimated, 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 13

COST ANALYSIS OF INDOOR AIR 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 perpass 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 configuration–involving a series of 2.5-cm-thick GAC panels in a Vbank 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 μmol/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 9,000W 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

m

3

/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 14

PARTICULATE FILTER

 to protect fan and coils

 (unit illustrated is 10 cm thick

 pleated filter, ASHRAE 30)

GAC FILTER AND

FILTER HOUSING

(0.6 x 0.6 x 0.3 m)

RETURN DUCTING

(0.6 x 0.6 m cross section)

12 panels containing granular

charcoal, 2.5 cm thick

Return air from

occupied space

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.

12 panels of substrate (each 0.6 x 0.3 m)

coated with TiO2 photocatalyst:

Ceramic foam (4 pores/cm), 2 cm thick

One medium-pressure mercury bulb operated at:

750 W 1,500 W PARTICULATE FILTER

to remove TiO2 particles

(illustrated is a pleated

filter, ASHRAE 30)

PCO REACTION UNIT

AND HOUSING (1 of 6)

(0.6 x 0.6 x 0.3 m)

PARTICULATE

FILTER

to protect fan

Unit #1

Return

air

25 °C

Unit #2 Unit #6

To fan

and coils

33 °C

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.

FIGURE 2. GAC VOC air cleaner (side view).

FIGURE 3. Model PCO VOC air cleaner (side view).
Inside IAQ, Spring/Summer 1998 Page 15

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

pressure)

 60 20

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 16

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

μm, 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

EF); 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 17

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-

3747, jchang@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

70E 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 PetroleumBased 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-97-064a and

b (NTIS PB97-189716 and -724), July

1997 (EPA Contact: Marc Y.

Menetrez, 919-541-798 1

mmenetrez@engineer.aeerl. epa.gov)
Inside IAQ, Spring/Summer 1998 Page 18

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 (wholehouse) 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 equipment 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 Engineered 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 UVcurable acrylate; and a UV- and heatcurable multi-functional acrylate-free

emulsion. These coatings also had

comparable performance characteristics to the heat-curable acidcatalyzed 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 backdrafting 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 19

BACK ISSUES OF Inside IAQ ARE AVAILABLE:

g Contents of Each Issue are Listed Below g

# 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

• IEMB’s Large Chamber

• Effects of HVAC Fan Cycling on the

Performance of Particulate 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.

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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 .
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

MD-54

Research Triangle Park, NC 27711

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