Inside IAQ, Spring/Summer 2003 Page 1

Indoor Air Quality Problems and

Engineering Solutions

Symposium and Exhibition

July 21-23, 2003

Research Triangle Park, NC

(See Page 1 for Details)

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United States Environmental Office of Research and Development

Protection Agency Research Triangle Park, NC 27711

EPA-600/N-03/005 Spring/Summer 2003 

 EPA Inside IAQ

EPA's Indoor Air Quality Research Update

In This Issue Page

Indoor Air Quality Symposium ................... 1

Estimation of Overall Mass Transfer Coefficient 

for VOC Emissions from Aqueous Solutions ..... 2

BioLab Begins Operation ....................... 4

Emissions from Popping and Opening 

Microwave Popcorn .......................... 5

Evaluation of Coatings to Minimize Potential Dermal

Exposure to Arsenic on Pressure Treated Wood

(CCA) ....................................... 6

Summaries of Recent Publications ................ 7

News from NERL ............................ 11

Glossary ................................... 12

INDOOR AIR QUALITY SYMPOSIUM

Indoor Air Quality Problems and Engineering Solutions,

an international symposium cosponsored by the U.S.

EPA’s Office of Research and Development and the

A&WMA (Air and Waste Management Association),

will be held July 21-23, 2003, in Research Triangle Park,

NC, at the Sheraton Imperial Hotel and Convention

Center.

H.E. Barney Burroughs, renowned expert in the field of

indoor environmental quality, will deliver the keynote

address. This year’s symposium will include sessions on

such timely and relevant topics as: Safe Buildings for

Homeland Security, Mold and Biocontaminants, Indoor

Pollutant Sources, Models and Databases, Particulate

Matter, Air Cleaning, IAQ Problems from Polluted Soil

and Water, Special Topics, and Product Certification.

The technical program will include 60 presentations,

with parallel sessions on one day, July 22. Poster

sessions and an exhibition of related products and

services are planned. A reception is also planned for the

first evening. The conference site has convenient access

to RDU airport, nearby restaurants, shopping, and

entertainment.

Two excellent, professional development courses will

be offered on July 20, 2003: How to Assess & Improve

Indoor Air Quality by Rishi Kumar and Mold in the

Indoor Environment by Richard Shaughnessy and

Kenneth Martinez.

(Continued on Page 2)
Inside IAQ, Spring/Summer 2003 Page 2

Immediately following the symposium, a tour of the U.S.

EPA’s beautiful, new, state-of-the-art, “green” research

facilities, shown in the accompanying photo, will be

offered.

We are looking forward to an interesting, exciting

symposium, and we hope you can join us. For further

information on the program and registration, visit

A&WMA’s web site atwww.awma.org/events or contact

Denise Stotler at (412) 232-3444, ext. 3111,

stotler@awma.org. Registration discounts are available

for A&WMA members, students, and government

employees. For information on the exhibition, contact

Gene Garbowsky, A&WMA, (412) 232-3444, ext. 3102,

ggarbowsky@awma.org. For further information on the

technical program, contact Jim Jetter at (919) 541-4830,

jetter.jim@epa.gov.

ESTIMATION OF OVERALL MASS TRANSFER

COEFFICIENT FOR VOC EMISSIONS FROM

AQUEOUS SOLUTIONS

The abilityto estimate volatile organic compound (VOC)

emissions from water and water-based products is of

great significance for indoor air quality because many

household products (e.g., pesticides, hard-surface

cleaners, and some aerosol products) are aqueous

solutions. It is well established that predicting VOC

emissions from these products requires knowledge of the

Henry’s law constant and overall mass transfer

coefficient (also known as total transfer velocity):

(1)

(2)

where:

 

 R = emission rate (:g/h),

S = source area (m2),

KOL = overall liquid-phase mass transfer coefficient 

 (m/h),

Figure 1 EPA’s new “green” research facilities

KOG = overall gas-phase mass transfer coefficient (m/h),

CL = pollutant concentration in liquid (:g/m3),

CG = pollutant concentration in air (:g/m3

), and

H = dimensionless Henry’s constant [(:g/m3

)air/

(:g/m3

)liquid].

The two overall mass transfer coefficients,KOL and KOG,

are defined by Eqs. 3 and 4, respectively:

(3)

 (4)

where:

kL = liquid-phase mass transfer coefficient (m/h), and

kg = gas-phase mass transfer coefficient (m/h).

KOL and KOG are so closely related that one can regard

them as the measurement of the same physical property

on different scales, a case similar to weighing an object

in kilograms and pounds. The conversion factor

between KOL and KOG is the Henry’s constant (Eq. 5):

(5)

(Continued on Page 3)
Inside IAQ, Spring/Summer 2003 Page 3

Methods for estimating the overall mass transfer

coefficients are available for ambient sources, such as

oceans, lakes, and water treatment facilities. However,

these methods cannot be applied to the indoor

environments without certain adjustments because the

indoor and outdoor conditions are very different. For

instance, indoor sources are much smaller and shallower,

and the indoor air movements are not as strong as the

outdoor. There are no methods for estimating the overall

mass transfer coefficient for small pools, puddles, and

wet films that are often found in the indoor

environments. To fill this data gap, we conducted a

series of small chamber tests to experimentally determine

the overall mass transfer coefficients for six compounds

with the Henry’s law constants (air/water partition

coefficients) ranging from 3.33×10-7 to 3.67×10-3 (atm

m3/mol). The estimated overall liquid-phase mass

transfer coefficients for still solutions varied from

1.8×10-6 to 5.7×10-3 m/h; the estimated liquid-phase mass

transfer coefficients were 9.78×10-3 m/h for the

reference compound (oxygen) and 5.00×10-3 to 6.04×10-

3 m/h for the test compounds. 

An empirical method is proposed to estimate the overall

mass transfer coefficient for still water solutions in the

indoor environments. It consists of three steps: (1)

estimate the gas-phase mass transfer coefficient (kg

)

from the dimensionless Sherwood number, (2) estimate

the liquid-phase mass transfer coefficient (kL) from Eq.

6, and (3) calculate the overall mass transfer coefficient

from Eqs. 3 or 4. 

(6)

where:

kL(X) = liquid-phase mass transfer coefficient for 

 compound X (m/h),and 

DL

(X) = diffusivity in water for compound X (m2/h). 

Figure 2 compares the predicted values with those

estimated from the chamber data.

Although not difficult, the calculations of the proposed

method are somewhat tedious. We have developed a

computer program to handle all the calculations,

including estimations of molecular diffusivity in air and

water.

As a practical matter, researchers often want to know

under what conditions KOL can be approximated by

either kL or kg. There have been many discussions on

this matter for the ambient environment. In general, it

depends on whether the gas- or liquid-phase mass

transfer resistance is dominant in the overall mass

transfer resistance (1/KOL or 1/KOL). Using the results of

this work, Figure 3 illustrates the contribution of the

gas-phase mass transfer resistance 1/(H kg

) to 1/KOL as

a function of H and kg

. For still water under typical

indoor environmental conditions, we suggest thatKOL be

approximated by kL when H > 10-1 and by kg when H <

10-4, where H is dimensionless (i.e., air/water partition

coefficient). For more information, contact Zhishi Guo,

919-541-0185, guo.zhishi@epa.gov.

Figure 2. Comparison between experimental and

calculated overall liquid-phase mass transfer

coefficients. The solid line represents linearity.

Figure 3. Contribution of the gas-phase mass

transfer resistance (GMTR) to the overall mass

transfer resistance (1/KOL). The curves from left to

right are for kg

 = 10, 5, 2, and 1 m/h, respectively.
Inside IAQ, Spring/Summer 2003 Page 4

BIOLAB BEGINS OPERATION

The BioLab (BL) is a component of the Indoor

Environment Management Branch of APPCD/NRMRL.

The BL facility is a new state-of-the art BSL 2

microbiology research laboratory that performs research

in the evaluation of biocontaminants such as mold,

bacterial spores, toxins (mycotoxins, endotoxins), and

allergens that have been recognized as the most common

cause of building related illnesses. The BL facility is

equipped with an ABI Genetic Sequencer for the analysis

of DNA and RNA sequences; a BioRad iCycler for

amplifying DNA and RNA fragments usingRT-PCR; the

BIOLOG system for identification of mold and bacteria,

Qcount an automated colony counter, as well as other

supportive equipment in a microbiological laboratory. 

In April 2003, the first draft of the BL Facility Manual

was placed at the Network Neighborhood\Saturn\Public\

APPCD\Facility Manuals.

Bioaerosol Sampling and Mold Analysis (In-House)

As the BL begins operations the initial focus will be on

bioaerosol sampling of ambient and mold contaminated

environments. Work will focus on optimizing sampling

techniques, capture of airborne mold particles, and

subsequent growth and enumeration technologies.

Bioaerosol sampling will be conducted in diverse

environments using an Andersen Cascade Impactor,

Zefon Air-O-Cell filter cassettes, and Millipore aerosol

analysis filters. Mold spores will be eluted from the

capture membranes and enumerated by growth culture

and Quantitative Polymerase Chain Reaction.

Sequencing various genes on the ABI 3100 Genetic

Analyzer in concert with BIOLOG analysis will

complete identification of mold species by generating a

molecular and physiological “fingerprint” for each

organism. Currently, universal primers have been

developed that will amplify portions of the 18S and 28S

ribosomal subunits of various mold contaminants such

Aspergillus, Penicillium, Cladosporium, and

Stachybotrys spp. Amplification of this fragment will

allow the region to be sequenced and individual base

positions to be determined. It is the differences in the

individual base positions that will be used to identify

different species and different strains of the same

species. 

Microbial Survivability Test for Medical Waste

Incinerator Materials: 

The thermal destruction project, funded by the

Department of Homeland Security, is another on-going

research project in the BioLab in collaboration with

APTB. The objective of this project is to determine the

microbial survivability of Bacillus anthracis surrogates

in building materials during the normal operation of a

medical waste incinerator. 

The BL facility will be in charge of the sample

preparation (both sterile and inoculated building

materials) as well as the post-incineration and exhaust

air analysis. Samples to be incinerated will consist of

various building materials inoculated with Bacillus

surrogate spores. Post incineration materials will be

analyzed for microbial survivability. The in-house

analytical resources that will be used for pre/post

incineration analyses are the BIOLOG microbial

identification system and the QCount. 

The main goal of this project is to determine the most

efficient incineration method to destroy Bacillus

anthracis spores.

For more information, contact Marc Menetrez, (919)

541-7981, menetrez.marc@epa.gov; Timothy Dean,

(919)541-2304, dean.timothy@epa.gov; Doris

Betancourt, (919)541-9446, betancourt.doris@epa.gov

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

U.S. EPA, NRMRL - MD E305-03

Research Triangle Park, NC 27711

Fax: 919-541-2157

E-Mail: inside_iaq@epa.gov

Also, check our home page on the Internet at:

htlp//www.epa.gov//appcdwww/crb/
Inside IAQ, Spring/Summer 2003 Page 5

EMISSIONS FROM POPPING AND OPENING

MICROWAVE POPCORN

In 2000, eight workers at a microwave popcorn

production plant in Missouri were diagnosed with the

rare disease bronchiolitis obliterans (Kreiss et al.,

2002). Patients were as young as 26 years old (Parmet

and Von Essen, 2002). As a result of this disease, at

least four of these workers are on lung transplant lists

(Kullman et al., 2002). Since the initial discovery,

workers in at least six other microwave popcorn plants

have been documented to have bronchiolitis obliterans

(Kreiss et al., 2002). 

The Missouri plant employees have 3.3 times the

national rate of obstructive disease for smokers and

10.8 times the national rate for non-smokers (Kreiss et

al., 2002). Workers in microwave production areas,

including quality control personnel who pop corn and

open bags, had higher incidence of respiratory and

dermal symptoms (Kreiss et al., 2002). Discussions

with National Institute for Occupational Safety and

Health (NIOSH) scientists from Morgantown, WV

confirm that workers in quality control areas have

shown an increased risk of lung disease (Kullman,

2002; Kreiss, 2002). This may be due to the peak

exposures received when popping and opening a bag of

flavored popcorn.

The microwave popcorn production plant receives raw

corn; mixes the corn with salt, oil, and flavorings; and

packages it for microwave use (Parmet and Von Essen,

2002). The flavorings emit compounds such as

diacetyl, other ketones, acetoin, and 2-nonanone

(Kullman et al., 2002). While diacetyl was measured

as marker for flavoring vapors, more than 100 volatile

compounds were identified (Kreiss, 2002). Diacetyl is

not listed as a workplace chemical hazard in NIOSH

Pocket Guide to Chemical Hazards (Parmet and Von

Essen, 2002), and no OSHA permissibleexposure limit

(PEL) or NIOSH recommended exposure limits exist

for diacetyl. Particulate matter levels were below

exposure limits for particulates not otherwise regulated

(Simoes et al., 2002a; Simoes et al., 2002b).

The U.S. Food and Drug Administration regulates

flavorings based on ingestion safety, not on inhalation

safety (Simoes et al, 2002a; Simoes et al, 2002b); thus,

inhalation toxicology studies on popcorn flavorings

had not been performed. Recent animal studies by

NIOSH scientists found that butter flavoring vapors that

produce diacetyl levels of 352 ppm severely damaged

the respiratory epithelium of rats (Hubbs et al., 2002).

It is feasible that recurrent exposure in the home

environment may pose similar risks, especially in

children and adults with compromised respiratory

health.

Comprehensive sampling has not been performed to

determine contaminants released when flavorings are

heated to microwave temperatures. Thus, the primary

goal of this work is to identify and quantify

contaminants emitted while popping and opening a bag

of microwave popcorn. Discussions with NIOSH

scientists indicate that microwave popcorn flavorings,

when heated, may produce a more complex spectra of

compounds resulting in a higher exposure risk

(Kullman, 2002; Kreiss, 2002). As no data is currently

available to support this theory, the secondary goal of

this work is to complete a mass balance on compounds

found in microwave popcorn by comparing pre-pop

extraction data with popping emissions and post-pop

extraction data.

 

This project will proceed in two phases. Phase I will be

exploratory in nature. In this phase we will identify the

compounds emitted while popping and opening popcorn

and will make estimates of compound concentrations.

Compounds of particular interest include diacetyl,

acetoin, butyric acid, and 2-nonanone. In addition to

identifying and quantifying compounds emitted into the

air, procedural and analytical details (e.g., surrogate

choices, sampling volumes, extraction volumes, and

flow rates) will be refined. Phase I will be performed in

a small box-like chamber of sufficient size to hold a

microwave oven. This chamber is being built

specifically to accommodate this study.

Phase II will quantitatively evaluate the emitted

compounds identified in Phase I for both corn popping

and bag opening. In addition, a mass balance will be

performed with Phase II data to determine whether the

sum of contaminants released during popping and

present after-popping are different in type or amount

than those present in pre-popped microwave popcorn.

Phase II will also evaluate whether the microwaveable

(Continued on Page 6)
Inside IAQ, Spring/Summer 2003 Page 6

bag used for popcorn emits VOCs during

popping/heating. Phase II will also be performed in the

small box-like chamber built for this study. 

Research is expected to be completed by December of

2003.

For more information, contact Jacky Rosati, (919) 541-

9429 ( rosati.jacky@epa.gov)

References:

Hubbs, A.F., Battelli, L.A., Goldsmith, W.T., Porter,

D.W., Frazer, D., Friend, S., Schwegler-Berry, D.,

Mercer, R.R., Reynolds, J.S., Grote, A., Castranova,

V., Kullman, G., Fedan, J.S., Dowdy, J., Jones, W.G.

(2002). Necrosis of Nasal and Airway Epithelium in

Rats Inhaling Vapors of Artificial Butter Flavoring.

Toxicology and Applied Pharmacology, 185:128-135.

Kreiss, K. (2002). Personal correspondence with Dr.

Kay Kreiss, Division of Respiratory Disease Studies,

National Institute of Occupational Safety and Health

(NIOSH), Morgantown, WV, November 26, 2002.

Kreiss, K., Gomaa, A., Kullman, G., Fedan, K.,

Simoes, E., Enright, P. (2002). Clinical Bronchiolitis

Obliterans in Workers at a Microwave-Popcorn Plant.

N. Engl. J. Med., 347:330-338.

Kullman, G. (2002). Personal correspondence with Dr.

Greg Kullman, Division of Respiratory Disease

Studies, National Institute of Occupational Safety and

Health (NIOSH), Morgantown, WV, December 2,

2002.

Kullman, G., Boylstein, R., Piacitelli, C., Jones, W.,

Pendergrass, S., Hubbs, A., and Kreiss, K. (2002).

Respiratory Exposures from Microwave Popcorn

Packaging (Abstract), AIHce Conference, June 2002.

Parmet, A.J., and Von Essen, S. (2002). Rapidly

Progressive, Fixed Airway Obstructive Disease in

Popcorn Workers: A New Occupational Pulmonary

Illness? J Occup. Environ. Med., 44:216-218.

Simoes, E., Phillips, P., Maley, R., Kreiss, K., Malone,

J., and Kanwal, R. (2002a). Fixed Obstructive Lung

Disease in Workers at Microwave Popcorn Factory –

Missouri, 2000-2002. JAMA, 287:2939-2940.

Simoes, E., Phillips, P., Maley, R., Kreiss, K., Malone,

J., and Kanwal, R. (2002b). Fixed Obstructive Lung

Disease in Workers at Microwave Popcorn Factory –

Missouri, 2000-2002. MMWR, 51:345-347.

EVALUATION OF COATINGS TOMINIMIZE POTENTIAL

DERMAL EXPOSURE TO ARSENIC ON PRESSURE

TREATED WOOD (CCA)

In collaboration with EPA’s Office of Pesticide Policy

and the Consumer Product Safety Commission, IEMB

is evaluating the ability of selected coatings to reduce

the amount of arsenic that can be wiped from the

surfaces of CCA (Chromated copper arsenate) treated

wood. CCA is a chemical wood preservative injected

under high pressures to protect wood from decay and

insect damage. The manufacturers of CCA treated

wood have asked EPA to remove registration of this

product for residential use, including playground

equipment, decks, and landscape timbers, and they

intend total conversion to alternative treatments by

December 31, 2003. However, there remains extensive

potential for dermal contact with arsenic residues on

treated surfaces, and the potential is greatest for the

most susceptible subpopulation, infants and small

children, due to their close contact with surfaces and

hand to mouth activities. A recent field survey of CCA

treated surfaces indicates that widely used deck sealants

are often not effective at preventing arsenic

contamination of surfaces beyond six months. The

purpose of this project is to evaluate performance for

several deck sealants and stains. The project will also

evaluate a limited number of encapsulants and film

forming finishes. The information generated by this

project will assist the public in determining how to

reduce exposure to arsenic and provide the coatings

industry with a methodology that they can use to

evaluate the ability of their products to prevent dermal

exposure from CCA treated wood. 

Selected products will be applied to “mini-decks”

constructed from CCA treated deck boards recovered

from two decks, an older deck that received

considerable use over several years serving as an

outdoor extension of a cafeteria, and a much newer deck

(approximately 2 years old) that was located outside but

(Continued on Page 7)
Inside IAQ, Spring/Summer 2003 Page 7

never placed into active service. Once the mini-decks

have been assembled, they will be prepared for coating

by a standard protocol. Only one coating will be

applied to each mini-deck to minimize the potential for

cross contamination. The mini-decks will receive fullsun exposure in a natural, out-of-doors setting.

Periodically, as the mini-decks weather and age, we

will determine the amount of arsenic, chromium, and

copper that can be wiped from the surfaces of the deck

boards. Sampling may continue for up to two years

and will provide insight into initial and longer-term

ability of various coatings to reduce arsenic that may

be wiped from the surface of the CCA treated deck

boards. (Mark A. Mason 919 541-4835,

mason.mark@epa.gov).

SUMMARIES OF RECENT PUBLICATIONS

Microbial Volatile Organic

Compound Emission Rates and

Exposure Model - This paper

presents the results from a study

that examined microbial volatile

organic compound (MVOC)

emissions from six fungi and one

bacterial species (Streptomyces

spp.) commonly found in indoor

environments. Data are presented

on peak emission rates from

inoculated agar platesloaded with

surface growth, ranging from

33.5 μg per m2 per 24 hours

(Cladosporiumsphaerospermum)

to 515 μg per m2

 per 24 hours

(Rhodo torula glutinis).

Furthermore, changes in MVOC

emission levels over the growth

cycle of two o f t h e

microorganisms are examined.

This report also includes a

calculation of the impact of

MVOC emissions on indoor air

quality in a typical house and an

application of an exposure model

used in a typical school

environment. Source: Indoor Built

Environment, Vol. 11, pp. 208-213, 2002.

(EPA Contact: Marc M enetrez, 919-541-

7981, menetrez.marc@epa.gov)

Characterization and Reduction of

Formaldehyde Emissions from a

Low-VOC Latex Paint - The patterns

of formaldehyde emission from a low

volatile organic compound (VOC)

latex paint applied to gypsum board

were measured and analyzed by small

environmental chamber tests. It was

found that the formaldehyde

emissions resulted in sharp increase

of chamber air formaldehyde

concentration to a peak followed by

transition to a long-term slow decay.

A first-order decay in-series model

was developed to interpret the

chamber data. The model

characterized the formaldehyde

emissions from the paint in three

stages; an initial puff of instant

release, a fast decay, and a final stage

of slow decay controlled by a

solid-phase diffusion process that can

last for more than a month. The model

was also used to estimate the peak

concentration and the amount of

formaldehyde emitted during each

stage. The formaldehyde sources

were investigated by comparing

emission patterns and modeling

outcomes of different paint

formulations. The biocide used to

preserve the paint was found to be a

major source of the formaldehyde.

Chamber test results demonstrated

that replacing the preservative with

a different biocide for the particular

paint tested resulted in an

approximately 55% reduction of

formaldehyde emissions, but the

reduction affected only the

third-stage long-term emissions.

Source: Indoor Air,Vol. 12, No. 1, pp. 10-

16, 2002. (EPA Contact: John Chang,

919-541-3747, chang.john@epa.gov)

Review of Indoor Emission Source

Models-Part 1. Overview - Indoor

emission source models are mainly

used as a component in indoor air

quality (IAQ) and exposure

modeling. They are also widely
Inside IAQ, Spring/Summer 2003 Page 8

used to interpret the experimental

data obtained fromenvironmental

chambers and buildings. This

paper compiles 46 indoor

emission source models found in

the literature. They represent the

achievements that IAQ modelers

have made in recent years in

modeling indoor sources. While

most models have a certain

degree of usefulness, genuine

predictive models are still few,

and there is undoubtedly much

room for improvement. This

review consists of two sections.

Part 1 - this paper - gives an

overview of the 46 models,

briefly discussing their validity,

usefulness, limitations, and flaws

(if any). Part 2 focuses on

parameter estimation, a topic that

is critically important to modelers

but has not been systematically

discussed. Source: Environmental

Polution, Vol. 120, No. 3, pp. 533-549,

2002. (EPA Contact: Zhishi Guo, 919-

541-0185, guo.zhishi@epa.gov)

Review of Indoor Emission

Source Models: Part 2.

Parameter Estimation - This

review consists of two sections.

Part 1 provides an overview of 46

indoor emission source models.

Part 2 (this paper) focuses on

parameter estimation, a topic that

is critical to modelers but has

never been systematically

discussed. A perfectly valid

model may not be a useful one if

its parameters are difficult to

estimate in the absence of

experimental data. This is true for

both statistical and mass transfer

models.Thirty-seven methods are

compiled and reviewed in this

paper. Overall, developing

methods for parameter estimation

has fallen far behind developing the

models. Such imbalance is the main

reason that many models have been

left on the shelf since they were

published. Source: Environmenta l

Polution, Vol. 120, No. 3, pp. 551-564,

2002. (EPA Contact: Zhishi Guo, 919-541-

0185, guo.zhishi@epa.gov)

Testing Antimicrobial Efficacy on

Porous Materials - The efficacy of

antimicrobial treatments to eliminate

or control biological growth in the

indoor environment can easily be

tested on nonporous surfaces.

However, the testing of antimicrobial

efficacy on porous surfaces, such as

those found in the indoor environment

[i.e., gypsum board, heating,

ventilating, and air-conditioning

(HVAC) duct-liner insulation, and

wood products] can be more

complicated and prone to incorrect

conclusions regarding residual

organisms and nonviable allergens.

Research to control biological growth

using three separate antimicrobial

encapsulants on contaminated ductliner insulation has been performed in

both field and laboratory testing. The

results indicate differences in

antimicrobial efficacy for the period

of testing. Source: Indoor Built

Environment, Vol. 11, pp. 202-207, 2002.

(EPA Contact: Marc Menetrez, 919-541-

7981, menetrez.marc@epa.gov)

Evaluating the Potential Efficacy of

Three Antifungal Sealants of Duct

Liner and Galvanized Steel as Used in

HVAC S y stems - Curren t

recommendations for remediation of

fiberglassduct materials contaminated

with fungi specify complete removal,

which can be extremely expensive,

but in-place duct cleaning may not

provide adequate protection from

regrowth of fungal contamination.

Therefore, a common practice in the

duct-cleaning industry is the

postcleaning use of antifungal

surface coatings with the

implication that they may contain or

limit regrowth. However, even the

proper use of these products has

generally been discouraged because

little research has been conducted

on the effectiveness of most

products as used in heating,

ventilating, and air-conditioning

(HVAC) systems. Three different

coatings were evaluated on

fiberglass duct liner (FGDL). Two

of the three coatings were able to

limit growth in the 3-month study;

the third did not. One of the

coatings that was able to limit

growth was further evaluated in a

comparison of FGDL or galvanized

steel (GS) under conditions that

mimicked their use in HVAC

systems. The results showed that

both moderately soiled and heavily

soiled uncoated FGDL and GS duct

material can support fungal growth,

but that GS duct material was more

readily cleaned. The use of an

antifungal coating helped limit, but

did not fully contain, regrowth on

FGDL. No regrowth was detected

on the coated GS. Source: J. Ind

Microbiol Biotechnol, Vol. 29, No. 1, pp.

38-43, 2002. (EPA Contact:M arc

Menet rez ,919-541-7981 ,

menetrez.marc@epa.gov)

An Analytical Method for the

Measurement of Nonviable

Bioaerosols - Exposures from indoor

environments are a major issue for

evaluating total long-term personal

exposures to the fine fraction (<2.5

μm in aerodynamic diameter) of

particulate matter (PM). It is

widely accepted in the indoor air
Inside IAQ, Spring/Summer 2003 Page 9

qualit y (IAQ) research

communitythat biocontamination

is one of the important indoor air

pollutants. Major indoor air

biocontaminants include mold,

bacteria, dust mites, and other

antigens. Once th e

biocontaminants or their

metabolites become airborne,

IAQ could be significantly

deteriorated. The airborne

biocontaminants or their

met abolites can induce

irritational, allergic, infectious,

and chemical responses in

exposed individ ual s .

Biocontaminants such as some

mold spores or pollen grains,

because of their size and mass,

settle rapidly within the indoor

environment. Over time they

may become non-viable and

fragmented by the process of

desiccation. Desiccated nonviable fragments of organisms are

common and can be toxic or

allergenic, depending upon the

specific organism or organism

component. Once these smaller

and lighter fragments of

biological PM become suspended

in air, they will have a greater

tendency to stay suspended.

Although some bioaerosols have

been identified, few have been

quantitatively studied for their

prevalence within the total indoor

PM with time, or their affinity to

penetrate indoors.

This paper describes a

preliminary research effort to

develop a methodology for the

measurement of non-viable

biologically based PM, analyzing

for mold, ragweed antigens, and

endotoxins. The research objectives

include 1) develop a set of analytical

methods and compare impactor media

and sample size, and 2) quantify the

relationship between outdoor and

indoor levels of bioaerosols. Indoor

and outdoor air samples were passed

through an Andersen Non-Viable

cascade impactor in which particles

from 0.2 to 9.0 μm were collected and

analyzed. The presence of mold,

ragweed, and endotoxin was found in

all 8 size ranges. The presence of

respirable particles of mold and pollen

found in the fine particle size range

from 0.2 to 5.25 μm is evidence of

fragmentation of larger source

particles that are known allergens.

Source: J. Air & Waste Management

Association, Vol. 51, pp. 1436-1442, 2001.

(EPA Contact: Marc Menetrez,919-541-

7981, menetrez.marc@epa.gov)

Lead in Candle Emissions – The

purpose of this work was to

investigate the local prevalence of

lead-wick candles, to measure their air

lead (PbA) emission rates, to

investigate the partition of lead

between air and ashes, to assess a lead

mass balance, and to model

concentration, exposure, and

deposition for realistic scenarios. We

also investigated a definitive

association between respirable

particulate and lead. This question is

important because of the potential risk

to human health represented by the

some $1 to $2 billion worth of candles

sold in the United States annually.

Assuming $5/candle, this sales figure

represents an average of about 300

million candles. If even 1% have lead

in the core of the wick, at least 3

million candles are potential lead

emitters. Depending upon the

amount of candle burning activity,

the number burning simultaneously,

and indoor room conditions, lead

concentrations in excess of both

environmental and occupational

standards could occur. While the

primary danger is from inhalation,

the deposition of lead-bearing fine

particulate in household dust

provides a secondary exposure

route for babies and toddlers due to

their ubiquitous hand-to-mouth

behavior. To define the problem,

100 sets of candles (two or more

identical candles) were purchased

locally. The criterion for purchase

was that the candles must appear to

contain a metal-cored wick or be

covered by a metallic pigment. Of

the candles purchased, 8%

contained lead wicks. The wicks

were 39 to 74% lead (remainder,

fabric or paper), and the lead cores

(approximately 100% lead) had

linear densities of 13 to 27 mg/cm.

Candles were burned to completion

in a closed chamber to capture the

air emissions, and the candle

residue was extracted to assess the

lead mass balance. It was found that

individual candles emitted lead to

the air at average rates that ranged

from 100 to 1700 :g/hr. Assuming

realistic indoor conditions, these

emission rates were modeled to

project room air concentration,

child exposure by inhalation, and

indoor deposition. Results showed

that burning single candles can

easily raise the source room

concentration above the ambient air

lead concentration limit of 1.5

:g/m3

 set by EPA . Burning

multiple candles can elevate it
Inside IAQ, Spring/Summer 2003 Page 10

above OSHA permissible

exposure limits of 50:g/m

3

.

Although blood lead levels have

dropped precipitously in the

United States since lead was

phased out of gasoline in 1986,

nearly 900,000 children still had

levels above 10 :g/dL during

NHANES III. Considering

candle sales in the United States

and that children may spend as

much as 88% of their time

indoors, it is reasonable to

suspect that some blood lead

elevation in children arises from

indoor microenvironments where

lead-wick candles are burned. In a response to the problem, the U.

S. Consumer Product Safety

Commission issued a rule in April, 2003, banning candles with

lead wicks. Source: The Science of

the Total Environment, Vol. 296,

Issues 1 - 3, 159-174, 2002. (EPA

Contact: Shirley Wasson, 919-541-

1439, wasson.shirley@epa.gov)

Analysis of Lead in Candle Particulate Emissions by XRF

Using UniQuant® 4 - As part of

an extensive program to study the

small combustion sources of

indoor fine particulate matter

(PM), candles with lead-core

wicks were burned in a 46-L

glass flow-through chamber. The

particulate emissions with

aerodynamic diameters <10 :m

(PM10) were captured on quartz

filters and analyzed under

vacuum in a Philips PW 2404

wavelength-dispersive X-Ray

Fluorescence (WDXR F)

Spectrometer. UniQuant

®

 4

software was used to calculate the

filter lead concentrations. Particulate

filterloading masses ranged from 0.18

to 52.1 mg. The lead concentrations

ranged from 0.2 to 80% by weight,

with carbon comprising the remainder

of the matrix. The method was

validated by analyzing 87 filters, first

by XRF and then by EPA Method 12

atomic absorption spectroscopy

(AAS). For 84 filters, the average

particle mass recovery after XRF

analysis was 99±6%. For 84 filters

analyzed for lead by both methods,

the average recovery of lead by XRF

compared to the AAS analysis was

108±9%. Modeling of candle

emissions using typical room

ventilation scenariosshowed that even

low-emitting candles can produce a

lead concentration above the EPA

National Ambient Air Quality

Standard (NAAQS) of 1.5 :g/m

3

(quarterly average). Burning more

than one heavily emitting candle in a

poorly ventilated space can produce

concentrations exceeding the

Occupational Safety and Health

Administration (OSHA) Permissible

Exposure Limit (PEL) concentration

of 50 :g/m

3

 (8-hour time-weighted

average). Source: Advances in X-Ray

Analysis, Vol. 45, 539-543, 2002. (EPA

Contact: Shirley Wasson, 919-541-1439,

wasson.shirley@epa.gov)
Inside IAQ, Spring/Summer 2003 Page 11

NEWS FROM NERL

STUDYING THE INFLUENCE OF AMBIENT

PARTICULATE MATTER ON INDOOR

CONCENTRATIONS: FIELD STUDIES OF

SENSITIVE POPULATIONS

Although scientists know that particulate matter (PM)

affects human health, we need to know more about the

sources of PM, how people come in contact with it, and

how levels of PM outdoorsinfluencePM concentrations

indoors. 

EPA's National Exposure Research Laboratory (NERL)

recently completed three longitudinalPMexposure field

studies. These studies were conducted in Baltimore,

Maryland (1998), Fresno, California (1999), and

Research Triangle Park (RTP), North Carolina (2000-

2001) and were designed to evaluate factors that

influence the contribution of ambient PM to residential

indoor PM concentrations. The studies addressed

selected non-smoking sub-populations that might be

sensitive to potential exposures to ambient PM: the

elderly, hypertensive, and cardiac impaired. Different

geographical settings, seasons, and housing types were

included. The Baltimore and Fresno measurements

were conducted in retirement facilities; the RTP study

was conducted in 38 single-family homes.

The studies were of sufficient duration (28 days) and

size (20-60 participants) to investigate both longitudinal

and cross-sectional correlations between personal,

residential indoor, residential outdoor, and ambient PM

measurements. Residential measurements of PM2.5,

PM10, and PM10-2.5 were routinely collected.

Additional pollutants were also collected in some of the

studies. In addition, detailed questionnaires were used

to gather information on daily household activities and

other factors that might influence particle infiltration. 

Results from these three field studies showed mean

indoor/outdoor PM2.5 mass concentration ratios

ranging from 0.49 to 1.12 :g/m3. The single-family

home data from the RTP study provided the opportunity

for a more detailed examination of select particle

infiltration issues. These results showed a wide range

in the magnitude and variabilityofindividual residential

indoor PM2.5 24-hour average PM mass concentrations

(4 to 119 ) over the course of one year. The mean least

squares estimate of individual residences PM2.5

ambient particle infiltration rates (Finf) was 0.42 ± 0.38,

indicating the high degree of infiltration variability in

the RTP homes.

For more information, contact Ron Williams,

ORD/NERL, 919-541-2957 ( williams.ron@epa.gov).
Inside IAQ, Spring/Summer 2003 Page 12

GLOSSARY

ACH - Air Change per Hour MEKO - Methyl Ethyl Ketoxime

AHU - Air Handling Unit NERL - National Exposure Researchg

CFU - Colony Forming Unit Laboratory

DMTC - Dynamic Microbial Test Chamber NRMRL - National Risk Management

FDL - Fiberglass Duct Liner Research Laboratory

FGD - Fiberglass Ductboard P2 - Pollution Prevention

GC/MS - Gas Chromatography/Mass Spectrography RH - Relative Humidity

HEPA - High Efficiency Particulate Air STKi - Simulation Tool Kit for IAQ

IAQ - Indoor Air Quality and exposure

IEMB - Indoor Environment Management Branch TVOC - Total Volatile Organic 

 Compound

VOC - Volatile Organic Compound
United States

Environmental Protection Agency

National Risk Management Research Laboratory

Indoor Environment Management Branch

MD E305-03

Research Triangle Park, NC 27711

Official Business

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