United States Environmental
Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
EPA-600/N-03/005 Spring/Summer 2003
SEFA
Inside I A Q
EPA's Indoor Air Quality Research Update
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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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 fromPolluted 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
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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 at www.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,
ggarbowskv@awma. org. For further information on the
technical program, contact Jim letter at (919) 541-4830,
ietter.jim@epa.gov.
ESTIMATION OF OVERALL MASS TRANSFER
COEFFICIENT FOR VOC EMISSIONS FROM
AQUEOUS SOLUTIONS
The ability to 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):
Figure 1 EPA's new "green" research facilities
KOG = overall gas-phase mass transfer coefficient (m/h),
CL = pollutant concentration in liquid (|_ig/m3),
CG = pollutant concentration in air (|j,g/m3), and
H = dimensionless Henry's constant [(|j,g/m3)air/
The two overall masstransfer coefficients, KOL andKOG,
are defined by Eqs. 3 and 4, respectively:
1
1
1
K.
OL
(3)
(4)
R=SKOL(CL-Ca/H)
R = S KOG (Cj. H- CG)
where:
(1)
(2)
R = emission rate (|ig/h),
S = source area (m2),
KOL = overall liquid-phase mass transfer coefficient
(m/h),
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
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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 3.33x10"7 to 3.67X10~3 (atm
m3/mol). The estimated overall liquid-phase mass
transfer coefficients for still solutions varied from
1.8 x 10"6 to 5.7 x 1O"3 m/h; the estimated liquid-phase mass
transfer coefficients were 9.78X10~3 m/h for the
reference compound (oxygen) and 5.00X 10~3 to 6.04x 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.
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 (1IKOL or 1 /KOL). Using the results of
this work, Figure 3 illustrates the contribution of the
gas-phase mass transfer resistance \I(H kg) to \IKOL as
a function of H and kg. For still water under typical
indoor environmental conditions, we suggest that KOL 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.
e
HO
Figure 2. Comparison between experimental and
calculated overall liquid-phase mass transfer
coefficients. The solid line represents linearity.
(6)
where:
= 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,
- kg » 10mfl"i E
Figure 3. Contribution of the gas-phase mass
transfer resistance (GMTR) to the overall mass
transfer resistance (l/KOL). The curves from left to
right are for k„ = 10, 5, 2, and 1 m/h, respectively.
Inside IAQ, Spring/Summer 2003
PageS
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BIOLAB BEGINS OPERATION
The BioLab (BL) is a component of the Indoor
Environment Management Branch of APP CD/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 /Cycler for
amplifying DNA and RNA fragments using RT-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\
APPCDYFacility 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.timothv(a),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. ep a. gov//app cdwww/crb/
Inside IAQ, Spring/Summer 2003
Page 4
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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 (Rreiss 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 permissible exposure 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
NIO SH 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
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Inside IAQ, Spring/Summer 2003
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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, IS., 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? JOccup. 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 TO MINIMIZE 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
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Inside IAQ, Spring/Summer 2003
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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 full-
sun 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 plates loaded with
surface growth, ranging from
33.5 ug per m2 per 24 hours
(Cladosporium sphaerospermum)
to 515 ug per m2 per 24 hours
(Rhodotorula glutinis).
Furthermore, changes in MVOC
emission levels over the growth
cycle of two of the
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 Menetrez, 919-541-
7981, menetrez.marc(Sjepa.gov)
Characterization and Reduction of
Formaldehyde Emissions from a
Low-VOCLatex 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. l,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 7
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used to interpret the experimental
data obtained from environmental
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(giepa.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: Environmental
Polution, Vol. 120, No. 3, pp. 551-564,
2002. (EPA Contact: Zhishi Guo, 919-541-
0185, guo.zhishitajepa.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 duct-
liner 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.marci@epa.gov)
Evaluating the Potential Efficacy of
Three Antifungal Sealants of Duct
Liner and Galvanized Steel as Used in
HVAC Systems - Current
recommendations for remediation of
fiberglass duct 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. l,pp.
38-43, 2002. (EPA Contact:Marc
Menetrez, 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
um in aerodynamic diameter) of
particulate matter (PM). It is
widely accepted in the indoor air
Inside IAQ, Spring/Summer 2003
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quality (IAQ) research
community that biocontamination
is one of the important indoor air
pollutants. Major indoor air
biocontaminants include mold,
bacteria, dust mites, and other
antigens. Once the
biocontaminants or their
metabolites become airborne,
IAQ could be significantly
deteriorated. The airborne
biocontaminants or their
metabolites can induce
irritational, allergic, infectious,
and chemical responses in
exposed individuals.
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 non-
viable 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 um 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 um 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 |-ig/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
ug/m3 set by EPA . Burning
multiple candles can elevate it
Inside IAQ, Spring/Summer 2003
Page 9
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above OSHA permissible
exposure limits of 50 |-ig/m3.
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 i-ig/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 UniQuanf 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 |_im
(PM10) were captured on quartz
filters and analyzed under
vacuum in a Philips PW 2404
wavelength-dispersive X-Ray
Fluorescence (WDXRF)
Spectrometer. UniQuant® 4
software was used to calculate the
filter lead concentrations. Particulate
filter loading 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 scenarios showed that even
low-emitting candles can produce a
lead concentration above the EPA
National Ambient Air Quality
Standard (NAAQS) of 1.5 ng/m3
(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 |-ig/m3 (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 10
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NEWS FROM NERL
STUDYING THE INFLUENCE OF AMBIENT
PARTICULATE MATTER ON INDOOR
CONCENTRATIONS: FIELD STUDIES OF
SENSITIVE POPULATIONS
Although scientists know that paniculate 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 outdoors influence PM concentrations
indoors.
for a more detailed examination of select particle
infiltration issues. These results showed a wide range
in the magnitude and variability of individual 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).
EPA's National Exposure Research Laboratory (NERL)
recently completed three longitudinal PM exposure 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 |j,g/m3. The single-family
home data from the RTP study provided the opportunity
Inside IAQ, Spring/Summer 2003
Page 11
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GLOSSARY
ACH - Air Change per Hour MEKO - Methyl Ethyl Ketoxime
AHU - Air Handling Unit NERL - National Exposure Researchg
CPU - 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
Inside IAQ, Spring/Summer 2003 Page 12
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United States
Environmental Protection Agency
National Risk Management Research Laboratory
Indoor Environment Management Branch
MD £305-03
Research Triangle Park, NC 27711
Official Business
Penalty for Private Use
$300
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