United States Environmental
Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
EPA/600/N-01/002 Spring/Summer 2001
Inside I A Q
EPA's Indoor Air Quality Research Update
We are pleased to be able to resume semiannual
publication of Inside IAQ after an unavoidable 2-year
suspension. This issue is being distributed via first class
mail using our most recent mailing list; in addition,
copies of this and previous editions of the newsletter
are available on the internet at:
www.epa.gov/appcdwww/crb/iemb/insideiaq.htm
In This Issue
Page
Testing Demonstrates that Nominally Identical
Photocopier Toners Can Have Significantly Different
VOC Emissions
Identification of Hazardous Air Pollutants
Emitted from a Shower Curtain
A Pilot Home Asthma Intervention Study
In Boston Public Housing
Candle Burning as a Potential Source of
Indoor Air Pollution
The Impact of Ozone on Indoor Air Quality 5
TESTING DEMONSTRATES THAT NOMINALLY IDENTICAL PHOTOCOPIER TONERS CAN HAVE
SIGNIFICANTLY DIFFERENT VOC EMISSIONS
A laboratory study has been completed on a series of
nominally identical toners, manufactured for use in a specific
dry-process photocopier. The objective was to determine the
extent to which the emissions of volatile organic compounds
(VOCs) from a given toner might be reduced through
judicious selection of the process and the polymer feedstock
used in the manufacture of that toner.
A cooperating toner manufacturer produced four nominally
identical batches of toner for a selected copier, according to
a 2x2 matrix: using two different manufacturing processes
(vented and unvented extrusion); and using two different lots
of polymer feedstock, to be fed to the extruder. The
manufacturer also provided samples of the two unprocessed
feedstocks. In addition to these manufacturer samples, toner
cartridges for this same copier were purchased from two
local retailers, representing three different toner lots. The
manufacturer, manufacturing process, and feedstock
characteristics for these retailer toners were unknown.
These toners were tested using a flow-through thermal
desorption test method, developed for this project. In this
method, toner samples were ballistically heated to the
temperature range of the copier (180 to 200 °C), and the
VOCs driven off were captured on Tenax® sorbent. These
Tenax® cartridges were then desorbed and analyzed using
gas chromatography (GC) with a flame ionization detector
(FID), calibrated for up to 21 selected individual VOCs.
Statistical analysis of the results from the manufacturer
samples showed that (p < 0.05):
• The manufacturing process (vented vs. unvented
extrusion) had no effect on toner emissions in this
study. That is almost certanly because only a
negligible vacuum (2 Pa below atmospheric) was
applied in producing the vented toners available for
this study; a vacuum perhaps 4 orders of magnitude
greater would have been required for effective
removal of VOCs.
Inside IAQ, Spring/Summer 2001
Page 1
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• The feedstock had little or no effect on the emissions
from the toners because there was no difference in
the emissions between the two feedstocks used in
this study.
Each unprocessed feedstock generally has 15 to
30% higher emissions of ethylbenzene, p-xylene, and
styrene, compared to the toners manufactured using
that feedstock. This observation would be consistent
with the thesis that some fraction of these
compounds - present as impurities in the feedstock
- is driven off during the extrusion process.
Each unprocessed feedstock consistently has about
30 to 60% lower emissions of benzaldehyde and
acetophenone, compared to the toners manufactured
using that feedstock. These observations would be
consistent with the thesis that some amount of these
oxygenated compounds is created by thermal-
oxidative degradation of the polymer during the
extrusion process.
Statistical analysis of the results from the retailer toners
showed that (p < 0.05):
All of the retailer toners have emissions of
ethylbenzene, xylenes, styrene, and acetophenone
that are significantly lower (by 15 to 100%) than
those from the manufacturer toners (with either
feedstock).
All of the retailer toners have emissions of
benzaldehyde that are significantly higher (by 125 to
350%) than those from the manufacturer toners.
In general, the total VOC (TVOC) emissions from
the retailer toners are statistically the same as those
from the manufacturer toners, even though the
emissions of individual compounds can vary
significantly.
In general, there is no statistical difference in
emissions between the retailer toners, within the
statistical power of this analysis (two samples per
toner).
Overall, the conclusions from this study are:
1. From comparison of the manufacturer and retailer
toners tested here, it is clear that nominally identical toners -
manufactured to meet the fuser specifications for a single
photocopier - can have significantly different emissions of
individual VOCs when heated in the laboratory. Emissions
of a given compound can vary by a factor of 2 or more
between toners.
2. Even significant differences in emissions of individual
VOCs between toners might not indicate one as a clearly
preferable low-emitting product. Comparison of the
manufacturer and retailer toners indicates that - while the
retailer toners had much lower emissions of some
compounds (ethylbenzene, xylenes, styrene, acetophenone)
- they had higher emissions of other compounds
(benzaldehyde, phenol). (All of these compounds, except
benzaldehyde, are Hazardous Air Pollutants.) The
difference in TVOC emissions between the two toner sets is
modest at best, and often not statistically significant.
3. The differences in emissions between the
manufacturer and retailer toners are almost certainly due to
differences between the manufacturing processes and/or the
feedstock polymers used in the two cases. But without
information on the retailer process(es) and feedstocks, the
specific factors creating the differences could not be
identified in this study.
4. Because the specific factors creating the emission
differences between the manufacturer and retailer toners
cannot be identified, it is not possible from this study to make
specific recommendations regarding how process or
feedstock might be modified in order to produce lower-
emitting toners for a given copier.
5. The tests on the manufacturer toners showed that
vented extrusion did not produce toners having lower
emissions than did unvented extrusion; but this result was
almost certainly obtained because only a negligible vacuum
(2 Pa) was applied during vented extrusion. These tests also
showed that the feedstock had only modest, if any, impact
on toner emissions; but the feedstocks were almost identical,
creating this result.
6. The tests on the manufacturer toners and feedstocks
demonstrated that essentially all of the compounds observed
in the toner emissions result, at least in part, from impurities
that are present in the feedstocks to begin with. The tests
also demonstrated that the concentrations of some species
can be increased during the extrusion process, presumably by
oxidative degradation of the polymer. These observations
can be used to postulate explanations for the differences in
emissions between the manufacturer and retailer toners.
(EPA Contact: Bruce Henschel, 919-541-4112,
henschel.brucefSiepa.gov)
Inside IAQ, Spring/Summer 2001
Page 2
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IDENTIFICATION OF HAZARDOUS AIR POLLUTANTS EMITTED FROM A SHOWER CURTAIN
A single soft vinyl shower curtain was tested. The 70 by 72-
inch shower curtain was 100% vinyl, manufactured in China
for a large U.S. retailer. The product was purchased at a
local retail outlet. The shower curtain was colored, primarily
blue. It had a strong "plastic" odor when removed from the
package.
Equilibrium headspace was analyzed using a newly
developed static chamber test method. The test was
performed by placing samples of the shower curtain in a 53-
L stainless steel chamber. After loading the shower curtain
samples, the chamber was sealed and placed in an incubator
set at 23°C. The tests were static with no air flow to the
chamber. Special racks were constructed to suspend the
shower curtain in the chamber to maximize the exposed
surface area and accelerate the experiments. The racks
consist of a frame with stainless steel bars on the top and
bottom spaced approximately 2 cm apart. The shower
curtain was cut into strips with nominal width of 34.3 cm and
the strips were woven through the bars.
Headspace chamber air samples were collected on Tenax
sorbent tubes using a sampling pump. The samples were
analyzed by thermal desorption interfaced to a gas
chromatograph equipped with a flame ionization detector.
Figure 1 is a chromatogram of the headspace sample taken
at the 168th h. Among the 14 compounds identified, methyl
alcohol (methanol), methylene chloride, toluene, and phenol
were classified as hazardous air pollutants by the 1990 Clean
Air Act Amendments. (EPA Contact: John Chang, 919-541-
3747, chang.john(g),epa. gov)
Figure 1. Chromatogram identifying hazardous
compounds.
Peak ID
A
B
C
D
F
G
H
I
J
K
L
M
Compound
Methanol
Bthanol
TnoJiloromonofluorDmethmie
Methylsne chloride
Toluene
6-Methyl-l -actene
Phenol
2,2-Dimethyl deoans
2-Elhyl-l-hBxanal
Uideoane
Dodsoans
Hexadeoane
A PILOT HOME ASTHMA INTERVENTION STUDY IN BOSTON PUBLIC HOUSING
A small study was recently completed to investigate the
feasibility of implementing asthmagen reduction measures in
Boston Public Housing. The study is a community/
university/government collaboration between the Tufts
University School of Medicine, the Harvard University
School of Public Health, the Committee for Boston Public
Housing, the Tenant Task Force of the Franklin Hill Housing
Development (Figure 2), Boston Medical Center, and the
U.S. Environmental Protection Agency's Office of Research
and Development and Region 1. The goal of the program
was to reduce household environmental factors, such as
allergens, airborne particles, and irritant gases, that contribute
to the exacerbation of asthma symptoms. The program was
designed to carry out interventions in a manner that
maximized participation from both community organizations
and individual tenants involved in the study. This was a pilot-
scale study, intended primarily to gain experience working in
the public housing arena in order to develop hypotheses and
methods for future research projects.
Nine families with asthmatic children living in Franklin Hill
Housing Development in Boston were enrolled in the asthma
intervention program. At the beginning of the study, the
asthmatic children were evaluated by a pediatric
pulmonologist. The evaluation included administration of a
symptom frequency questionnaire, review of medication use,
and physical examination. A computerized
pneumotachometer (MultiSpiro) was used to perform
pulmonary function testing on all children over 4 years of
age. Allergy skin testing was performed for cat, mouse, dog,
cockroach, and dust mite antigens. Over the course of the
study, the participants kept a diary of asthma symptoms and
medication use.
Asthmagen-r eduction Interventions
Interventions started with thorough cleaning of the
apartments and furniture, using a machine that applied an
atomized water-based solution at 200 psi, which was
extracted to leave little moisture in fabric, upholstery, and
Inside IAQ, Spring/Summer 2001
Page 3
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carpeting. In addition, cracks and crevices that might allow
pest entry were sealed, and pest repellant devices were
installed in some apartments. In many cases, exposed steam
piping was present, resulting in high indoor temperatures and
burn hazards. This was insulated. Mattresses and pillows on
the children's beds, and any other beds the children slept on,
were encased in dust-mite-proof covers. Some tenants were
provided with high-efficiency particulate air (HEPA)-filtered
vacuum cleaners for their own use. Some apartments were
equipped with air filtration systems: electrostatic filters,
HEPA filters, or a modified clean-room system containing a
HEPA filter and an ozone lamp, followed by an activated
charcoal filter. The filter systems were maintained by
project staff. The specific intervention used for each
apartment was tailored to „. - „ ... TT... .
, , , Figure 2. Franklin Hill Apartments
the conditions in that
apartment.
Data Collection
In-depth qualitative and
quantitative information
was collected from these
nine apartments and their
residents. The qualitative
information included
asthma symptom diaries
and resident responses in
focus group discussions
both before and after the
interventions were
implemented. This
provided valuable insight
into the institutional, social,
economic, and personal factors that affect the use of asthma
prevention interventions in public housing. Quantitative data,
from intensive environmental monitoring, was collected to
thoroughly characterize the state of the nine public housing
apartments, and to cull hypotheses about the effectiveness of
the interventions.
Monthly monitoring visits were made to each apartment.
During these visits, the study team made a visual inspection
for mold, wetness, cockroaches, rodent droppings, etc.
Temperature and relative humidity were measured. Inhalable
and respirable particulate matter-with aerodynamic
diameters of < 10 Cm (PM10) and < 2.5 Om (PM25),
respectively- were collected on 37 mm Teflon 2 Cm-pore
filters. Twenty- four hour, time-integrated passive nitrogen
dioxide (N02) samples were taken using Yanagisawa
Badges and analyzed by light spectrometry. Twenty-four
hour VOC samples were collected passively on thermal
desorption tubes packed with Carbotrap B, and analyzed by
gas chromatography/mass spectroscopy (GC/MS).
Dust samples were collected on cellulose extraction thimbles
(Whatman Inc., Hillsboro, OR) using a small, portable
vacuum cleaner (Eureka Mighty Mite). Composite samples
were taken from asthmatic children's bedrooms by
vacuuming the children's bedding and the carpeting around
the beds . These were analyzed for dust mite antigens, Der
p 1 and Der f 1; cat antigen, Pel d 1; dog antigen, Can f 1;
fungi; and endotoxin.
Other samples were
collected from the seats
and carpeting of the
apartments' main living
areas, and analyzed for
dust mite antigens, Der
p 1 and Der f 1; cat
antigen, Pel d 1; fungi;
and dog antigen, Can f
1. A third set of
samples was collected
from kitchen cabinets
and analyzed for rodent
antigen, Mus m 1; and
cockroach antigen, Bla
g 1. Dust was also
analyzed for viable
fungus by plating onto
malt extract agar. Endotoxin, and dust mite, cat, dog, roach,
and mouse antigens were measured using a
spectrophotometric Enzyme-Linked-Immunosorbent-Assay
(ELISA) method.
Current Progress
Initial results and recommendations from this study were
presented at the Engineering Solutions to Indoor air Quality
Symposium held July 17-19, 2000, in Raleigh, North Carolina.
The conference was sponsored jointly by the Air & Waste
Management Association and the U.S. EPA. The research
was completed in the autumn of 2000, and final articles are
being prepared for submission to peer reviewed journals
(EPA Contact: Betsy Howard, 919-541-7915,
howard.betsvffliepa.gov)
Inside IAQ, Spring/Summer 2001
Page 4
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CANDLE BURNING AS A POTENTIAL SOURCE OF INDOOR AIR POLLUTION
Candle burning has been associated with human living
conditions for at least 1,000 years. Although no longer
primarily a means of lighting, candles are still popular in
households and certain public places, mainly for creating a
unique atmosphere. Candle sales in the United States keep
growing - about 10 to 15% per year in the last 10 years.
Industry estimates put 1999 sales at $1.3 billion for scented
candles and up to $2.3 billion for all candles.
A special issue that has drawn some attention recently is the
lead emissions from lead-wick candles. According to the
National Candle Association, most U.S. manufacturers have
ceased lead-wick production, but some imported candles on
the market still contain lead in their wicks. EPA bought 100
sets of candles that appeared to contain metal-cored wicks.
Eight sets had lead wicks with lead contents ranging from 51
to 74%. While burning, they emitted lead at a rate from 100
to 1400 Og/hour. Under certain indoor conditions, burning
these candles may result in lead concentrations above EPA
recommended thresholds. Furthermore, inhalation exposure
is not the only pathway for lead intake. Unlike gaseous air
pollutants, particle-bound lead tends to settle on interior
surfaces, where young children can be exposed to lead dust
through skin contact. The U.S. Consumer Product Safety
Commission is currently in the process banning the sales of
lead-wick candles in the United States.
Another issue associated with candle burning is the emissions
of fine particulate matter (PM). Although all candles
generate carbon particles during the burning process,
a well-designed and well-maintained candle emits negligible
fine PM because almost all the particles are consumed by
the flame. In fact, it is the combustion of the carbon
particles that gives the flame its bright golden color. This
process was artfully described by Michael Faraday in!861 in
his famous book The Chemical History of a Candle. On
the other hand, several factors (e.g., candle composition and
design, wick length, and drafty air) may result in imperfect
combustion. A smoldering candle could cause an indoor fine
PM concentration higher than permitted by the ambient air
quality standards. Heavy and frequent candle burning in
homes may be a contributing factor to soot deposition on
interior surfaces, causing blackened walls, ceilings, and
carpets. The exact mechanism of this phenomenon is not
well understood, however.
Protecting the public from these potential indoor pollution
problems requires a joint effort by the industry, the public,
and governments. Some manufacturers are developing low-
emission candles. Product labeling may help consumers
identify cleaner products and learn how to use them. To
some extent, burning candles is an art, and proper use of this
product can reduce emissions. Thus, public education is a
cost-effective way to deal with this kind of product. We
observed that blowing out candles could instantly produce a
large amount of particles. Some simple measures ~ using a
wet cloth, candle scissors, or snuffer - could greatly reduce
such emissions. Emissions from candles vary from product
to product and from time to time. To obtain representative
emissions data, there is a need to develop standard methods
for testing. (EPA Contact: Zhishi Guo, 919-541-0185,
guo. zhishi(g),epa. gov)
THE IMPACT OF OZONE ON INDOOR AIR QUALITY
EPA's Indoor Environment Mangement Branch (IEMB) is
conducting experiments to characterize the impact of ozone
on indoor air quality (IAQ). The goal of this research is to
improve our understanding of the relationship between ozone
and risk in indoor environments. Ozone is transported
indoors from ambient air and may be generated indoors by a
variety of sources including office equipment and consumer
appliances. Consumer appliances marketed as air cleaners
that intentionally produce ozone are of particular interest
because of their potential to create high ozone concentrations
and because they are advertised to improve IAQ by reacting
objectionable or odor causing volatile organic compounds
(VOCs) with ozone. The immediate focus of our work is to
characterize sources of ozone in indoor environments and
determine how ozone affects VOC and particle
concentrations in indoor air.
Little data are available that may be used to model and
predict the impact of ozone on IAQ. To fill this gap, we have
characterized ozone and oxides of nitrogen (NOJ emission
rates from selected consumer appliances under controlled
conditions in a room-sized environmental chamber and
evaluated their performance in our research test house.
These tests include limited evaluation of a feedback control
Inside IAQ, Spring/Summer 2001
Page 5
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system designed to maintain in-room ozone
concentrations at or below 50 parts per billion
(ppb).
We are currently investigating the impact of
operating an ozone generator air cleaner on VOC
concentrations in the controlled environment of the
test chamber. The objectives of these tests are to
identify reaction products and determine if
reactions proceed at rates that are consistent with
reaction rate constants that have been determined
for the troposphere. The reason for this objective
is obvious: ozone reacts too slowly with most
VOCs to have much impact on indoor air
concentrations - emission rates from the source(s)
and air exchange rates generally govern
concentrations. However, if an ozone generator
produces other radicals such as hydroxyls ("OH)
that react with VOCs much more quickly than
ozone, then operation of the device may actually
alter indoor air concentrations of some VOCs.
Whether or not this improves indoor air quality is
another matter. Some of our current research
findings are presented below.
Characterization of Ozone Generator Air
Cleaner Appliances
Emissions characterization tests were conducted
in the room sized environmental chamber (see
Figure 3) to determine how much ozone and NOx
these devices generate and what factors influence
generation rate.
Ozone emission rates for a widely marketed
appliance were determined at various dial set
points (in ft2 of floor treatment area) at 50% RH
in the room-sized environmental chamber and are
shown in Figure 4. We found that ozone
generation rates (<1 to >150 mg/h) were generally
consistent with the rates stated by the
manufacturers, although the relationship between
dial setting of the ozone generator and ozone
emission rate was not linear across the range of
the dial.
The chamber tests also revealed that ozone
generation rates decreased as relative humidity
increased for all appliances tested. As may be
seen in Figure 5, the rate of decrease was greatest
for the appliance with the highest ozone generation
rate.
Figure 3. Characterizing ozone emission rates in EPA's room-
sized test chamber.
Exhaust
n?nnp Monitor
C ^J.at Air Cleaner Inlet
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Chamber Inlet
onitor
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Figure 4. Ozone emission rates at generator set points
determined for an ozone generator air cleaner.
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0 200 400 600 800 1000 1200 1400 1600
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NOX [as nitrogen dioxide (N02)] is generated by silent discharge ozone
generators. As shown in Figure 6, NOX emission rates, determined at
50% RH, varied between appliances from different manufacturers and
ranged from 6 to 16 % mg/h of the ozone emission rate.
Performance of the Ozone Generator Appliance in the Research
Test House
A series of tests in the research test house investigated our ability to
predict indoor ozone concentrations from chamber derived emission
rates, and investigated the performance of a sensor-feedback control
system designed to maintain ozone concentrations at or below 50 ppb.
Inside IAQ, Spring/Summer 2001
Page 6
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We determined the ozone deposition velocity in the
house, determined the penetration factor for
ambient ozone, and used the IAQ model RISK to
predict the time history of ozone in the house
during operation of an ozone generator air cleaner.
We found that steady state predictions were
generally good (e.g., within ± 15% of observed)
though the model did not always represent the
concentration/time history as well. We also
observed that in-room ozone concentrations stayed
at or below 50 ppb when the generators were
operated with the controller activated (see Figure
7). The tests of the ozone generator air cleaner
with the sensor-controller activated were of 14 to
24 hr duration. Thus, these tests do not
characterize long-term performance or effects of
environmental variables on sensor-controller
performance.
We are in the process of evaluating data from
tests conducted to investigate the impact of the
ozone generator on concentrations of VOCs in the
environmental test chamber. Preliminary tests
with styrene and limonene, common indoor air
contaminants, suggest that the effect that the
ozone generator has on IAQ can be predicted
from ozone/VOC reaction rate constants published
by atmospheric researchers over the past 30
years. Reaction products for the styrene/ozone
tests are primarily benzaldehyde and
formaldehyde.
To summarize what we have learned to date:
Ozone generators may produce sufficient ozone to
create hazardous ozone concentrations in indoor
environments. The ozone emission rates vary as
a function of RH. NOX is produced as a
byproduct of ozone generation. The model RISK
appears to be useful for prediction of indoor
concentrations of ozone. Limited tests in the
research test house indicate that the feedback
control system provided by one manufacturer
maintains ozone concentrations at or below 50
ppb. On the other hand, though tests to date
indicate that operation of an ozone generator air
cleaner may result in somewhat lower
concentrations of some compounds, greater
exposure to formaldehyde and other aldehydes
and organic acids is likely to result. (EPA
Contact: Mark A. Mason, 919-541-4835.
mason.mark @epa.gov)
Figure 5. The relationship between ozone generation rate and
RH for three ozone generator air cleaners.
11
y=-07563x+114.23
y=-02317x + 45.415
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Charter RH(!4|
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!M2,McdelB
Figure 6. NOx emission rates for selected ozone generator air
cleaners determined at 50% RH.
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Ozone Emission Rate (mg/h)
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x M2, Model B - - Regression All M1 ^^— Regression All M2
Figure 7. Ozone concentration out of doors and in a room of the
research test house with ozone sensor-controller system of the
ozone generator air cleaner activated.
I Ozone in Den
Ozone Outdoors
Inside IAQ, Spring/Summer 2001
Page 7
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EPA's Indoor Environment Management Branch is cosponsoring
Indoor Air 2002
the largest international conference dedicated to
scientific and professional research in the indoor air sciences.
The conference will be held in Monterey, California, June 30 to July 5, 2002.
Plan now to attend this important event.
Abstracts must be submitted by October 1, 2001. Further information
is available from the web site at www.indoorair2002.org.
United States
Environmental Protection Agency FIRST CLASS MAIL
National Risk Management Research Laboratory POSTAGE AND FEES PAID
PPA
Indoor Environment Management Branch
MD-54 PERMIT No. G-35
Research Triangle Park, NC 27711
Official Business
Penalty for Private Use
$300
EPA/600/N-01/002, Spring/Summer 2001
An Equal Opportunity Employer
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