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Engineering Solutions to

Indoor Air Quality Problems

Symposium

July 17-19, 2000

Raleigh, NC

(See Page 11 for Call for Papers)

 United States Environmental Office of Research and Development

Protection Agency Research Triangle Park, NC 27711

EPA/600/N-99/002 Spring/Summer 1999 

 EPA Inside IAQ

EPA's Indoor Air Quality Research Update

In This Issue Page

Fungal Spores and the Influence of Humidity,

 Velocity, and Amplification on Emission Rates ...... 1

Evaluation of Potential P2 Approach

 for Reducing Photocopier VOC Emissions ......... 4

Testing of IAQ Simulation Software ............... 5

Evaporative Emissions in Ventilated Rooms .......... 6

Summaries of Recent Publications ................. 8

Glossary ................................... 10

Call for Papers .............................. 11

FUNGAL SPORES AND THE INFLUENCE OF

HUMIDITY, VELOCITY, AND AMPLIFICATION ON

EMISSION RATES

Although a significant amount of work has been done to

elucidate the conditions under which fungi will grow on

material surfaces, little information is available that

quantitatively relates surface concentrations to airborne

concentration and ultimately exposure. This article discusses

the impact of relative humidity (RH), air velocity, and surface

growth on the emission rates of fungal spores from the surface

of contaminated material.

The two factors that were anticipated to have the most impact

on emissions were air velocity and RH. RH controls the

release of spores by some fungi. High RH is important for

those active release mechanisms that depend on the rupture of

turgid cells, while tissue desiccation in low RH is important to

another class of release mechanisms. The velocity of air

flowing over fungal colonies is known to be important to

dissemination both as a source of energy for liberation and to

enhance mass transport for humidity-driven processes.

In previous experiments, we found that fungal emissions were

influenced by complex interactions among RH, surface

growth, and material characteristics. RH has a tremendous

impact on the dissemination of both Penicillium and

Aspergillus spores. Under the high RH conditions where

growth occurred, there was little or no release of spores.

However, as the RH was lowered, spore release was

triggered. While the data are limited to these few cases, the

potential impact of the results on current control and

remediation practices was profound. Lowering uncontrolled

RH is almost always a recommended practice. The data in

this study point out that during remediation this could be the

wrong strategy and could lead to increased short-term

emissions.

(Continued on Page 2)
Inside IAQ, Spring/Summer 1999 Page 2

The objectives of this study were to: 1) initiate experiments

relating surface load or concentration (for new growth) to the

emission of fungal spores, and 2) measure the impact of air

velocity at a variety of RHs. The experiments were conducted

in the Dynamic Microbial Test Chamber (DMTC). The

DMTC is a room-sized test facility designed to conduct

studies on the conditions and factors that influence

biocontaminant emissions and dissemination. It is a cube with

inside dimensions of 2.44 m, stainless steel walls and floor,

and an acrylic drop-in ceiling. Temperature (18-32EC) and

RH control (55 to 95%) are provided through an air handler

unit (AHU) with an air circulation rate between 1.4 and 4.8

m

3

/min.

The chamber was adapted to contain eight miniducts as shown

in Figure 1. The blower forces the conditioned DMTC air into

a High Efficiency Particulate Air (HEPA) filter, from which

the air for the eight miniducts is obtained. The channel design

was chosen for the miniducts to limit the total amount of air

required for a single test, allowing multiple tests to be run

simultaneously, and simulate flow conditions in a heating,

ventilating, and air-conditioning duct.

Three newly purchased common duct materials were studied:

two fiberglass duct liners (FDL-A and FDL-B) and one

fiberglass ductboard (FGD). In appearance, these duct liners

were very similar, with an uncoated surface intended to be

attached to a rigid duct material and a polymer coated surface

intended to be in contact with the moving air in the duct. FDLB contained a permanent (bound) antimicrobial in the coating

of the airstream surface. Penicillium chrysogenum and

Aspergillus were selected as the test organisms. P.

chrysogenum has been reported as one of the most frequently

isolated molds from the air, housedust, and surfaces of indoor

environments, and has been isolated from a number of airInside 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

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Inside IAQ

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Research Triangle Park, NC 27711

Fax: 919-541-2157

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Also, check our home page on the Internet at:

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Figure 1. Dynamic Microbial Test Chamber.

conditioning systems in environments where patients were

suffering from allergic disease. The materials were artificially

soiled and then inoculated in an aerosol deposition chamber.

The targeted amount of dust for deposition was

approximately 100 mg dust/100 cm2. This level has been

considered moderately soiled in previous experiments and

was selected to relate these data to previous experiments.

After artificial soiling and inoculation, the 30.5 x 91.4 cm (1

x 3 ft) pieces of test material were placed in the miniducts.

Temperature and RH throughout the miniducts were

maintained at 23.5EC and 94%, respectively. The air velocity

through the miniducts was 2.5 m/s (500 ft/min). At the start

of an emission rate determination, the chamber RH was

lowered from 94% to the test RH (i.e., 64%) by lowering the

RH setting on the AHU. Six isokinetic, 1-hour air samples

were collected using the Mattson-Garvin slit-to-agar sampler

for culturable bioaerosols. At the completion of each sixth

hour sample, chamber RH was returned to the maintenance

RH of 94%. No experiments were performed within 2 days

of any other to allow the surface of the materials to recover

from the decreased RH and to make certain the starting point

for all emission measurements was the same. Surface samples

were collected at weekly intervals, at least 1 day after the

bioaerosol sample was collected.

Colony forming units (CFUs) were counted shortly after visible

growth was first noted and again as moderate growth became

apparent. To calculate the emission rates, the CFUs on the

Mattson-Garvin plates were identified and enumerated, and the
Inside IAQ, Spring/Summer 1999 Page 3

1000

CFUs/min were determined. The value was adjusted for the total

flow rate and divided by the area of the emitting surface.

Figure 2 shows the impact of surface load during log-phase

growth on the emission rates of fungal spores from the surface

of the duct material using A. versicolor as the test organism.

The test material, FDL-B, was inoculated with two different

concentrations of A. versicolor. Emissions were measured at

64% RH. The columns represent surface growth and are

referenced to the left axis as Log10 CFU/10 cm2. The two

levels of inoculum used are denoted as lower and higher. The

lower inoculum was approximately 102 CFU/10 cm2, and the

higher inoculum was approximately 103 CFU/10 cm2. Error

bars are included for weeks 0 and 1 to show that no significant

difference was measured between the levels of surface growth

after the initial inoculation. The lines represent the spore

emissions results and are plotted on a log scale against the

right axis as CFU/m2/min. None of the differences between the

emission rates were significant except at week 3 (see error

bars). When comparing the surface and the emission data, it

is apparent that, for A. versicolor under these conditions,

surface load directly influences the emission rate. In other

words, as the surface concentration of organisms increased

during log-phase growth, the emission rate increased until a

stable population was reached, and then the emissions

appeared to remain essentially constant.

Figure 2. Surface growth vs. spore emissions for A.

versicolor at lower and higher inoculum levels.

Tables 1 and 2 present the first hour emission rate for P.

chrysogenum and A. versicolor, respectively. The surface

concentration was monitored to document that a stable

population of organisms had been established on the surfaces

of all the materials for at least 12 weeks.

Table 1. Emission (CFU/m2/min) of P. chrysogenum spores

at four different airflow rates and RHs.

MATERIA

L

RH

%

AIRFLOW, m/sec.

0.5 1.0 1.5 2.5

FDL-B 64 9 13 409 804; 2023; 1249

70 5; 1 28 228 972; 1480

84 1 1 59 150

94 2 5 124;127 81

FDL-A 64 610 155 465 813; 2392; 1501

70 27;7 30 229 710; 1385

84 0 25 234 287

94 26 7 145; 75 69

FGD 64 13 20 88 333; 854; 267

70 8; 1 6 17 335; 162

84 1 0 50 12

94 17 0 0 47

Table 2. Emission (CFU/m2/min) of A. versicolor spores at

four different airflow rates and RHs.

MATERIAL RH

%

AIRFLOW, m/sec.

0.5 1.0 1.5 2.5

FDL-B 64 1 11 45 170; 100; 190

70 0; 1 1 25 60; 20

84 0 1 0 0

94 2 0 0; 0 11

FDL-A 64 24 44 52 43; 15

70 11;

2

26 17 8; 14

84 1 0 10 3

94 0 0 0; 7 20

FGD 64 0 4 138 567; 151; 543

70 0; 0 5 66 242; 182

84 1 0 0 22

94 2 0 0; 0 0

The first column lists the three different materials tested, and

the second column lists the four RHs at which the emissions

were measured. The final four columns show the emission

rates for the two test organisms at the four airflows used in

the study. In a number of cases (e.g., FDL-B, 64% RH at 2.5

m/s), multiple values, separated by a semi-colon, are

reported. These values are replicate measurements from

different experiments. In general, these data are in good

agreement.

As shown previously, the emission rates were inversely related

to the RH at airflows of 2.45 m/s. In other words, as the RH

decreased, the emission rate increased. The current experiment

generally confirms that relationship at the lower airflow rates.
Inside IAQ, Spring/Summer 1999 Page 4

 However, once the emission rate becomes too low, the natural

variability overwhelms our ability to measure a difference.

When the data from the different airflows are compared, the

emission rate is related to the flow rate across the

contaminated surface. As the flow rate increases, so do the

emission rates. This was seen at all four humidities included

in the study. Overall, the emission rates were notably lower

for the A. versicolor than the P. chrysogenum regardless of

RH or airflow.

While additional research will be required to relate these data

to exposure, the emission rates measured in these experiments

support data from our previous study, and modeling the

results shows that the emission rates produced room

concentrations consistent with field observations reported

from the literature.

In summary, the results show a complex interaction of factors.

For a limited data set, emission rates are inversely proportional

to RH, but directly related to airflow and surface loading. This

work was performed by Research Triangle Institute under

cooperative agreement number 000000. (EPA Contact: Marc

Menetrez, 919-541-7981, menetrez.marc @epa.gov)

EVALUATION OF POTENTIAL P2 APPROACH

FOR REDUCING PHOTOCOPIER VOC EMISSIONS

This project is studying the potential for reducing the

emissions of volatile organic compounds (VOCs) from office

photocopy machines, through modifications to the raw

materials or the manufacturing process used in producing the

toners used in these machines.

In an earlier EPA report (EPA-600/R-98-080), concentrations

of selected VOCs were reported in the head space (static)

above samples from three lots of nominally identical toners,

raised to temperatures as high as 150 oC (the lower end of the

range at which the copier fusing mechanism typically

operates). According to the manufacturer, these three toner

lots nominally had the same chemical composition, and were

manufactured for use in the same copy machine. Yet the

samples from one of the lots consistently provided head-space

concentrations 50 to 80% lower than those from the other two

lots, for each of four specific hazardous organic compounds

that were measured. The four VOCs – styrene, ethylbenzene,

o-xylene, and m,p-xylene – are likely impurities resulting from

the polymer used in manufacturing the toners.

In the earlier report, it was noted that the toner lot producing

the lower head-space concentrations had been manufactured

using a continuous extrusion process, whereas the other two

had been manufactured at different facilities using a batch

process involving Banbury mixers. No information was

available regarding the purity of the specific polymer

feedstocks used in these manufacturing processes at different

sites.

A follow-on study is now underway to better define the extent

to which modifications to the toner manufacturing process

might offer pollution prevention (P2) opportunities for

reducing VOC emissions from photocopiers. This follow-on

effort initially involves head-space testing on toner samples,

as did the earlier effort discussed above, but addresses a

larger number of samples in an effort to systematically

separate out the effects of the different variables that could be

impacting the observed results. These variables include:

1) Manufacturing process. Three processes appear to be

commonly employed: continuous extrusion under vacuum;

continuous extrusion at atmospheric pressure; and batch

mixing (e.g., using a Banbury mixer).

2) Purity of the feedstock polymer.

3) Time at which the toner sample was collected during the

manufacturing run. At issue is the inherent variability in

toner characteristics over the course of a given run, with

a fixed process and feedstock.

4) Manufacturer and/or the machine for which the toner is

being produced (which would impact the nature of the

polymer and chemical composition of the toner). If the

manufacturing process or the feedstock purity is having a

major impact on VOC emissions, is this impact consistent

between vendors and toner types?

This study will address specific VOCs, in addition to the four

listed above, if other compounds are also found at high levels

in the head space.

If the results from this head space testing define an important

and consistent impact of one or more variables on head space

VOC levels, the study may be extended to include small

chamber testing of VOC emissions from copied paper

produced by a machine using both the lower- and the higheremitting toners. The objective would be to assess the extent

to which the lower-emitting toners would reduce VOC

emissions into the office space from copied paper after it has

left the photocopier room. (EPA Contact: Bruce Henschel,

919/541-4112, henschel.bruce@epa.gov)
Inside IAQ, Spring/Summer 1999 Page 5

TESTING OF IAQ SIMULATION SOFTWARE

An IAQ simulation software package, tentatively named the

Simulation Tool Kit for Indoor Air Quality and Exposure or

STKi, has recently started its beta test. STKi is a collection of

Microsoft Windows-based IAQ simulation programs with

similar user interfaces. It consists of a general-purpose

simulation program and a series of stand-alone, specialpurpose simulation programs. 

The general purpose simulation program is designed to give the

user the flexibility to simulate a wide range of indoor air

pollution scenarios. It is capable of making multi-zone and multipollutant simulations and allows gas-phase chemical reactions.

The special purpose simulation programs deal with mass

transfer models. In recent years, modeling of indoor sources

has gradually shifted from simple, statistical models to more

complex, fundamentally based models. While the latter

provide improved accuracy and validity, their usefulness has

been hindered by their increased complexity. Potential users

may want to avoid unfamiliar equations and the tedious

calculations behind them. The special-purpose simulation

programs in STKi help resolve this problem by shielding the

users from mathematical details and allowing them to

concentrate on IAQ-related issues.

An array of good IAQ simulation programs have been

developed and some can be easily obtained. STKi is not

designed to replace them. Instead, it complements and

supplements them. STKi is targeted mainly for advanced

users, those who are directly involved in IAQ exposure

estimation, risk assessment, or IAQ research. STKi is not an

expert system. It is the user’s responsibility to determine what

model parameters to choose. Several emissions databases are

being developed in Europe and North America. Those

databases plus other sources can be useful tools in parameter

selection. STKi does not predict the air movement inside a

building, either. However, it does allow the user to input the

airflow data from existing air infiltration or computational

fluid dynamic models. The first public release of STKi is

expected in the winter of 1999 and will include the five

programs shown in Table 3.

Table 3. Programs included.

Carpet.EXE a model for VOC emissions from new

carpet

GPS.EXE general-purpose simulation program

PM.EXE a model for indoor particulate matter

Spill.EXE models for indoor solvent spill

VBX.EXE models for predicting VOC emissions from

solvent-based indoor coating materials based

on product formulation

The whole package will be developed in a cumulative

manner. More special-purpose programs will follow. Some

candidate programs currently under consideration are listed

in Table 4.

Table 4. Programs proposed.

Chem. EXE model shell for indoor air chemistry 

Latex.EXE latex paint emission models

Pest.EXE fugacity models for indoor application

of pesticides

Water.EXE models for VOC emissions from water

use (e.g., shower, washing machine,

and dish washer)

WBC.EXE models for water-based cleaners (liquid

pool and wet film)

We welcome input from potential users, especially about their

needs and the programs they would like included. (EPA

Contact: Zhishi Guo, 919-541-0185, guo.zhishi@epa.gov)
Inside IAQ, Spring/Summer 1999 Page 6

0

25

50

75

100

125

150

0.00 0.10 0.20 0.30 0.40

Velocity (m/s)

Distance from surface (mm)

Center

East

West

North

South

EVAPORATIVE EMISSIONS IN VENTILATED

ROOMS

VOCs are emitted from building materials, especially in many

new buildings. Emissions occur in a chainlike process:

diffusion inside the emitting material; crossing the surface-air

interface; transport across the mass transfer boundary layer;

and mixing into the bulk air. In any particular material, one of

these processes may be rate controlling. For freshly applied

liquid films, emissions are generally controlled by evaporation

from the surface and depend on local airflow parameters such

as temperature and velocity.

Experiments at different air velocity levels were performed in

a full-scale ventilated chamber to investigate the influence of

local airflow on evaporative emissions from a surface. The

experiments included velocity measurements of the flow over

the surface and measurements of chamber air concentrations.

The research was conducted in IEMB's large chamber by

Claus Topp of Aalborg University and was supported by the

Danish Technical Research Council.

Experiments were performed at EPA in a full-scale ventilated

chamber (4.0 x 2.8 x 2.6 m; 29 m3). Four slots provide

supply air to the chamber, one at the foot of each wall. Three

of the inlet slots direct the flow upward along the wall, and the

fourth inlet slot directs the flow along the floor. The return is

located at the center of the ceiling.

The experiments were performed at two different velocities

with temperature and RH kept fixed. In all experiments, the

air exchange rate was 1 air change per hour (ACH), and the

amount of recirculating air was changed to obtain different

velocity levels in the chamber. Two experiments were

performed at a total supply flow rate of 5 ACH (recirculation

rate of 4 h-1), and two experiments were performed at a total

supply flow rate 2 ACH (recirculation rate of 1 h-1).

In each of the experiments, a 1.48 m2 wood board was placed

at the center of the chamber floor. After conditioning, pure

decane (C10H22, equilibrium vapor pressure Cv = 12115 mg/m3

and molecular diffusion coefficient D = 0.0207 m2/h) was

applied to the top surface of the board. Smoke tests showed

that the flow over the wood board was parallel to the surface.

Velocity profiles were measured to obtain detailed knowledge

of the boundary layer flow over the wood board. The profiles

were measured with a hot-wire anemometer at the center of the

wood board and at 250 mm east, west, north, and south of the

center, respectively. The airflow in the chamber was from

east to west.

The concentration of decane in the chamber air was

determined by gas chromatography. Chamber air was pulled

through sorbent traps at a known flow rate using mass flow

controllers and a vacuum pump. Analytes were extracted

from the traps with carbon disulfide (CS2), and the concentration of decane in the extract was determined by

injecting a subsample of the extract onto the column of a gas

chromatograph equipped with a mass selective detector.

The velocity profiles over the wood board are shown in

Figures 3 and 4, for 2 and 5 ACH, respectively. As expected,

the maximum velocity decreases with distance from the inlet.

The velocities at the north and south locations, though, are

somewhat different indicating that the flow is not symmetric

around the board. The difference increases with the flow rate.

For 2 ACH, the maximum velocities occur approximately 3

cm above the surface and, for 5 ACH, they occur 2 cm above

the surface. As the flow rate is decreased, the maximum

velocities drop accordingly as shown in Table 5. 

Table 5. Maximum velocities over the wood board.

ACH Center

(m/s)

East

(m/s)

West

(m/s)

North

(m/s)

South

(m/s)

2 0.27 0.32 0.22 0.23 0.17

5 0.78 0.86 0.64 0.91 0.29

Figure 3. Velocity profiles over the

 wood board for 2 ACH.
Inside IAQ, Spring/Summer 1999 Page 7

0

25

50

75

100

125

150

0.00 0.20 0.40 0.60 0.80 1.00

Velocity (m/s)

Distance from surface (mm)

Center

East

West

North

South

Figure 4. Velocity profiles over the

wood board for 5 ACH.

Measurements of chamber concentrations over time show that

chamber concentration reaches its maximum after approximately 0.5 h for 2 ACH and after 1 h for 5 ACH. Then the

concentration drops rapidly within 10 h. In the early stage of

the emission process, there is a significant difference between

concentrations from one velocity level to another but after

approximately 2 h the concentration levels are very similar. In

general, there is good agreement between the experimental

data and the model predictions using the mass transfer model

developed by IEMB, but the model seems to predict lower

peak concentrations. Concentrations from experiments with

the same total supply flow rate are very similar although there

is a 10 % difference between the peak concentrations for 2

ACH. For 5 ACH, there is a difference of 12 % in the amount

of VOC applied but the difference in concentration is not as

significant. 

The emission rate can be conveniently expressed in terms of

a mass transfer coefficient as shown in Table 6.The standard

deviations from the regressions are within 12 %, which is

satisfactory. The mass transfer coefficients from experiments

with identical flow rates agree within 10 %.

Table 6. Mass transfer coefficients from non-linear

 regression.

Experiment ke

(m/h)

Std.Dev.

(m/h)

Std. Dev

(%)

1 10.29 0.84 8.2

2 11.07 1.29 11.7

3 4.01 0.19 4.7

4 3.64 0.21 5.8

Results also show that emissions, expressed in terms of the

mass transfer coefficient, increase with velocity for fixed

temperature, RH, and air exchange rate. This emphasizes the

importance of testing materials at the correct velocity and

turbulence level in order to obtain the actual emission rate for

a given product. 

As noted, the results agree with the IEMB model predictions

and show that, after reaching its maximum, the chamber

concentration drops rapidly within 10 h, which is consistent

with previous results obtained by IEMB. IEMB studied the

emission characteristics of a mixture of organic compounds,

including decane, and concluded that the first phase of the

emission process is controlled mainly by evaporation from the

surface. After that, the decay rate slows as diffusion

transport inside the material becomes the controlling

mechanism of the emission process.

In summary, two experiments were performed at each

velocity level, and the results are consistent, indicating a high

level of repeatability. It was found that the velocity level in

the boundary layer flow over the surface has a strong impact

on the mass transfer coefficient as the mass transfer

coefficient increases in proportion to the velocity. This

emphasizes the importance of testing materials at the correct

velocity and turbulence level to overcome scaling problems

when transferring results from a small-scale test chamber to

a full-scale ventilated room. (EPA Contact: Les Sparks, 919-

541-2458, sparks.les@epa.gov)
Inside IAQ, Spring/Summer 1999 Page 8

SUMMARIES OF RECENT PUBLICATIONS

Controlling Souces of Indoor Air

Pollution Through Pollution Prevention - This paper overviews recent

research on the application of P2

techniques for improved IAQ: 1)

developing methods and tools that can

be used to evaluate emissions from

equipment or products; 2) developing

generic P2 solutions; 3) identifying

high-emitting raw materials or components of products; and 4) evaluating lowemitting materials. Test method guidelines for measuring emissions from

office equipment were developed and

then evaluated by testing four dryprocess copiers in one chamber and by

conducting a four-laboratory evaluation

using one of the copiers. For aerosol

consumer products, measurement

methods and models were developed

that can be used to better understand

aerosol behavior so that more

efficacious and less toxic products can

be developed. A generic, innovative

spray nozzle for use with precharged

aerosol containers was developed and

evaluated. The new design allows for

the reformulation of selected aerosol

consumer products using water and air

in place of VOC solvents and hydrocarbon propellants, respectively. Highemitting components of common types

of finished engineered wood products

were identified by evaluating emissions

at each stage of the manufacturing

process. Three fiber panels and three

coatings were then identified as

potential low-emitting alternative

materials. Four types of printed circuit

board laminates were evaluated.

Glass/epoxy laminates and glass/lignincontaining epoxy resin laminates

emitted fewer volatile compounds than

the two paper/phenolic resin-based

laminates. Source: Proceedings of the

ASHRAE Conference, “IAQ & Energy

‘98. Using ASHRAE Standards 62 and

90.1 to Provide Acceptable Indoor Air

Quality and Energy Efficiency” (EPA

Contact: Kelly W. Leovic, 919-541-

7717, leovic.kelly@epa.gov)

Emissions of Odorous Aldehydes

from Alkyd Paint - Odorous aldehyde

emissions from a commonly used alkyd

paint were measured and characterized.

Initial formulation analysis indicated no

measurable aldehydes in the liquid

paint. However, small environmental

chamber tests showed that, for each

gram of the alkyd paint applied, more

than 2 mg of aldehydes (mainly

hexanal) were emitted during the curing

(drying) period. The emission profiles

of aldehydes were very different from

those of other VOCs such as alkanes

and aromatics. Since no measurable

aldehydes were found in the original

paint, it is suspected that the aldehydes

emitted were produced by autoxidation

of the unsaturated fatty acid esters in

the alkyd resins. It was found that the

hexanal emission rate can be simulated

by a mathematical model assuming that

the autoxidation process was controlled

by a consecutive first-order reaction

mechanism. The mathematical model

was used to predict the indoor air

hexanal concentrations for a typical

application of the alkyd paint tested.

The result indicated that the aldehyde

emissions can result in prolonged

(several days) exposure risk to

occupants. The occupant exposure to

hexanal emitted from alkyd paint also

could cause sensory irritation and other

health concerns. Atmospheric

Environment, 32, 20, 3581-3586, 1998.

(EPA Contact: John Chang, 919-541-

3747, chang.john@epa.gov) 

Estimation of the Rate of VOC

Emissions From Solvent-Based

Indoor Coating Materials Based on

Product Formulation - Two computational methods are proposed for

estimation of the emission rate of VOCs

from solvent-based indoor coating

materials based on the knowledge of

product formulation. The first method

utilizes two previously developed mass

transfer models with two key

parameters -- the total vapor pressure

and the average molecular weight for

total volatile organic compounds

(TVOCs) -- being estimated based on

the VOC contents in the product. The

second method is based on a simple,

first-order decay model with its

parameters being estimated from the

properties of both the source and the

environment. All the model parameters

can be readily obtained. Detailed

procedures for computing the key

parameters are described by using

examples. The predictive errors were

evaluated with small chamber data, and

the results were satisfactory. Thus, the

proposed methods provide a way to

predict the VOC emissions in the indoor

environment without having to conduct

costly chamber testing. The two

proposed methods work for both

TVOCs and individual VOCs. Pros

and cons for each method are discussed.

Source: Atmospheric Environment,

Vol. 33, No. 8, pp. 1205-1215, 1999.

(EPA Contact: Zhishi Guo, 919-541-

0185, guo.zhishi@epa.gov)
Inside IAQ, Spring/Summer 1999 Page 9

Exposure and Emission Evaluations

of Methyl Ethyl Ketoxime (MEKO) in

Alkyd Paints - Small environmental

chamber tests were conducted to

characterize the emissions of a toxic

chemical compound -- methyl ethyl

ketoxime (MEKO) -- from three

different alkyd paints. It was found that

MEKO emissions occurred almost

immediately after each alkyd paint was

applied to a pine board. Due to the fast

emission pattern, more than 90% of the

MEKO emitted was released within 10

hours after painting. The peak concentrations of MEKO in chamber air

correlated well with the MEKO content

in the paint. Material balance showed

that good recovery (more than 68%)

was achieved between the MEKO

applied with the paint and the MEKO

emitted. The chamber data were

simulated by a first order decay

emission model assuming that the

MEKO emissions were mostly gasphase mass transfer controlled. The

model was used to predict indoor

MEKO concentrations during and after

painting in a test house. It was found

that the predicted test house MEKO

concentrations during and after the

painting exceeded a suggested indoor

exposure limit of 0.1 mg/m

3

for all three

paints. The predicted MEKO

concentrations exceeded even the lower

limit of a suggested sensory irritation

range of 4 to 18 mg/m

3

 with two of the

three paints tested. The model was also

used to evaluate and demonstrate the

effectiveness of risk reduction options

including selection of lower MEKO

paints and higher ventilation during

painting. Source Indoor Air,8, 295-

300, 1998. (EPA Contact: John Chang,

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

Indoor Emissions from Conversion

Varnishes - Conversion varnishes are

two-component, acid-catalyzed

varnishes that are commonly used to

finish cabinets. They are valued for

their water- and stain-resistance, as

well as their appearance. They have

been found, however, to contribute to

indoor emissions of organic

compounds. For this project, three

commercially available conversion

varnish systems were selected. An EPA

Method 24 analysis was performed to

determine total volatile content, and a

sodium sulfite titration method was

used to determine uncombined (free)

formaldehyde content of the varnish

components. The resin component was

also analyzed by gas chromatography/mass spectroscopy (GC/MS)

(EPA Method 311 with an MS

detector) to identify individual organic

compounds. Dynamic small chamber

tests were then performed to identify

and quantify emissions following

application to coupons of typical

kitchen cabinet wood substrates, during

both curing and ageing. Because

conversion varnishes cure by chemical

reaction, the compounds emitted during

curing and ageing are not necessarily

the same as those in the formulation.

Results of small chamber tests showed

that the amount of formaldehyde

emitted from these coatings was 2.3 to

8.1 times the amount of free

formaldehyde applied in the coatings. A

long-term test showed a formaldehyde

emission rate of 0.17 mg/m

2

/h after

115 days. Source: Journal of the Air &

Waste Manage. Assoc. 48: 924-930,

1998. (EPA Contact: Elizabeth M.

Howard, 919-541-7915, howard.betsy

@epa.gov)
Inside IAQ, Spring/Summer 1999 Page 10

ERRATA

Please note the following typographical errors in the

Spring/Smmer ‘98 issue of Inside IAQ. Table 4, Page 7, the

first column, the entry “Formaldehyde” should be

“Formaldehyde*” and the entry “Formaldehyde*” should be

“Heptachlor.”

GLOSSARY

ACH - Air Change per Hour

AHU - Air Handling Unit

CFU - Colony Forming Units

DMTC - Dynamic Microbial Test

Chamber

FDL - Fiberglass Duct Liner

FGD - Fiberglass Ductboard

GC/MS - Gas Chromatography/Mass Spectography

HEPA - High Efficiency Particulate Air

IAQ - Indoor Air Quality

IEMB - Indoor Environment Management Branch

MEKO - Methyl Ethyl Ketoxime

NRMRL - National Risk Management

Research Laboratory

P2 - Pollution Prevention

RH - Relatiive Humidity

STKi - Simulation Tool Kit for IAQ

and Exposure

TVOC - Total Volatile Organic

Compound

VOC - Volatile Organic Compound
Inside IAQ, Spring/Summer 1999 Page 11

Call for Papers

Engineering Solutions to Indoor Air Quality Problems

Engineering Solutions to Indoor Air Quality Problems, an international symposium cosponsored

by the Air and Waste Management Association and EPA’s National Risk Management Research

Laboratory, will be held July 17-19, 2000, in Raleigh, NC, at the Sheraton Capital Center.

Papers are invited on the following topics:

! Managing the Risk of Indoor Air Pollution

! Indoor Air Source Characterization

Methods

! Indoor Air Source Management

! Low Emitting/Low Impact Materials

Development (Pollution Prevention)

! Biocontaminant Prevention and Control

! Indoor Air Cleaning Methods

! Asthma and Children’s Health in the

Indoor Environment

! Ventilation

! HVAC Systems as Sources of Indoor

Air Pollution

! Air Duct Cleaning

! Particles and Particle Entry into the

Indoor Environment

! Indoor Air Quality Modeling

! Costs of Managing Indoor Air Quality

! Evaluation and Verification of IAQ

Alternatives

The symposium will consist of one general session so that participants will be able to attend all

sessions. A poster session, continuing education courses, and an exhibition of related products

and services are also planned.

Send abstracts of 200-300 words by January 10, 2000, to: Michael C. Osborne, U.S. EPA, MD54, Research Triangle Park, NC 27711; Telephone (919)-541-4113; Fax (919)-541-2157; E-mail:

osborne.michael@epa.gov. Abstracts should include paper title and author(s) names, address(es),

and phone, fax number(s), and e-mail address.
Attention Foreign Subscribers

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foreign addresses were lost. If you are a

foreign subscriber (or know of one), please

resubmit your address/fax/ e-mail as

noted on Page 2. We apologize for any

inconvenience.

United States

Environmental Protection Agency

National Risk Management Research Laboratory

Indoor Environment Management Branch

MD-54

Research Triangle Park, NC 27711

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