United States Office of Research am
^Environmental Protection Development
ncy (RD-672)
EPA/400/1-89/001D
<&EF¥V Report to Congress on
Indoor Air Quality
Volume
Indoc Air Pollution
Research Needs Statement
Issued under Section 403(e), Title IV of the Superfund
Amendments and Reauthorization Act of 1986 (SARA)
-------
Report to Congress
on
Indoor Air Quality
Volume III: Indoor Air Pollution
Research Needs Statement
Issued Under
Section 403(e), Title IV
of the
Superfund Amendments and Reauthorization
Act (SARA) of 1986
Prepared By:
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
-------
CONTENTS
I. Overview of Indoor Air Pollution Research Needs 1
A. Purpose of the Indoor Air Research Program 1
B. The Indoor Air Research Setting 2
C. Radon 4
D. Summary of Research Needs 5
II. Research Needs 11
A. Risk Assessment 11
1. Framework for Assessing Risk 12
2. Special Topics for Assessing Risk 14
3. Supporting Information for Risk Assessment 14
B. Exposure Assessment and Modeli ng Needs 15
1. Monitoring and Measurement 16
2. Modeling 17
3. Data Management and Quality Assurance 17
C. Source-Specific Needs 18
1. Combustion Sources 18
2. Material Sources 23
3. Activity Sources 28
4. Ambient Sources 31
5. Sources of Biological Contaminants 33
D. Control Techniques 35
1. Source-Specific Controls 35
2. Ventilation Strategies 36
3. Air Cleaners 36
E. Building System Needs 38
F. Crosscutting Research 40
G. Technology Transfer 41
III. Additional Reading 43
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TABLES
Page
Summary of major indoor air research needs 6
FIGURES
Indoor air quality hazards 11
Seven-step risk characterization methodology 13
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NOTE
EPA's Science Advisory Board reviewed this research needs statement on
March 29, 1989. The Agency is grateful for the thoughtful comments and
suggestions of the SAB. At the time the SAB final report is received by EPA,
the Research Needs Statement will be modified and a more detailed research
plan will be prepared.
m
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I. OVERVIEW OF INDOOR AIR POLLUTION RESEARCH NEEDS
A. PURPOSE OF THE INDOOR AIR RESEARCH PROGRAM
In October 1986, Congress passed the Superfund Amendments and Reauthoriza-
tion Act (SARA, PL 99-499) which included the Radon Gas and Indoor Air Quality
Research Act (Title IV). This act provided for the first time a direct
Congressional mandate for a national indoor air research program. While no
regulatory program is authorized under this legislation, EPA is directed to
undertake a comprehensive research and development effort, including the
coordinati'on of government and private efforts, with the ultimate goal of
disseminating information to the public regarding indoor air control techniques
and mitigation measures.
Title IV of the Superfund legislation directs the Environmental Protection
Agency and other federal agencies to establish an indoor air quality research
program designed to promote the understanding of health problems associated
with indoor air pollutants. SARA directs that EPA coordinate with federal,
state, local, and private sector research and development efforts related to
improvement of indoor air quality and assess appropriate federal actions to
mitigate environmental and health risks associated with indoor air quality
problems. The statute encourages federal agencies to disseminate information
regarding indoor air pollutant sources and concentrations, high risk building
types, measurement instruments, and health effects, as well as to recommend
methods for the prevention and abatement of indoor air pollution.
Research program requirements under Section 403 include identification,
characterization, and monitoring (measurement) of the sources and levels of
indoor air pollution; development of instruments for indoor air quality data
collection; and the study of high risk building types. The statute also
requires research directed at identifying effects of indoor air pollution on
human health. In the area of mitigation and control the following are required:
development of mitigation measures to prevent or abate indoor air pollution;
demonstration of methods for reducing or eliminating indoor air pollution;
development of methods for assessing the potential for radon contamination of
new construction, and examination of design measures to avoid indoor air
pollution.
August 1989
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B. THE INDOOR AIR RESEARCH SETTING
The ultimate goal of SARA Title IV is the dissemination of information
to the public. Therefore, the central purpose of EPA's Indoor Air Research
Program is to provide information useful for identifying and characterizing
overall health risks in the indoor environment and for reducing exposures that
pose an adverse health risk. The objectives of this research are to both
determine the causes of excess risks and to identify those activities and
technologies that have the greatest potential for reducing risks in the indoor
environment.
Research devoted to indoor pollutants and their sources is responsive to
the goal of indoor air quality guidance rather than regulation. A regulatory
program requires a multitude of scientifically based outputs that are judged
by scientists and interpreted by those who establish the regulations. The
public and industrial sector have a relatively passive involvement, although
they are involved through public comment opportunities and bear the economic
burden. In contrast, the EPA's indoor air research program includes active
participation of the public, industry, federal, state and local governments,
and many different professional associations.
The information and guidance produced by indoor air research will be
judged in terms of its ability to reduce indoor pollutant exposures. There-
fore, technology transfer is an important part of the EPA indoor air research
program. Information on some indoor air health risks is already sufficiently
advanced that public notification of risks and mitigation procedures has begun.
An example of this is the issue of environmental tobacco smoke, as discussed in
the report of the Surgeon General. The radon situation is another example.
Sufficient information is not yet available on many pollutants, such as volatile
organic compounds, to warrant the dissemination of the health risk information
to the public. The potential health risks of these pollutants is an area of
active research.
Neither SARA nor any other legislative provision of EPA authorizes the
establishment of a regulatory program to address indoor air quality. Therefore,
EPA's indoor air research program is not intended to directly support the
special purpose indoor air regulatory programs that have been authorized by
Congress (e.g., the Asbestos Hazard Emergency Response Act of 1987, which
amends the Toxic Substances Control Act). Indoor air research is directed
toward the identification and characterization of serious public health risks
in the indoor environment, and the provision of practical information that can
be used by the public to avoid or mitigate these risks.
Such information is expected to be of considerable utility to the public,
because the costs and benefits associated with indoor risks are largely
internalized, unlike the situation with outdoor air. This means that those
experiencing effects in indoor environments are likely to have greater control
over the pollutant sources and are more likely to incur the costs and enjoy the
benefits of any mitigation efforts. Although this relationship does not hold
true in all cases, it does mean that, given appropriate and useful information,
those responsible for indoor environments are expected to voluntarily take
practical steps to reduce their risks from indoor air.
August 1989
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Many of the strategies for controlling indoor exposures involve simple,
low cost efforts. For example, awareness of the health risks associated with
environmental tobacco smoke can result in lowered exposures as a consequence of
voluntary steps to reduce smoking. Also, simple maintenance and cleaning can
reduce or eliminate many sources of biological contaminants. In other cases,
it is apparent that more can be done to reduce overall exposures and risks by
altering building designs and ventilation patterns than by approaching the
problem source-by-source or pollutant-by-pollutant. Risks from exposures to
many consumer products can be reduced by following label instructions and
assuring that ventilation is adequate during use. An important role for EPA's
indoor air research program is to bring these low cost control options to the
attention of the oublic.
August 1989
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C. RADON
A major research effort conducted under SARA Title IV and continuing
under the Indoor Radon Abatement Act (TSCA Amendments) involves the assess-
ment and control of radon in indoor environments. The Federal research and
development radon program on health effects is the responsibility of the
Department of Energy; research on radon mitigation is conducted by EPA.
Section 118(K) of SARA requires a separate report to Congress on the EPA radon
mitigation research program, therefore this Indoor Air Research Needs Statement
includes all aspects of the Federal indoor air quality research program exclu-
sive of radon. While the radon research effort is not covered herein, certain
similarities between radon and other indoor pollutants are recognized. Assess-
ment of pesticide vapors entering indoor environments in soil gas and control
of particles similar to radon progeny are two examples of where the research
efforts are complementary. The reader is encouraged to review the 1988 Report
to Congress on the Radon Mitigation Demonstration Program for a full discussion
of EPA's radon research needs.
August 1989
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D. SUMMARY OF RESEARCH NEEDS
Congress requested that EPA undertake a comprehensive indoor air research
program, including the coordination of government and private sector efforts.
The research needs discussed in this report reflect the coordination of the
activities of these organizations. For the purposes of identifying indoor air
research needs, the federal agencies involved with indoor air research have
identified research activities in the following "need" categories:
Risk assessment methodology needs, which focus on health and hazard
identification, dose-respcnse assessment, exposure assessment, and
risk characterization frameworks and methods, especially as they
relate to the comparability of results from oral versus respiratory
toxicity studies
Exposure assessment and modeling needs, including methods develop-
ment and evaluation, measurement studies, development of predictive
models and the management of measurement data
Source-specific needs which emphasize indoor combustion sources, such
as tobacco products and indoor combustion appliances; building
materials and furnishings; activity sources that emphasize product
use and storage; and transportation and ambient sources of urban
pollutants
Building system needs which emphasize studies of infiltration and
ventilation in both large and small buildings
Control techniques aimed at specific sources of indoor pollutants and
ventilation strategies
Crosscutting research needs, including research devoted to the
study of the impact of indoor air quality on productivity
Technology transfer and support to state and local governments and
the private sector.
The following table summarizes the major indoor air research needs in
these categories, and attempts to give a sense of agency involvement, timing,
and priority. Priority is based upon an immediate need to protect public
health, the needs of state and local governments and the public, and the needs
of the environmental research community to properly assess preliminary
research results, especially the health significance of indoor pollutant
exposures.
August 1989
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SUMMARY OF MAJOR INDOOR AIR RESEARCH NEEDS1
RESEARCH AREA
AND STUDY DESCRIPTION
AGENCIES
AND ORGANIZATIONS
INVOLVED
PROJECT
TIME (YRS)
PRIORITY2
A. RISK ASSESSMENT METHODOLOGY FRAMEWORK
1. Risk Assessment Methods
* Develop risk methodology procedures and perform assessments for
major indoor air pollution scenarios, and conduct additional
toxicological research vis-a-vis evaluation of respiratory hazards
2. Special Reports and Hazard Identification
* Prepare special reports evaluating biological contaminants, odors
and annoyance levels, and the effects of cleaning and maintenance
on indoor air quality
3. Supporting Information for Risk Assessment
* Provide support for development and maintenance of data bases
EPA/CPSC/DHHS/ 4
STATES/PRIVATE SECTOR
EPA/CPSC/DHHS/ 5
DOE/PRIVATE SECTOR
EPA/DHHS/DOE/PRIVATE 5
SECTOR
PRIMARY
SECONDARY
PRIMARY
B. EXPOSURE ASSESSMENT AND MODELING
1. Monitoring and Measurement
* Improve sampling and analytical techniques for volatile and semi-
volatile organic compounds
* Develop improved screening protocols, questionnaires, and measurement
methods for complaint-building studies
* Develop improved screening protocols, questionnaires, and measurement
methods for indoor air quality studies in residences
* Evaluate and validate new measurement methodologies under field
conditions for aerosols, organics, biological species, and air
exchange rates
* Develop validation procedures to improve accuracy of information
collection (such as questionnaires and activity diaries)
2. Modeling
* Further develop and validate spatial/temporal models, source models,
receptor models, and exposure models for indoor environments including
transportation compartments
EPA/DHHS/DOE/NIST
EPA/DHHS/DOE/STATES
EPA/CPSC/PRIVATE
SECTOR
EPA/CPSC/DHHS/DOE/
PRIVATE SECTOR
EPA/DHHS/DOE/PRIVATE
SECTOR
EPA/CPSC/DHHS/DOE/
STATES/PRIVATE SECTOR
PRIMARY
PRIMARY
SECONDARY
PRIMARY
SECONDARY
SECONDARY
Research needs to be conducted by both the public and private sectors.
2Primary research projects are those projects that need to be initiated immediately to provide important information to protect public
health or to begin more in-depth research. Secondary status research projects are also necessary projects that will begin after an
evaluation of preliminary research results, or as soon as research facilities, staff and funding become available.
-------
SUMMARY OP MAJOR INDOOR AIR RESEARCH NEEDS1 (continued)
RESEARCH AREA
AND STUDY DESCRIPTION
AGENCIES
AND ORGANIZATIONS
INVOLVED
PROJECT
TIME (YRS)
PRIORITY2
3. Data Management and Quality Assurance
* Implement and maintain a source emissions data base incorporating
source characteristics associated with emission factors
* Develop standard reference materials for measurement of indoor
pollutants
* Implement and maintain an indoor air quality data repository
EPA/CPSC
NIST/EPA
EPA/CPSC/DHHS/DOE/
STATES/PRIVATE SECTOR
PRIMARY
PRIMARY
PRIMARY
C. SOURCE-SPECIFIC NEEDS
1. Combustion Sources
Environmental Tobacco Smoke (ETS)
* Characterize and model ETS exposure to children
* Develop ETS exposure dosimetry methods
* Evaluate cancer risks from ETS exposure
* Study the non-cancer effects from ETS exposure
Indoor Combustion Appliances
* Characterize emissions from kerosene heaters
* Prepare exposure assessment of kerosene heater, gas-
space heater, wood stove, and unvented gas stove emissions
* Dosimetry - Develop physiologically-based dose-response models
and biological markers
* Cancer risks - Conduct epidemiology feasibility study and
perform in vitro and jin vivo genetic and carcinogenic
bioassays
* Non-cancer health risks - Prepare screening studies for hazard
identification, multidisciplinary assessments, and verify the
accuracy of the predictive exposure, dose, and health effects
models '
2. Material Sources
* Measure emission rates of organic chemicals from building
materials, furnishings, and consumer products
* Conduct comparisons of emissions from selected materials in
small chambers, large chambers, and test houses
* Characterize the human response produced by emissions from selected
materials
* Evaluate health effects of substitute products and materials
DHHS/EPA
DHHS/EPA
OHHS/EPA
DHHS/EPA
CPSC/EPA/PRIVATE
SECTOR
CPSC/EPA/PRIVATE
SECTOR
EPA/DHHS/PRIVATE
SECTOR
EPA/OHHS/STATES
EPA/DHHS/STATES
PRIVATE SECTOR
EPA/CPSC/DOE
EPA/CPSC/PRIVATE
SECTOR
EPA/DHHS/STATES
EPA/DHHS
PRIMARY
PRIMARY
PRIMARY
PRIMARY
PRIMARY
PRIMARY
SECONDARY
SECONDARY
SECONDARY
PRIMARY
PRIMARY
PRIMARY
PRIMARY
Research needs to be conducted by both the public and private sectors.
2Primary research projects are those projects that need to be initiated immediately to provide important information to protect public
health or to begin more in-depth research. Secondary status research projects are also necessary projects that will begin after an
evaluation of preliminary research results, or as soon as research facilities, staff and funding become available.
-------
SUMMARY OF MAJOR INDOOR AIR RESEARCH NEEDS1 (continued)
RESEARCH AREA
AND STUDY DESCRIPTION
AGENCIES
AND ORGANIZATIONS
INVOLVED
PROJECT
TIME (YRS)
PRIORITY2
3. Activity Sources
* Develop measurement methods and generate emission factors for
activities associated with personal care, maintenance, office work,
leisure, and transportation
* Characterize electrical, magnetic, and electromagnetic fields
encountered in personal and work-related activities
* Determine the health effects and mechanisms of interaction with
electromagnetic fields
* Characterize indoor exposures to consumer-applied pesticides
(and other toxicants)
4. Ambient Sources
Outdoor Air
* Characterize indoor/outdoor concentration relationships for
input to exposure models (e.g., heavy metals, ozone, and
biological contaminants)
Soil
* Characterize the penetration of soil-related pollutants into the
indoor environment and perform a risk assessment
Water
* Characterize exposures to volatile organic compounds released
from water
* Investigate contribution of tap water in home humidifiers to indoor
pollutant levels
5. Biological Contaminants
* Prepare report on health effects, state-of-the-art sampling
methods, and research needs
* Initiate development of standardized monitoring methods
* Hardware development for biological monitoring methods
* Identify and establish baseline concentrations of major classes of
biological contaminants
* Investigate contribution of HVAC equipment to indoor levels of
biologicals
EPA/CPSC/DHHS
DOE/DHHS/EPA/PRIVATE
SECTOR
DOE/DHHS/EPA/PRIVATE
SECTOR
EPA/PRIVATE SECTOR
EPA/DHHS/STATES
EPA/STATES
EPA
EPA/CPSC
EPA/CPSC/DHHS/PRIVATE
SECTOR
EPA/CPSC/DHHS/PRIVATE
SECTOR
EPA/CPSC/DHHS/PRIVATE
SECTOR
EPA/CPSC/DHHS/PRIVATE
SECTOR
EPA/CPSC/DHHS/DOE/
STATES/PRIVATE SECTOR
3
3
2
3
2
4
4
PRIMARY
SECONDARY
SECONDARY
PRIMARY
SECONDARY
SECONDARY
SECONDARY
PRIMARY
PRIMARY
PRIMARY
SECONDARY
PRIMARY
PRIMARY
'Research needs to be conducted by both the public and private sectors.
2Primary research projects are those projects that need to be initiated immediately to provide important information to protect public
health or to begin more in-depth research. Secondary status research projects are also necessary projects that will begin after an
evaluation of preliminary research results, or as soon as research facilities, staff and funding become available.
-------
SUMMARY OF MAJOR INDOOR AIR RESEARCH NEEDS1 (continued)
RESEARCH AREA
AND STUDY DESCRIPTION
AGENCIES
AND ORGANIZATIONS
INVOLVED
PROJECT
TIME (YRS)
PRIORITY2
D. CONTROL TECHNIQUES
1. Source-Specific
* Evaluate effectiveness of source modifications, including changes
in product composition or use, conditioning of building materials
before use, and product substitution
2. Air Cleaning
* Conduct laboratory and field studies to determine the effectiveness
of air cleaners for the control of indoor pollutants
EPA/CPSC/DOE/STATES/ 5
PRIVATE SECTOR
EPA/CPSC/DOE/NIST/ 3
PRIVATE SECTOR
PRIMARY
PRIMARY
E. BUILDING SYSTEMS
1. Ventilation
* Continue research to refine tracer gas techniques for measuring
ventilation
* Develop ventilation measurements that can be widely applied
* Continue research devoted to laboratory measurements of ventilation
* Develop techniques and protocols to measure ventilation effectiveness
2. Field Measurements
* Measure ventilation rates and ventilation effectiveness in complaint-
building investigations and residences
3. The Total 'Building System
* Conduct prototype integrated assessments of the combined impacts of
source emissions, pollutant levels, ventilation rates, and energy
consumption in new building designs and perform follow-up measure-
ments
DOE/DHHS/EPA/NIST/
PRIVATE SECTOR
EPA/DOE/DHHS/NIST/
PRIVATE SECTOR
DOE/EPA/PRIVATE
SECTOR
NIST/EPA/DOE/DHHS/
PRIVATE SECTOR
EPA/CPSC/DHHS/DOE/
NIST/PRIVATE SECTOR
EPA/CPSC/DHHS/DOE/
NIST/PRIVATE SECTOR
3
4
4
5
SECONDARY
PRIMARY
SECONDARY
PRIMARY
PRIMARY
PRIMARY
'Research needs to be conducted by both the public and private sectors.
2Primary research projects are those projects that need to be initiated immediately to provide important information to protect public
health or to begin more in-depth research. Secondary status research projects are also necessary projects that will begin after an
evaluation of preliminary research results, or as soon as research facilities, staff and funding become available.
-------
SUMMARY OF MAJOR INDOOR AIR RESEARCH NEEDS1 (continued)
RESEARCH AREA
AND STUDY DESCRIPTION
AGENCIES
AND ORGANIZATIONS
INVOLVED
PROJECT
TIME (YRS)
PRIORITY2
CROSSCUTTING RESEARCH
* Conduct an epidemiologic study of the impact of indoor air quality
on productivity
* Conduct studies regarding the prevalence of building-occupant
symptoms and indoor pollutant levels
* Conduct ergonomic and psychosocial research
EPA/CPSC/DHHS/DOE/
NIST/STATES/
PRIVATE SECTOR
DHHS/EPA/STATES/
PRIVATE SECTOR
DHHS/EPA/PRIVATE
PRIMARY
SECONDARY
SECONDARY
G. TECHNOLOGY TRANSFER
FEDERAL AGENCIES/STATES/
PRIVATE SECTOR
PRIMARY
Research needs to be conducted by both the public and private sectors.
2Primary research projects are those projects that need to be initiated immediately to provide important information to protect public
health or to begin more in-depth research. Secondary status research projects are also necessary projects that will begin after an
evaluation of preliminary research results, or as soon as research facilities, staff and funding become available.
-------
II. RESEARCH NEEDS
A. RISK ASSESSMENT
The ultimate goals in addressing indoor air quality problems are to
characterize and understand the risks to human health which indoor pollutants
pose and reduce those risks by reducing exposures through non-regulatory
mitigation approaches.
Indoor air quality has become a concern, because indoor pollutant levels
frequently exceed outdoor levels, and individuals may spend 80 to 90% of their
time in residences, buildings, and in closed transit. While we have expended
much effort over the past 20 years to assess and manage outdoor pollutants, the
identification and assessment of hazardous indoor air pollutants have only
recently begun.
The major categories of indoor pollutants can be related to mortality,
morbidity, and reduced productivity. The most potentially hazardous pollutants
are shown below.
INDOOR AIR QUALITY HAZARDS
Pollutant Mortality Morbidity Productivity
1.
2.
3.
4.
5.
6.
7.
ETS
Radon
Asbestos
Organ ics
Biologicals
Inorganics
Non- Ionizing Radiation
#
*
#
#
#
#
#
#
#
#
#
#
$
$
$
$
The characterization of risk from these pollutants varies in relation to
understanding their sources, exposures, and dose-response information. The
most well known indoor "air pollutants originate from a variety of sources.
These sources generate wide ranges of the pollutant concentrations over time.
Actual human exposure to many of these pollutants is at this time not well
understood. Exposure assessment is one of the indoor air research community's
most important research activities.
Although far from being complete, our knowledge of concentration-response
relationships for some indoor air pollutants, those which are also outdoor or
occupational-setting pollutants, is quite extensive. Health consequences of
August 1989 11
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exposures to carbon monoxide, nitrogen dioxide, fine particles (i.e., less than
2.5 pin), radon, and even asbestos are predictable because of the many years of
study of these substances in either the ambient environment or occupational
settings. However, even for these pollutants, we often lack knowledge of their
effects when combined with other pollutants. For example, fine particles in
environmental tobacco smoke (ETS) are not toxicologically identical to fine
particles from a kerosene heater or a humidifier.
For many indoor air pollutants such as the biological contaminants,
individual gas-phase organics (both single compounds and mixtures), and
non-ionizing radiation, our knowledge of the health consequences associated
with indoor exposures is extremely limited.
Recently, risk characterizations have been made for a very few specific
indoor air pollutants. Annual excess mortality in the range of 5,000 to
20,000 cases per year has been estimated for radon. Also, environmental
tobacco smoke may be associated with 500 to 5,000 excess cancer deaths for
nonsmokers annually.
Though it is difficult to adequately quantify the risks of many indoor air
pollutants, it is expected that more risk occurs indoors simply because more
time is spent indoors. This is especially true for many of the "hazardous air
pollutants" for which much attention has been directed in the ambient environ-
ment over the past decade.
One of the biggest deficiencies highlighted in the EPA's preliminary
assessment of indoor environments is the inability to properly assess human
risk from indoor air pollution. This shortcoming is the result of limited data
on human exposure to the many different pollutants found indoors and the
inability to distinguish among multiple health endpoints. Consequently, one of
the highest research objectives is to develop data and information with which
to better characterize exposure and health effects to determine risk.
Risk characterization is a primary objective of Title IV. The following
are basic research needs that are intended to respond to this Congressional
requirement.
1. Framework for Assessing Risk
The process of estimating the harmful effects of indoor air pollution is
accomplished through risk assessment. The assessment of risk entails:
(1) hazard identification, (2) exposure assessment, and (3) dose-response
assessment. Risk characterization involves pulling together all relevant
health information to quantify or qualify the risks associated with various
indoor air scenarios.
The majority of research needs mentioned in this report are intended to be
applied in the risk assessment process. The risk assessment process is well-
defined and is driven by widely accepted scientifically-based guidelines. One
essential research need is the application of the risk assessment guidelines to
different indoor air pollution scenarios and situations.
August 1989 12
-------
Risk assessment fully utilizes the data collected in indoor studies. To
achieve the best results, the risk assessment framework should embody the
traditional risk model chain: sources, transport and fate, exposure, dose, and
effect. This framework would be best applied in multiple iterations rather
than in a "single pass" to take full advantage of new data. To fill this need
quantitatively, a seven step methodology is being designed and will be used
with a number of indoor air pollution scenarios.
As shown graphically beiow, the purpose of step one is to survey what is
known about a pollutant and its sources. Step 2 investigates possible health
or welfare effects, while step 3 identifies a number of components including
source factors, concentration distributions, exposure times, and populations
at risk. Step 4 quantifies these components and their uncertainties, and
step 5 involves the derivation of a deterministic risk equation. Step 6
tests the risk equation under varying assumptions and situations, and the
final step examines the risk assessment and identifies ways to better
integrate research results so that the risks can be more readily compared
and better estimated in another iteration of the process.
RISK ASSESSMENT METHODOLOGY
SUp 1 DETERMINE IAQ POLLUTANTS
SUp 2 INVESTIGATE EFFECTS
SUp 3 DEVELOP RISK METHODOLOGY
SUp 4 QUANTIFY UNCERTAINTIES
SUp B APPLY RISK EQUATIONS
SUp 6 QUANTIFY IAQ RISKS
SUp 7 RISK ASSESSMENT PROCESS
EVALUATION
Seven-step risk characterization methodology
August 1989
13
-------
Since the goal of the EPA indoor air research effort is to support non-
regulatory approaches to mitigating potential indoor health risks, the quanti-
fication requirements of risk assessment are somewhat relaxed. While it is
important to quantify the relative risks both among indoor pollutant exposures
and as compared with those associated with ambient pollutant exposures, the
calculation of risk need only be sufficient to estimate the benefits from
different risk management approaches.
2. Special Topics for Assessing Risk
An adequate assessment of risk is a complex and far reaching process.
There *re many unstudied sources of pollutants found indoors which may
contribute to the human health risk and need to be better understood so they
can be factored into the the risk assessment process. Some of these include
cleaning methods and practices, biological organisms originating from humans
and animals and from excess moisture situations, and sources of odors. EPA is
currently preparing a series of reports to provide information on these special
topics.
3. Supporting Information for Risk Assessment
Data and information that support the assessment of risk must be properly
maintained, updated, and distributed. This type of support includes the
establishment of a clearinghouse for scientific information and maintenance of
a bibliographic data base.
August 1989 14
-------
B. EXPOSURE ASSESSMENT AND MODELING NEEDS
An integral step in assessing risk in the indoor environment is the
determination of the exposure distributions of pollutants. This can be
accomplished by making microenvironmental and exposure measurements using fixed
location and personal exposure monitors, or by estimating these exposures using
limited empirical data sets and predictive models. A direct link to sources
and mitigation can then be made through indoor receptor models.
Indoor air quality models and supportive data bases are essential in
understanding the nature and magnitude of indoor air quality. Reliance on
monitoring efforts alone to provide information on the number of pollutants and
building types is prohibitively expensive. The research community must
continue to develop models that will simulate pollutant sources and building
factors affecting indoor air quality. These models can then be used to
quantify exposure reductions expected from different mitigation options, and
serve as an important tool for public and private building investigators to use
in identifying and solving problems.
The following is a list of assessment tools which must be refined if
characterization and control of indoor pollutants are to be achieved.
• Evaluation of sampling and analysis for organic pollutants
• Improvement of measurement methodologies for polar organic
compounds
• Improvement of measurement methodologies for biological pollutants
• Development of versatile and unobtrusive indoor air quality
samplers
• Development of protocols for measuring and reporting source
emission rates for selected indoor materials and consumer products
• Development and testing of screening and source use questionnaires
• Evaluation of methods to estimate indoor pollutant exposures in
epidemiological studies
• Investigation of the composition and size distribution of indoor
particles
• Measurement of indoor spatial and temporal concentration gradients
• Development of receptor models for using field data to estimate
the contributions of various pollutant sources
• Maintenance of the indoor source emissions data base
August 1989 15
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1. Monitoring and Measurement
One way to assess an individual's exposure to indoor air pollution is the
direct measurement of pollutants in indoor microenvironments. The accuracy and
representativeness of these measurements depend on the measurement and
monitoring methods used. Indoor monitoring methodologies must consider the
obtrusiveness of the samplers and their ability to sample without altering the
microenvironmental situation. Current monitoring needs include evaluating the
ability to extend existing monitoring methods for analyzing indoor levels of
organics to an expanding list of potential contaminants, developing better
methods for measuring polar organic compounds, and developing smaller, less
obtrusive samplers for se^ivolatile organics and analytical techniques to
separate organic vapor and particle phases. Miniature, real-time analyzers are
needed to provide exposure distribution information for pollutants such as
nitrogen dioxide (N02) and gas-phase organic compounds or volatile organic
compounds (VOCs). Low cost monitors must be developed so that large scale
studies can be undertaken and individual homeowners can afford testing. Such
monitors are often small, passive devices that can be worn on the person.
Health and comfort complaints among building occupants have become more
prevalent as the public becomes better informed about indoor air pollution.
Better screening techniques are needed to provide rapid response and broad-
scale coverage of pollutant classes. Standardized protocols for resolving SBS
complaints must be developed and tested for use by local agencies and private
contractors. To standardize procedures, a compendium of methods must be
developed and maintained so that measurements made by various investigators are
accurate, consistent, and comparable.
After monitoring methods are developed, they must be field tested.
Research needs include evaluation of new monitoring methods for semi volatile
organic compounds (SVOCs) and study of their chemical identity and fate
indoors. Data bases must be examined to relate sources to marker elements and
compounds through receptor models. Measurement methods for biological contam-
inants are needed. New indoor aerosol monitoring methods must be evaluated to
determine their consistency with ambient methods.
Measurements are needed to determine the exposure distributions of
selected SVOCs to better estimate risk for the more toxic pollutants found
indoors. Sources of SVOCs include combustion appliances, ETS, and furnishings.
SBS protocols and measurement techniques must be applied to selected situations
to better understand the nature and magnitude of SBS complaint situations.
Special studies are also needed to delineate the risk of using humidifiers and
their dissemination of minerals and biological species. Monitoring studies are
needed to better understand the gas-phase organic compound contributions of
solvents used in personal hobbies, offices, and maintenance activities.
A multi-purpose indoor air questionnaire must be developed for use in
future indoor air investigations. This questionnaire must be validated for
accuracy and completeness, easy to administer, machine readable, and must
provide responses and summaries that are directly relatable to corresponding
exposure, source, and analytical data. Uniform activity diaries (personal and
source) must also be made available to the scientific community to facilitate
comparability of study data.
August 1989 16
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2. Modeling
Models can be used to rapidly and economically assess indoor problems.
Once validated, models often provide acceptably accurate estimates of indoor
pollutant levels. EPA has developed an IAQ model for personal computers that
couples indoor sources with building air exchange, room-to-room transport, HVAC
operation, and air cleaners to predict indoor concentrations of specific
pollutants. Another promising indoor model under development is the CONTAM
model developed by the National Institute of Standards and Technology for EPA,
DOE, and CPSC. CONTAM is a full-scale, multi-zone building contaminant dis-
persal model that simulates flow processes (e.g., infiltration, dilution, and
exfiltration) and contaminant generation, reaction, and removal processes. In
addition macromodeling research sponsored by CPSC and DOE may provide
generalized population exposure distributions. Research is needed to validate
these models using actual measurements under controlled situations. User-
friendly computer programs are needed to facilitate their use beyond the
research setting.
Exposure estimation involves the use of predictive models. Research needs
include better information on activity patterns and the development of
colocated exposure and microenvironmental data bases to permit validation of
the models and linking them to sources and mitigation strategies. The
incorporation of biomarkers within exposure models must be pursued to permit
more accurate assessments of potential health risks from indoor pollutants.
Additional information is needed on the distribution of pollutant exposures to
help develop selection criteria for sampling.
3. Data Management and Quality Assurance
The development of centralized repositories of indoor data is needed to
better analyze data from various researchers. Personal exposure, microenviron-
mental, ambient, source emission, and analytical results should be uniformly
maintained in central repository. These systems must be easily accessible by
federal, state, and local agencies, and must include precise and accurate
information. The indoor air quality field studies data base maintained for the
Gas Research Institute, the Electric Power Research Institute, and DOE is an
example of such a data base.
Quality assurance efforts specific to indoor measurements are needed to
provide standard methodologies for use by researchers. Examples include the
development of standard VOC mixtures and standards for SVOC, ETS, and bio-
logical contaminant analyses.
August 1989 17
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C. SOURCE-SPECIFIC NEEDS
To properly characterize the indoor air environment, it is important to
understand the primary sources of indoor pollutants. Indoor sources produce
the pollutants that cause health effects, and control of these sources is the
most direct mitigation approach. There is a large variety of potential
pollutant sources in the ordinary American household and office building.
Common sources include heating and air conditioning systems, cooking and
heating appliances, building materials, biological contaminants, household
products, electric and magnetic fields, and infiltration of outdoor pollutants.
Indoor air quality is influenced by the nature and strength of pollutant
sources and sinks. In turn these sources and sinks are influenced by a number
of factors. Sources may emit pollutants at a single point or over a wide area
either continuously or episodically. Source strength may depend on human
activity such as smoking or cooking or meteorological conditions such as
temperature, humidity, wind speed, or season. The type and age of the
building, building materials, and furnishings may also be contributing factors.
Many of the above considerations also apply to sinks. Typical sinks include
sorption on interior surfaces, chemical reaction, and replacement with outside
air.
Research oriented toward specific sources of exposure and individual
pollutants is a central focus of the federal indoor air research program. This
research is necessary to assure that important indoor air risks are not over-
looked, and to focus continued emphasis on known risks. This research will
provide a vehicle for the assessment of known high-risk categories, such as
ETS, as well as suspected high risk categories such as biological contaminants,
combustion appliances, and building materials and products.
For purposes of organizing research and assuring that all indoor air risks
are considered in a methodical manner, the following source categories have
been established.
1. Combustion Sources - environmental tobacco smoke, indoor combus-
tion appliances
2. Material Sources - building materials, furnishings, work and
leisure materials, replacement materials, product storage
3. Activity Sources - maintenance and cleaning supplies, domestic
water, pesticides, transportation
4. Ambient Sources - air, soil, water
5. Sources of Biological Contaminants - animal and human sources of
bacteria, viruses, and allergens.
1. Combustion Sources
Prominent among the concerns of indoor combustion sources are environ-
mental tobacco smoke, unvented gas stoves and heaters, kerosene heaters, and
wood burning stoves, furnaces, and fireplaces.
August 1989 18
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Although cigarette smoking Is well established as the largest single
preventable cause of premature death and disability in the United States, the
1986 Surgeon General's report, "The Health Consequences of Involuntary Smoking"
was the first U.S. Government report to establish a significant health risk
from exposure to ETS. The quantitative estimates of the cancer risk alone as
reviewed by this and the National Academy of Sciences, 1986 report suggest that
ETS poses a very significant risk to the U.S. population. Consideration of the
magnitude of the exposure to ETS indoors and the time individuals spend indoors
has led scientists to suggest that it is a major and possibly the single
largest source of exposure to particles, organics, and mutagens. Several
studies are underway to determine the human exposure and potential cancer risk
from exposure to ETS. Overall, research is providing 'nformation so that the
public, local, state, and federal government agencies, the building industry,
employers, and others can make well informed choices regarding the control of
exposure to ETS.
Some of the pollutants associated with wood stoves, furnaces, and fire-
places, and unvented heating and cooking appliances are regulated under the
Clean Air Act. These pollutants include N02, sulfur dioxide (S02), carbon
monoxide (CO), and particulate matter. While EPA has the authority to regulate
"ambient air," CPSC has the authority to regulate emissions from appliances
that contribute to poor indoor air quality.
Considerable progress has been made in developing personal monitors and
characterizing exposures to combustion pollutants in indoor microenvironments
(notably for N02 and CO). There has also been considerable research to assess
the health effects associated with these pollutants and of some polycyclic
aromatic hydrocarbons (PAHs). However, there is very little knowledge about
the comparative (or actual) health risks of commonly used combustion
appliances. Thus, further research is necessary to determine the magnitude of
the health risks from those sources. Recent data from studies of kerosene and
unvented gas space heaters indicate the need for continued examination of
potential exposures from these products. The implications of acute and chronic
respiratory health effects are potentially very important.
Studies are needed to evaluate the non-cancer health effects of combustion
appliance emissions indoors. This issue is important because approximately
7 million homes have kerosene appliances, 4.2 million homes use unvented gas
space heaters, and 20 million homes have gas stoves. Studies are needed to
investigate the health effects associated with the acute and intermittent
inhalation of the whole and fractionated effluents generated from home heating
units and other combustion appliances.
Environmental tobacco smoke
Environmental tobacco smoke consists of at least four thousand compounds,
some of which have toxic or carcinogenic properties. The Varge emission rate
of fine mode particles from tobacco smoke has led researchers to conclude that
ETS is the dominant source of these particles indoors. Although not well
characterized, ETS may also pose a significant risk of non-cancer effects
ranging from irritation to chronic lung disease, especially for children.
August 1989 19
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Evaluations from the National Academy of Sciences and the Surgeon
General's Office of Smoking and Health conclude that exposure to ETS increases
the incidence of lung cancer in nonsmokers. Studies devoted to ETS
consistently show a 30% increased risk (within 95% confidence intervals) for
nonsmoking spouses of smokers.
There is enough known about the health effects of ETS to demonstrate the
need for quantitative risk assessments for cancer and non-cancer effects. The
specific research needs identified below are drawn heavily from the research
recommendations made by the NAS and the Surgeon General.
One important research need is the development and standardization of
better sampling and analytical methods to both collect and measure ETS and to
characterize the toxicologically significant components of ETS. Research is
planned to determine the distribution of constituents in the particulate and
vapor phases of ETS and to identify and evaluate marker compounds for these
phases. Short-term genetic microbioassay methods will be used in conjunction
with chemical characterization to identify mutagenic components and to continue
research to measure mutagenic emission rates and exposures. Monitoring and
modeling studies will continue to quantify emissions, transport, and fate of
ETS in indoor air environments. Chambers and test homes will be used to
determine the relationship between various factors (e.g., room size, humidity,
air exchange rate, wall coverings) on ETS exposure concentrations.
The highest priority research recommended by both the NAS and the Surgeon
General is in the area of understanding the relationship between ETS exposure
and dosimetry. This area of research is central to proposed research in
pollutant characterization and modeling. The strategy relies on the develop-
ment and use of biological markers together with personal exposure monitoring
and health effects studies. Studies are needed to improve use of cotinine (a
nicotine metabolite) as a biological marker of exposure to ETS. New highly
sensitive methods for measuring DNA and protein adducts of tobacco-specific
chemicals will be further developed and applied in pilot studies of human
fluids and tissues. These methods will also be tested in chamber and field
studies.
Research devoted to the non-cancer effects of ETS includes examination of
exposure-effects relationships for both short-term acute effects (e.g., irrita-
tion and allergic responses) and chronic effects that can lead to respiratory
or cardiovascular effects. Initial attention should be given to susceptible
populations such as children and people with preexisting cardiopulmonary
diseases.
Indoor combustion appliances
Indoor combustion appliances are known to be significant sources of indoor
pollutants including N02, CO, C02, S02, fine particles, polycyclic organic
matter (POM), VOCs, and SVOCs. Incomplete combustion products have been
associated with human cancers at many sites, particularly the lung. Combustion
products of coal, wood, and diesel fuel are mutagenic in bacteria and
tumorigenic in animal studies. Polycyclic aromatic hydrocarbons are known
animal carcinogens. The criteria pollutants, N02, CO, particles and S02, have
health effects demonstrated in humans which include pulmonary toxicity and
dysfunction, especially in sensitive populations such as asthmatics.
August 1989 20
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Gas stove usage has been associated with respiratory effects, especially
in children, including increases in pulmonary illnesses. Elevated levels of
N02 in homes can exceed the levels that cause pulmonary function changes in
some asthmatics studied under controlled conditions. The short-term and
long-term health effects on humans from exposure to the combination of
pollutants in combustion emissions in the indoor environment are not well
understood. For example, information on unvented combustion appliances
indicates that combustion emissions can cause pulmonary function changes in
asthmatics (short-term exposure) and irreversible lung changes in animals
(long-term exposure). Preliminary .studies also indicate that emissions from
some kerosene heaters may be potentially genotoxic and carcinogenic.
Limited information is available on the contribution of vented appliances
to indoor air pollution. Problems often associated with vented appliances and
poor indoor air quality include blocked flues, down drafting, corroded heat
exchange units, and maladjusted appliances. These problems can result in
severe exposures. Research is needed to determine the prevalence of these
problems and their contribution to indoor pollutant exposures.
To characterize the risks from combustion appliances, it is necessary to
know what appliance types and models are in use and how they are operated and
maintained. This information provides data for exposure assessment and gives
guidance as to which appliances should be studied as a higher priority.
Exposure assessment and health risk characterization studies are needed.
Studies of specific gases, such as N02 and CO from gas stoves, have shown that
when properly adjusted and used (e.g., not for heating), these devices operate
within a level which does not pose a serious health risk. Although significant
uncertainties exist for risk assessment of gas stoves, much is known and major
epidemiology studies are underway. Therefore, the priority for research is on
unvented combustion appliances where there is a potential concern for acute
effects, chronic lung disease, and possibly cancer, but minimal supporting
data. Other major classes of combustion (i.e., coal and wood stoves, fire-
places, and furnaces) have been studied, and do not seem to pose comparable
risk to unvented appliances.
Research is needed to characterize the chemical and physical emissions
from various indoor combustion sources. Previous studies have shown that the
use of gas stoves, kerosene heaters, and unvented gas space heaters can signi-
ficantly increase indoor N02 levels under certain use conditions. Organic
emissions (particle-bound, semivolatile organics and VOCs) have not been
characterized or monitored. Research devoted to combustion appliances should
initially emphasize unvented appliances. Research is being conducted to survey
information on appliance types and models and maintenance and usage patterns in
U.S. homes. Results from the survey will provide guidance on designing future
monitoring and health studies that are most representative of home use
scenarios. The major portion of this research will involve characterization of
the combustion emissions in chambers and test homes and modeling of human
exposures under various conditions. This research will both assist in estimat-
ing potential risks and provide information to mitigate exposures from these
sources.
August 1989 21
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Studies are also needed to determine the profile of the population at risk
(age, sex, and health status), and the magnitude, frequency, and duration of
inhalation exposure to pollutants from indoor combustion. Human exposures can
be estimated by measuring existing exposures and modeling future exposures.
Dosimetry is the quantitative relationship between exposure and dose
delivered to the target site, and thus is a critical component of quantitative
risk assessment. Dosimetry models need to relate inhaled concentrations of
combustion emissions to dose in children and people with preexisting lung
disease to determine which subpopuiations are likely to be at increased risk.
Biomarkers also need to be developed to assess biologically effective doses,
for example to DNA, since combustion emissions may have carcinogenic potential.
Biomarker methods will be valuable in future epidemiology studies.
Research is also needed to study the non-cancer risks associated with
combustion appliance emissions. Given the range of sources and potential
health effects, this research must be conducted stepwise, with each step
providing guidance in the design of the next step. Research will begin with
unvented heaters because preliminary data suggests that emissions from some
unvented heaters may present adverse health risks.
Based on the results from these preliminary characterization studies, the
range of appliances examined and the type of test conditions may be expanded.
The basic approach used in this effort will be to begin with hazard identifica-
tion and proceed to dosimetry and dose-response assessment. Prior animal
inhalation (and controlled-human) studies have concentrated on individual
pollutants. Research devoted to mixtures of combustion pollutants is needed.
As more knowledge is gained, epidemiological studies will be designed.
Results from characterization studies will also allow selection of the
appliances of concern for cancer risk assessment. Dose-response assessment is
crucial to determine the quantitative relationship between exposure and dose to
combustion pollutants and the incidence of cancers. Dose-response relation-
ships associated with indoor combustion emissions need to be obtained through
epidemiological studies in highly exposed human populations and through iji
vitro and Jji vivo cancer bioassays.
Other studies will use emissions data to develop models for predicting
combustion appliance-related hazards. Controlled studies in chambers and test
buildings will be conducted on selected combustion appliances (probably
kerosene heaters and wood burners). Avenues of health research initiated
during the screening stage will then be expanded (i.e., lung irritancy, lung
immunotoxicity, neurobehavioral impacts, and mutagenicity). Controlled studies
in chambers and test buildings will be conducted to evaluate selected
appliances under varied conditions of use and physical environments. Appliance
design and use factors will be investigated.
The primary focus of each study in this area is dosimetry and identifica-
tion of the factors that contribute to the potential for increased exposure,
uptake and distribution, and disposition of the inhaled emission components.
While every emission component cannot be evaluated, studies will be conducted
to identify suspect toxicants and/or tracer elements within whole emissions,
which will contribute to both the health effects research effort and dosimetry
models.
August 1989 22
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2. Material Sources
Building materials, furnishings, and household chemicals can be
significant sources of indoor air pollution. These sources are frequently
included under the heading of "material sources." Research is needed to study
the emission characteristics of material sources and the factors which affect
these emissions. Material sources to be studied include pressed wood products,
insulation, ceiling tiles, wall coverings, adhesives, caulks, paints, and
stains; furniture, draperies, carpeting, and office partitions; and pesticides,
waxes, polishes, cleansers, room fresheners, and stored materials.
Building materials and furnishings are known to be sources of toxic
substances. For example, asbestos fibers from insulation and ceiling tiles are
widely recognized as important indoor air pollutants in schools, office
buildings, and many private residences. Formaldehyde emissions from pressed
wood products and urea formaldehyde foam insulation (UFFI) have been
extensively studied. Numerous field investigations in new and complaint
buildings have shown levels of organics well in excess of outdoor concentra-
tions. Except for formaldehyde, however, limited data are available on the
sources and health effects of organic compounds found in the indoor environ-
ment. A comprehensive research program is needed to develop an understanding
of the health risks associated with organic emissions from materials and
products commonly found in residential and commercial buildings.
Sources of indoor air pollution from stored materials include solvents and
household and commercial products. Data are available on the classes of
compounds emitted from common solvents and on many of the specific compounds
emitted from petroleum based solvents. Limited data on household solvent usage
are available from the EPA Office of Toxic Substances which emphasizes
chlorinated solvents.
Information is needed on the stored material (solvent) composition, the
classes of compounds emitted, and the specific compounds emitted. Data on
emission factors are required for both total organics and targeted individual
compounds, based on the type, age, and condition of the storage container
(including type and condition of the container cap or seal). Information is
needed on: (1) the effect of container type, condition, and age on emission
rates, (2) the effect of container seal or cap type and condition on emission
rates, (3) the impact of temperature, humidity, air exchange, product use, and
product age on emission factors, and (4) source characteristics (e.g.,
composition, compound vapor pressure, reactivity) that affect emission factors.
Data are also needed on the amount of material manufactured, sold, used, and
stored, storage location, and storage time.
The exposures of interest from these materials are those which continu-
ously occur during day-to-day occupancy, as opposed to the exposures experi-
enced during use or application. (The latter exposures are addressed later
under "Activity Sources.") Many products, such as adhesives, caulks, paints,
waxes, and polishes, have large initial emission rates of highly volatile
compounds followed by lower rates for the less volatile organic species.
The evaluation of the health effects from material sources is important,
but the direct approach of examining the health effects of every potential
major source is not feasible due to the costs involved. Rather, it is
necessary to take a more generic approach with limited evaluations of specific
August 1989 23
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chemicals or specific sources. Priority should be given to those sources
identified as causative factors of complaint buildings and longer-term health
effects.
Monitoring surveys of homes and public buildings worldwide indicate that
an assortment of volatile organic compounds is present in indoor environments.
Although the levels of individual VOCs found are generally orders of magnitude
below the Threshold Limit Values or levels considered to be harmful for any
individual compound in occupational settings, complaints associated with VOCs
do occur and little is known about the toxicity of complex mixtures. Among the
VOCs found are acetone, formaldehyde, methyl ethylketone, hexane, toluene, and
xylene (used in building materials, furnishings, and adhesives) and benzene
(emitted from gasoline). Chlorinated hydrocarbons frequently found include
methylene chloride (paint strippers), trichloroethane (paint), perchloro-
ethylene (dry-cleaned clothes), trichloroethylene (type correction fluid and
degreasing agents) and paradichlorobenzene (deodorizers and insect repellents).
Some of these VOCs (e.g., benzene) are known to be carcinogenic. Many of the
individual VOCs such as n-hexane and toluene are known to be neurotoxic, but at
levels much higher than those found typically indoors. Complaints of
irritating air quality in homes and office buildings have given rise to the
term sick building syndrome. This syndrome includes a large number of neuro-
behavioral and respiratory complaints, including mental fatigue, headache,
dizziness, nausea, irritation of eye, nose and throat, hoarseness of voice,
wheezing, dry mucous membranes and skin, erythema, airway infections, cough,
and nonspecific airway hyperreactivity reactions.
Research emphasis needs to be placed on developing and conducting appro-
priate tests to objectively assess the health effects associated with these
exposures. Monitoring methods and instruments need to be designed to measure
organic species at low levels. Source emission rates need to be determined,
and source models developed to evaluate the effect of air temperature,
humidity, and air exchange rate on emissions. Other source characteristics
that affect emission rates (e.g., composition, compound vapor pressures,
reactivity, etc.) also need to be evaluated. Control strategies which need to
be investigated include product modification, material substitution, and
modification of the ventilation system. For example, the effectiveness of
increased temperature (during unoccupied hours) and increased ventilation
following initial building construction needs to be studied. Health effects
and source characterization studies need to be performed using exposure
chambers. Field measurements in a test home need to be conducted to evaluate
monitoring instruments and to integrate health effects, monitoring, and source
characterization studies. Ultimate verification of findings will rely on field
studies in residences, offices, and public access buildings.
The information developed in this research program is needed by builders,
architects, engineers, contractors, manufacturers, homeowners, building owners
and managers, public officials, researchers, and the general public. The
following outputs are anticipated:
Emission testing procedures useful for developing emission rate
and organic vapor composition data for building materials and
consumer products. Such procedures would be useful to manufac-
turers for determining the emission characteristics of their
products and passing such information on to their customers.
August 1989 24
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Monitoring methods for organics applicable to the low concentra-
tions encountered in buildings. These methods would be useful
to those investigating indoor air quality problems, including
complaint buildings.
Health effects testing methods for evaluating acute and chronic
health end points. Such methods would be used by researchers
and the medical community to determine the health hazard associ-
ated with materials, furnishings, and consumer products.
Emission factors for a variety of materials and consumer prod-
ucts. This information would allow architects and builders to
design and construct buildings with inherently low organic
emission characteristics. Homeowners, landlords, and the
general public would be able to select products with low emis-
sion characteristics.
Relative health hazard rankings of materials and consumer
products. All parties would use such information to select and
use products with minimum health hazard. Public officials might
use these rankings to develop product standards (e.g., HUD
requirements for particleboard formaldehyde emissions in mobile
homes) or influence local building codes (e.g., prohibition of
asbestos or UFFI).
Emission models for indoor material sources. Simple models for
predicting the emission rates from sources as a function of
environmental variables (e.g., temperature, relative humidity,
air exchange rate) would be used in "whole building" models to
calculate the expected concentration of various pollutants in
the indoor environment. Data on the "sink effect" of materials
and furnishings is also required.
Information on emission control strategies and alternatives.
Architects and builders would use indoor air quality controls to
ameliorate complaint building problems and to design and
construct buildings to minimize indoor air quality problems.
Homeowners and landlords could use indoor air quality control
information to solve existing problems in residences.
Chamber studies
Initial health hazard comparisons of selected building materials, furnish-
ings, and consumer products will produce health assessments and source
characterizations that will provide an indication of the relative rankings of
indoor materials. Environmental test chambers provide a convenient means of
evaluating a variety of materials under controlled conditions. Available
sampling and analysis tools (sample adsorption and concentration followed by
gas chromatography) can provide information on organic species at low levels.
In addition, vapor phase bioassays can be performed on test chamber emissions.
Environmental test chamber research is needed to determine potential
exposures to organic mixtures emitted from selected materials. This research
August 1989 25
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should include developing emission rate data; predicting indoor concentrations
expected in buildings; conducting interlaboratory comparisons of small chamber
studies used by U.S., European, and Canadian investigators; and evaluating and
developing monitoring methods applicable to organic species and concentrations
occurring in chambers and expected in buildings. In addition, research is
needed to study interactions between pollutants and source and sink effects.
Research outputs needed include emission testing procedures, monitoring
methods, emission factors, and emission source models.
Exposure chamber studies
Exposure chamber studies provide opportunities to determine the impact of
indoor air pollutants on humans, animals, and other biological organisms. In
order to identify the hazards associated with exposure, the constituents of the
exposure must be determined and simple screening tests conducted to indicate
biological activity of the constituents at relevant concentrations. The focus
of the health effects testing should initially be on neurotoxicity and
genotoxicity.
Research will include genotoxicity studies, including short term vapor
phase bioassays, chemical analysis of active mixtures, and testing of reconsti-
tuted mixtures determined to have biological activity based on previous
studies. Included should be the conduct of controlled human exposure to
relevant volatile organic compounds and mixtures to determine the replicability
of previously reported psychological disturbances and the potential role of
trigeminal nerve activity in producing discomfort and dysfunction in sick
building syndrome. In addition, research is needed which will expose animals,
via inhalation, to relevant simple and complex VOC mixtures to screen for lung
irritancy and neurotoxicity.
Test home studies
Health assessments, source characterizations, and organic measurement
development will provide relative rankings of indoor materials in terms of
emissions and biological activity. Test-house evaluations allow the investiga-
tion of specific sources of indoor air pollutants without the confounding
influence of multiple (and often unknown) sources found in occupied buildings.
Test-house evaluations are necessary to provide "scale-up" and validation of
test chamber results.
Materials which indicate high relative health risk from the chamber
testing studies will be placed in the test-house. Organic monitoring will be
conducted concurrently and measurement methods validated. Emission factors
will be calculated and compared to those developed in the small chambers.
Source emission models will be calibrated and verified. Research applicable to
assessing health effects (e.g., bioassays) will also be conducted.
Characterization and dose-response
Characterization and dose-response of health hazards produced by emissions
from selected building materials and consumer products will accomplish several
objectives: aid in understanding the relationship between exposure to
emissions from indoor materials and internal dose; help determine the spectrum
August 1989 26
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of biological activity produced by these pollutants; and establish the
relationship between dose and the magnitude and nature of the biological
effect.
The potential bioactivlty of constituents of emissions from building
materials and consumer products to the indoor environment will be identified.
Once specific constituents and mixtures of VOCs are shown to have biological
activity, the risk assessment process demands knowledge of the nature of the
adverse effect as well as its dose dependence, so that extrapolation from high
to low dose and from animal to man may be accomplished.
Using data obtained from the hazard identification and screening studies,
dosimetry studies will be performed, including model development, studies of
respiratory tract removal of VOCs, and genotoxicity. Animal toxicology studies
will include whole animal studies of carcinogenesis and neurotoxicity, and
evaluation of pulmonary, developmental, and immunological consequences of
inhalation exposure to relevant simple and complex VOC mixtures. Controlled
human exposures will be used to evaluate potential neurobehavioral dysfunction
produced by constituents and mixtures of constituents identified and relevant
from hazard identification/screening studies.
Sink effect studies
The "sink effect" of building materials and furnishings on indoor organic
concentrations needs to be examined. Data are available on sink rates for N02
from combustion sources, and the goal of this research is to extend the limited
data available on the adsorptive capacity of building materials and furnishings
for organic compounds in indoor environments. An understanding of the adsorp-
tion (and subsequent re-emission) of indoor organic vapors is required because
organic sinks have the potential to reduce maximum indoor concentrations, or
they can act as sources which re-emit the compound.
A three stage research effort is proposed. The first stage will employ
small environmental test chambers to evaluate a variety of potential organic
sinks (e.g., gypsum wallboard, acoustical ceiling tiles, and carpets). The
potential sink effect of each material will be determined as a function of
chamber conditions (e.g., temperature, relative humidity, and air exchange
rate) for a variety of common indoor organic vapors. The role of building
materials as sinks for SOx, NOx, and particles will also be studied. The
second stage will involve validation of the test data in the test house, and
the third stage will be the initiation of field evaluations.
Material and product substitution
Evaluation of indoor air quality control via material or product modifica-
tion or substitution will determine the health risk effects associated with
these changes. Material'and product selection provides builders and occupants
the opportunity to control the indoor environment. Avoidance of materials and
products known or suspected to cause adverse health effects relies on knowledge
of the relative risks.
Initial emphasis will be given to materials determined to potentially pose
relatively high health risks. Studies will be conducted to determine the
reduction in risk caused by material substitution or modification. For
August 1989 27
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example, changing from urea formaldehyde pressed wood products to those using
phenol formaldehyde will reduce formaldehyde emissions. Well defined screening
tests can be developed to define the potential toxicity of proposed replacement
materials. Initial evaluations will be conducted in chambers, with follow-up
studies in the test house. The health effects work will be supported by source
characterization and monitoring.
Field studies
Field studies of indoor air pollutant concentrations, sources, and health
effects in residential and commercial buildings will be conducted to validate
and extend research findings. Field studies are a means by which to validate
and verify data, methods, and models developed under controlled conditions
(e.g., in environmental chambers and test houses). Such studies provide a
means for combining the health effects, monitoring, and source characterization
techniques into integrated evaluation protocols applicable to the investigation
of a variety of indoor air quality problems.
A five stage field study approach is proposed. This project will
integrate the indoor air quality research programs for all indoor pollutant
source categories. The first stage will be the identification of target
populations of human subjects (including responders and nonresponders to the
sick building syndrome), development of methods required to study specific
subsets of this population (e.g., children), and evaluation of the health
status (e.g., neurobehavioral function, trigeminal sensitivity) of partici-
pants. The second stage will involve a small sample of buildings (3-6) and
will refine and test the evaluation capabilities of the laboratories involved.
The third stage will be conducted on a larger sample (~10 buildings) and will
validate the methods and models developed by the indoor air research teams.
The fourth stage will include complaint buildings, including residences, and
will develop and test diagnostic and control procedures. Finally, the fifth
stage will be an evaluation of indoor air quality control techniques and
strategies.
3. Activity Sources
Normal day-to-day activities involve the use of a broad range of consumer
products, devices, and tools which can result in emissions of air pollutants.
Outdoors, with the possible exception of occupational activities, such expo-
sures are generally believed to be of only limited health consequence, largely
because of the diluting effect of the ambient air. Indoors, however, the
health implications may be more consequential, depending on the exposure
received in a given microenvironment. Even if indoor air pollutant concentra-
tions are low, they may make a substantial contribution to time-weighted
exposures due to the large amount of time spent indoors. If indoor personal
exposures are not taken into consideration in epidemiologic investigations,
spurious conclusions may be reached.
This section identifies a limited number of personal activities for
research. The object of the research is to identify exposures of concern to
the public and evaluate mitigation efforts.
August 1989 28
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Maintenance, work, and leisure activities
Within this grouping are the following sources:
Maintenance Activities: cleansers, waxes, polishes, paints,
vacuuming, room fresheners.
Work and Leisure Activities: glues, office machines, inks,
hobby materials, aerosol products, cleaning solvents.
Available data on organic compounds emitted from these sources are limited
to compound classes from solvent based materials and specific compounds and
product composition for a few specific products. Data on non-occupational
exposure to particles from activities which generate aerosols (e.g., spray
paints and waxes) or reentrained dust are nearly non-existent. Known informa-
tion on emission factors is limited to a few materials (e.g., emissions from
some waxes, paints and finishes). Limited data also exists for mass emissions
from aerosol products and anecdotal information on office machine emissions.
Information is required on the wide variety of indoor air pollutants
emitted from these products and materials, especially those associated with
maintenance, work, and leisure activities. Data are needed on material
composition, compound classes emitted, and organic emissions. Particulate
data, including particle size distribution, are needed for vacuum cleaning and
aerosol products. Information is required to determine the impact of tempera-
ture, humidity, air exchange, source characteristics (e.g., composition,
compound vapor pressure, reactivity), product use, and product age on emission
factors. Also, data are needed on: (a) vacuum cleaner characteristics and
their relationship to particulate emission rates, (b) the effect of can
pressure, percent product remaining in can, and application time on emissions
from aerosol spray products, and (c) the effect of office machine operating
parameters on emission rates.
Pesticides—home use
Significant exposures can occur from homeowner application of pesticides.
Sources include sprays, powders, moth cakes, and pest strips. The EPA Non-
Occupational Pesticide Exposure Study (NOPES) is gathering information in this
area.
Chemical pesticides have a wide range of toxicities and potencies, and
some, at sufficient exposure levels, can cause neurotoxicity, teratogenicity,
liver effects, cancer, and other serious effects. Because of existing regula-
tions (Federal Insecticide, Fungicide, and Rodenticide Act) there is some
health data on all pesticides. The information is especially inadequate,
however, on the distribution of indoor personal exposures to different
chemicals. Whenever the data base is found to be inadequate, EPA will require
the necessary data pursuant to its authority under the Federal Insecticide,
Fungicide, and Rodenticide Act.
Information is needed on the composition of pesticide emissions as well as
data on emission factors for pesticides in various forms (e.g., solid, spray,
powder). For determining emission factors, information is required on the
August 1989 29
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impact of temperature, humidity, air exchange, product use, and product age,
source characteristics (e.g., composition, compound vapor pressure, reactivity)
that affect emission factors, and the effect of can pressure, percent product
remaining in can, and application time.
Transportation
Personal exposures to organics and particles occur during the use of
private and public transportation (ground and air). Limited data on compounds
emitted are available on automobile interior emissions and commercial airliner
interiors.
Information is needed on material composition and on the compounds emitted
from interior materials (e.g., plastics, carpeting, fabrics, adhesives). Data
are required on emission factors for total organics and individual compounds.
Information is also needed on source characteristics (e.g., composition,
compound vapor pressure, reactivity) that affect emission factors, the impact
of temperature, humidity, air exchange, vehicle use, and vehicle age on
emission factors, and the effect of "sinks" on emission rates.
Non-ionizing radiation: extremely low frequency electric and magnetic fields
The high voltages and currents associated with electric power generation
result in electric and magnetic fields (typically at 60 Hz) in or near dwell-
ings, offices, and factories. In addition, the use of appliances with electric
motors or electric heating elements and the use of electric light bulbs produce
60 Hz fields. Many of these sources also generate electromagnetic fields at
other frequencies. Although data on indoor exposure characteristics are
sparse, exposure does occur, sometimes for long periods of time (i.e., children
in front of a TV set, people sleeping under an electric blanket or on a heated
waterbed).
Exposures to electromagnetic fields from the use of electric power have
been associated with numerous effects, most notably, carcinogenesis, reproduc-
tive effects, and nervous system effects. The epidemiological data base on
cancer is based on exposure to power distribution lines, which are located
outside virtually every house in the United States. Most of the effects
observed have been in laboratory studies which utilized exposure
characteristics very different from indoor exposures. In those few laboratory
studies that have employed indoor exposure levels, unusual biological
perturbations (e.g., impaired immune defense systems) were observed due to the
exposures. The limited epidemiological work on home appliances (use of
electric blankets and electrically heated water beds) suggests increased
spontaneous abortions for mothers exposed during the first trimester, a
lengthening of gestation, and a reduction in birthweight. Much additional
health effects information is available, but its extrapolation to the indoor
environment is qualitative, at best, until more is known about indoor exposure
characteristics and factors influencing the dose-response.
The literature on the health effects of electromagnetic fields, especially
60 Hz fields, indicates several areas of major concern, namely, cancer, repro-
ductive effects, and effects on the central nervous system. To aid in
extrapolation of the existing (and future) data to the population in general,
August 1989 30
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indoor exposures must be better characterized and validation and dose-response
studies are needed. Furthermore, to devise and conduct appropriate
experimental studies of the biological effects of electromagnetic pollution
inside man-made environments, the present electromagnetic environments must be
characterized and reconstructed inside the laboratory. Knowledge of these
parameters will enable a strategy to be developed to alleviate biological
hazards in the short-term, and possibly to eliminate them in the long-term.
Primary research needs include the validation of the potentially detrimental
biological changes caused by exposure to electric and magnetic fields
associated with electric power distribution and utilization, and the
investigation of the mechanisms of action of these effects. The focus of the
validation studies will be the establishment of dose-re<-ponse relationships. A
key element of the mechanistic studies will be the definition of the critical
electromagnetic parameters that are associated with the field-induced health
effects. The information obtained from these studies will used to design
epidemiclogical studies that explicitly focus on the radiobiological parameters
that the laboratory investigations have shown to be critical factors in
inducing biological effects.
4. Ambient Sources
The intrusion of environmental pollutants indoors has received increasing
attention since the late 1970s. While considerable research has been devoted
to understanding and predicting the movement, persistence, and degradation of
pollutants in the ambient environment, little information exists on the entry
of these substances into our homes, offices, and schools. Several studies have
been undertaken to assess the exposures indoors to the more common criteria
pollutants and, to a limited degree, to volatile organic compounds. More
recently, limited research has begun on indoor air exposures to pesticides.
Pesticides are introduced into the indoor environment through their normal
application, both indoors and out. The persistency of pesticides may lead to
buildups in the indoor environment with measurable amounts being found in the
air, on dust particles, on the walls, and on particles in the room for as long
as 35 days after the initial application of some types of pesticides. The
termiticide chlordane has been detected in the air of some treated homes
14 years after application. Organic vapors may enter the indoor environment
via infiltration from the soil and compounds contained in contaminated ground-
water may volatilize and enter structures via the same pathways as discussed
above for radon and pesticides. Also, seepage of groundwater or leachate from
land fills can enter substructures and organics contained in such seepage can
vaporize once indoors.
Outdoor Air
Pollutants in indoor air that originate from outdoor sources include air
quality criteria pollutants, hazardous pollutants, automobile exjiaust, and wood
smoke. Some viable and nonviable biological contaminants, such as certa-in
bacteria, molds, and pollens can also enter indoor spaces and may grow and
multiply indoors. Information available on penetration of these pollutants
into indoor environments is very limited. Little is known about the prevalence
of outdoor source types that affect indoor air quality. Some information is
known about the effects of infiltration (both above and below grade), relative
humidity, and temperature on indoor pollutant concentrations.
August 1989 31
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Information is required on the penetration of particles to determine the
contribution to exposures indoors. The effect of outdoor concentration on
indoor concentration needs to be determined as does the diagnosis of points of
entry and analysis of the factors that affect the amount of entry into
buildings.
Pollutants known to enter residences from soil are radon, pesticides,
heavy metals such as lead, toxic substances from waste sites, and some biologi-
cal contaminants. Because it has become common practice to treat the soil
beneath new construction with a termiticide, exposure is thought to be increas-
ing for pesticides. Wet areas and areas with high humidity are a prime factor
for increased mold growth.
Additional information which may be needed includes:
Identification and characterization of pesticides.
Development of measurement methods for detecting pesticides that
could enter homes from substructure soil.
A better understanding of the effects of vapor pressure, soil
composition, and soil porosity on pesticides entry rates in
individual homes. Development of pesticide emission factors and
source models. Investigation of effect of ventilation rates on
pesticide emission rates from soil.
Information on pesticide application practices and indoor
residuals from such use.
Characterization of the magnitude of the lead exposure problem
for residences where lead-based paint fragments have entered the
soil near the foundation.
Water
Domestic water supplies can be a source for releasing pollutants into the
indoor environment. Sources for organic compounds may include showers, dish-
washers, and clothes washers and their associated products. In addition,
metals, radon, and waterborne bacteria such as Legione11 a can also be released
from domestic water supplies into the indoor environment. This can occur from
vaporization at the tap or by using a home humidifier. Preliminary research
indicates that some humidifiers can release dissolved minerals and metals into
the air in the form of particles of submicron size. The most significant
releases by vaporization at the tap occur from showers. Temperature, surface
area exposed (degree of agitation, droplet size), and relative concentrations
in water and air affect the rate of pollutant release from domestic water. If
a primary source of radon is from well water, mitigation techniques are known,
but further research is needed to evaluate the long-term effectiveness of these
techniques.
August 1989 32
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Information is needed on the classes of compounds and specific organics
emitted. Information is also needed on emission factors (mg/kg) for total and
individual organics. For showers, data are needed to determine the effect of
organic content, temperature, humidity, and shower spray characteristics on
emission rates. Additionally, for laundry machines and dishwashers, informa-
tion is required on the effect of organic composition, vapor pressure, and
reactivity on emission rates (including the influence of detergents, bleaches
and other additives). Information is needed to determine emission factors,
ventilation parameters for various building types (including the effect of
bathroom and kitchen ventilation fans), water use patterns, and use of
laundry/dishwashing detergent and additives.
Information is also needed to better characterize the emission process for
dissolved constituents, especially heavy metals such as lead, when using
humidifiers.
5. Sources of Biological Contaminants
Microorganisms and other antigenic biological material are of particular
concern in indoor environments, because various sources and conditions found
indoors provide the opportunity for organisms to grow and for microbes and
other materials to become airborne. Indoor exposures to these organisms (e.g.,
molds, spores, bacteria, and viruses) and animal excreta are associated with a
broad spectrum of health effects, ranging from life-threatening diseases (e.g.,
Legionnaires disease) to nonspecific health complaints (e.g., sick building
syndrome). Prominent among known indoor sources of biological contaminants are
water reservoirs, including humidifiers, air conditioning systems, and shower
heads. HVAC systems, carpets, upholstery, and dander from pets are other
sources.
Despite growing public health concerns about this biological contamination
indoors, little is known about the sources, human exposures, and health
effects. Most research to date has been conducted on acute episodes at
individual locations. There is a need to continue research devoted to
establishing "normal baseline" concentrations for the more important biological
contaminants, and to develop standardized monitoring and measurement
techniques. Due to a lack of such techniques, relatively little has been done
to document the level or extent of exposures to these contaminants. Very
little information exists relating individual biological contaminants to
particular health effects. Even where such effects have been identified (e.g.,
Legione11 a and allergic reactions), dose-response relationships have not been
established and the potential range of adverse health effects is unknown. For
example, some mycotoxins are carcinogenic, but it is not known whether indoor
levels pose a significant carcinogenic risk. There is reason to hypothesize
that biological contaminants can have significant involvement in sick building
syndrome, but this is a relatively unexplored issue. Sensitive subpopulations
have not been fully identified or characterized.
The development of standardized monitoring and measurement techniques is
necessary to provide the foundation for subsequent research on biological
contaminants. The techniques must take into account differences in indoor
spaces such as for rooms as opposed to whole buildings, residences as opposed
to office buildings.
August 1989 33
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Research has been initiated to characterize baseline levels of biological
contamination. The continued development -of baseline concentrations will
involve monitoring of indoor background levels and major classes of biological
contaminants. It will include a survey of levels of mycoflora and other
biological types found in varying indoor environments in order to establish a
baseline for study of concentrations of concern to human health. The influence
of season, geography, building type, mechanical systems, and furnishings on
background levels of fungi, bacteria, and other biological contaminants will be
studied, and indoor/outdoor ratios will be established. Identification of
exposure levels associated with particular infections, diseases, or allergic
reactions is also needed.
Humidity is known to be a prime factor affecting the growth of various
bacteria, molds, and other contaminants (e.g., dust mites) on common indoor
surfaces (e.g., curtains, upholstery, carpeting, leather, wood, and fiber-
glass). Research should identify optimum humidity conditions for growth and
control of biological contaminants, and assess the relationship between
humidity levels and the onset of or susceptibility to infectious diseases and
allergies.
Exposures to biological contaminants from systems which condition air are
believed to be both widespread and frequently intensive; however, little is
known about the significance to health of these exposures. Air conditioning
systems (e..g. , cooling coils, water reservoirs, and ventilation ducts) are
known to be prime breeding grounds for a range of biological contaminants,
including molds and infectious agents. Once established, these contaminants
are easily distributed throughout indoor environments by the forced ventilation
components of these systems. A need exists to identify the nature and extent
of biological contaminants commonly found in these systems.
Research is necessary to identify sources of biological toxins in the
indoor environment, quantify exposures, and relate exposures to the occurrence
of human health effects. Soil bacteria and other biological contaminants may
also result in indoor pollutant exposures. Preliminary research has already
been undertaken to assess the growth of Legionella in air conditioning systems
and humidifiers. Additional research should also investigate approaches for
controlling these bacteria and allergenic materials in known and newly
identified sources.
A survey of geographic patterns of infection and allergy is also neces-
sary, although this research would be both complex and difficult. This project
will use physician reports to identify patterns of infection and allergy,
followed by on-site sampling to identify causative indoor biological organisms.
The work will eventually be useful in diagnosing buildings.
August 1989 34
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D. CONTROL TECHNIQUES
Research is needed on the effectiveness, reliability, energy implications,
and cost of many existing techniques of controlling indoor air quality so that
the best options can be selected. In addition, existing control techniques are
not fully satisfactory for many pollutants. Thus, research that will lead to
entirely new or improved control techniques is needed.
1. Source-Specific Controls
Presently, there a few satisfactory options for reducing pollutant concen-
trations in existing buildings once sources are in place. Removal of sources
is often prohibitively expensive. One alternative that seems to be promising
is the application of coatings on building materials. Researchers have demon-
strated that vinyl linoleum flooring or polyethylene vapor barriers over
particle board underlayment may significantly reduce formaldehyde emissions.
Additional research is needed on the effectiveness of such coatings, especially
for VOCs other than formaldehyde, and other methods of reducing emission rates
in existing buildings.
Research needed includes: a) chamber studies to evaluate emission charac-
teristics of modified or coated materials, b) IAQ model studies to evaluate
source control strategies, including verifications, and c) field studies to
evaluate source control strategies used in occupied buildings. The research
would benefit by cooperative ventures with manufacturers of materials and
products in the areas of product modification and coatings. Cooperation with
builders and architects in the areas of changing use patterns and material/
product substitution would also be beneficial.
Environmental tobacco smoke
Smoking restrictions, public education, voluntary isolation of smokers
from nonsmokers, ventilation, and filtration will continue to be examined as
the primary methods of reducing exposure to ETS. These same measures are
appropriate for residential buildings. Research on "physical" tobacco smoke
control techniques (in contrast to regulatory measures) should include investi-
gations of: (a) methods of ventilation that reduce the spread of tobacco smoke
throughout buildings, (b) the impact of the existing filter systems in
commercial buildings on indoor tobacco smoke concentrations, and (c) the
potential of air-cleaning equipment to remove the most important gaseous
components and odors of tobacco smoke. The research for these topics is
covered under the air cleaner and ventilation control sections of this report.
Combustion products emitted by appliances
Combustion appliances can emit nitrogen oxides, sulfur oxides, carbon
monoxide, particulate matter, and organic compounds. Although product substi-
tutions are often an effective method of control, such substitution may be
limited by economic and other factors. It is known, for example, that range
hoods and electronic ignition systems may be effective in reducing pollutant
emissions from gas ranges. While it is also known that effective maintenance
is important in reducing emissions, the elements of such a maintenance program
need to be identified.
August 1989 35
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The effect of design and operation modifications on pollutant emissions
must be determined for all combustion appliances. Performance standards need
to be developed for these appliances. Research on effective, low-cost air
cleaning elements for existing range hoods is needed, as well as research on
the economics of modifying sources to reduce emissions. However, as a general
practice, combustion appliances should be vented to the outdoors.
Asbestos
Techniques of asbestos removal are well developed and routinely utilized
by the private sector. Research is needed that can lead to improved and less
costly methods of determining the need for asbestos removal in specific build-
ings. Such research should include investigations of the relationships between
asbestos sources and location, conditions of the building, and the potential
for release of asbestos fibers.
Microbiological agents
Microbiological agents are a major cause of poor indoor air quality. As
is discussed in previous sections, the information on microbiological agents is
limited. However, research should begin to study the methods of controlling
the indoor concentrations.
Research on environmental factors (temperature, humidity, presence of
other materials) that affect growth of microbiological agents supports develop-
ment of control techniques by defining regions of building operation that will
prevent or limit microbiological contamination. The above research will also
allow development of operation and maintenance procedures that can reduce or
eliminate risk from microbiological contaminants. Research on the use of
biocides is needed.
2. Ventilation Strategies
Some indoor air quality problems can be solved by increasing ventilation
rates and/or ventilation effectiveness. These increases may be applied locally
or to the entire building. The selection of an appropriate ventilation
strategy depends on the effectiveness and economics of various strategies, and
requires knowledge of the effect of the strategy on pollutant concentrations.
Ventilation research needs are discussed in the Building System Needs section.
One of the key unknown variables is the effects of ventilation on source
emission rates and pollutant sinks. Another important unknown is the effect of
local ventilation on overall building ventilation.
3. Air Cleaners
Ideally, adequate indoor air quality could be maintained by control of
pollutant source strengths together with ventilation. In real-life situations,
however, the indoor concentrations of one or a few pollutants may be elevated
and pollutant source control can be difficult and costly. Research is need to
develop effective and practical air-cleaning technologies.
August 1989 36
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Particles
Data on the overall mass collection efficiency of filters for dust are
available, but these data do not allow analysis of the effectiveness of air
filters for control of many of the particles found indoors. The evaluation of
the effectiveness of particulate air cleaners starts with the determination of
the efficiency of various cleaners as function of particle diameter. Then data
on the effects of circulation rates on effectiveness must be known. Evaluation
of the long-term effectiveness of air cleaners requires information on the
effects of collected dust, pollutant interactions, and organics on cleaner
effectiveness. Data on possible sink/re-emissions are also required. Data on
the effects of particulate air cleaners on biological pollutants are required.
The development of simple air cleaner evaluation procedures is required, and
models and small scale experiments should be verified with field studies.
Organics
Data on the performance of activated carbon on individual compounds
indicate that carbon is not generally useful for controlling organics at the
low concentrations found indoors. Rather, data on the performance and
economics of effective organic air cleaners are needed. The collection of
organics in indoor air is a complicated problem because in some cases the
pollutants may be a single compound or a complex mixture of numerous compounds.
Information is required on pollutant generation by air cleaners and the effects
of particles and building conditions (temperature, RH, etc.) on organic air
cleaner efficiency. The control of low concentration levels of organics will
probably require new technological developments.
Biologicals
Research on the effectiveness of air cleaners in removing microbiological
agents and on the growth of microbiological agents in air cleaners is needed
and is covered in the air cleaner research program.
Pesticides
The effectiveness of air cleaners for removing or destroying indoor
pesticides needs to be determined, as well as the usefulness of radon control
measures for simultaneously reducing chlordane or other termiticide vapors.
Evaluation of both passive and active control methods for pesticide vapor is
also needed.
August 1989 37
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E. BUILDING SYSTEM NEEDS
Indoor air pollution problems are caused by the complex interactions of
sources, sinks, and ventilation. Indoor air quality problems and solutions
must thus be approached from the building system standpoint, which takes all of
these interactions into account. The first step, however, is to determine the
performance of the various components of the building system. Once the
performance of the components is understood, it will be possible to define
their interactions.
The building system, especially the heating, ventilating and air condi-
tioning system (HVAC), plays a major role in determining indoor air quality.
In addition to conditioning the indoor air, the primary purpose of a building
HVAC system is to distribute ventilation air throughout the building and to
remove and dilute indoor pollution. However, an ineffective HVAC system
(improperly designed, constructed, operated, and/or maintained) can be not only
ineffective at controlling indoor pollutant levels, but can also be a signifi-
cant source of pollutants, especially biological contaminants and fine
particles.
Ventilation is therefore a key determinant of indoor air quality. Venti-
lation includes the flow of outdoor air into and out of the building and
inter-room air flows. In addition, the term ventilation effectiveness is used
to characterize the distribution of air within a room. A quantitative under-
standing of all these flows and how they affect pollutant levels is essential
to understanding indoor air quality.
Inadequate ventilation has been identified as a major contributing factor
to sick building syndrome, and since the causes of sick building syndrome are
as yet poorly defined, most mitigation procedures typically focus on the
general increase of air flow and ventilation. More information is needed about
the causes of SBS in order to identify specific mitigation procedures for
source control which could be coupled with ventilation to achieve the most
cost-effective prevention strategy.
Ventilation
In response to the need to conserve energy, considerable research has been
devoted to studying both ventilation and infiltration (the uncontrolled
introduction of outside air through the building shell) in buildings. This
research has developed techniques for measuring and modeling these flows in
both residential and large buildings. The results of this research are being
incorporated into the modeling efforts described earlier. Additional research
is needed to refine these techniques, e.g., the continued development of
multi-tracer gas systems for measuring interzonal flows and pulsed tracer gas
techniques for measuring ventilation rates.
In addition, research is needed to develop measurement techniques and
protocols for measuring ventilation that can be widely applied by non-
researchers. These techniques are needed to assist in both the diagnostic and
subsequent evaluation of complaint buildings. One such technique is the
measurement of carbon dioxide as a surrogate of acceptable ventilation and/or
indoor air quality. The validity of this and similar techniques requires
additional research.
August 1989 38
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Research is- also needed devoted to continuing laboratory measurements of
ventilation flows. This research provides a necessary link between modelled
air flows and those measured in the field. This research includes both scale
model studies of ventilation flows and laboratory mock-ups of novel ventilation
systems.
Finally, techniques and protocols are needed to measure ventilation
effectiveness under both laboratory and field conditions. These techniques
should quantify how much ventilation air is actually provided from central air
handling units to occupied building spaces, how well this air is distributed
within the breathing zone of the occupants, and how effective the air flow is
for removing and diluting indoor pollutant levels. This research will greatly
assist in evaluating the effects of supply diffuser and return grille loca-
tions, open windows and doors, appliances, local fans, and human activities on
ventilation performance.
Field measurements
The existing data on field measurements of ventilation rates and ventila-
tion effectiveness in buildings is very limited. Because the impact of
ventilation on indoor air quality is so important, research devoted to
performing indoor air quality studies in buildings must include measurements of
both ventilation rates and effectiveness. These measurements are needed to
properly evaluate appropriate mitigation approaches (if needed), validate and
compare different measurement techniques for assessing ventilation performance,
and expand our data base of such measurements.
The total building system
The total building system extends beyond just the building's HVAC system.
It also includes all of the (other) sources of and sinks for indoor pollutants
within the building including people, furnishings, building materials, and the
soil system influenced by the operation and/or construction of the building.
Research is needed to assess the combined effects of the factors which deter-
mine indoor air quality, emphasizing both the relative importance of specific
pollutant sources and the capabilities of the HVAC system to handle them.
This research is particularly applicable to new building design. It would
address how to design buildings which provide acceptable indoor air quality,
rather than how to mitigate complaint buildings. Multiple buildings should be
studied from the selection of materials and HVAC systems at the design stage
through construction to ongoing operation and maintenance.
August 1989 39
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F. CROSSCUTTING RESEARCH
Indoor Air Quality and Productivity
Research is needed to quantify the impact of maintaining acceptable indoor
air quality on worker productivity. For example, it has been estimated that if
reducing ventilation rates by 25% reduces the productivity of an employee by
5 minutes a day, then "bottom line" costs will be increased. Research is
needed to quantify the relationship between worker productivity and indoor air
quality parameters such as pollutant concentrations and ventilation rates.
Although it will be difficult to distinguish the indoor air quality component
on productivity, such a study would provide a quantification of the economic
benefit associated with maintaining acceptable indoor air quality.
Epidemiology and Demographics Regarding the Effects Due to Chemical and
Physical Agents
Careful epidemiologies! and medical studies need to be done in buildings
to determine the prevalence and incidence of symptoms and other medical
conditions in relationship to chemical and physical agents (and as needed to
evaluate effects of ergonomic and stress problems). Even though NIOSH has
evaluated hundreds of indoor air quality problems, there is still a lack of
information on the real differences between problem buildings and non-problem
buildings. Research is needed to develop a protocol that would first be used
in non-problem buildings so that comparisons of the various study parameters
might lead to a better understanding of important differences with respect to
worker complaints (frequency and type), building type, ventilation, chemical,
phyical, biological, environmental, and ergonomic and psychosocial parameters.
The baseline data would then be used to evaluate indoor air quality problems in
a more comprehensive manner. This research would include studying 8-10 problem
office buildings. Study parameters would include a general characterization of
the building (e.g., design, employee activities, smoking policy), employee
questionnaires, an assessment of building ventilation, and industrial hygiene
sampling.
Ergonomic and Psychosocial Research
In coordination with the evaluation of the problems associated with
physical and chemical agents, the contribution of psychosocial and ergonomic
stress factors associated with indoor air quality problems needs to be studied.
Ergonomic factors to be examined include the physical design of workstations
(e.g., worktables, chairs, and tools), aspects of the ambient environment,
interior design of the workplace (e.g., noise and lighting conditions), and
task characteristics (e.g., repetitious tasks, constrained or awkward
postures). Relevant psychosocial factors would include task and organizational
factors such as task complexity, skill utilization, control, social support,
workload demands, and role demands. These factors could be objectively
measured or assessed via survey techniques, and their effects determined by
multivariate statistical methods. Since many of these variables are readily
manipulated, opportunities exist for controlled field (workplace) experiments,
and for interventions to test control measures. This effort would be the
refinement of existing survey instruments so they can be readily applied in the
context of indoor air quality studies.
August 1989 40
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G. TECHNOLOGY TRANSFER
The ultimate goal of the Federal indoor air research program is the
dissemination of information to the public, useful for both characterizing and
mitigating the potential risks associated with indoor air pollution. There-
fore, technology transfer is an essential part of the indoor air research
program.
The Federal government, State and local government agencies, and the
private sector are all responsible for effectively sharing information both
with each other and the general public. This transfer of information must
occur in both directions — both from the agencies conducting research to
potential users and from users to the research community to establish meaning-
ful research needs.
Mechanisms for transferring the results of indoor air research include
publishing public information materials, co-sponsoring technical conferences
and workshops, and enhancing communication among Federal and State agencies and
the private sector. One very successful technology transfer mechanism has been
the performance of health hazard evaluations in office buildings in response to
reported health complaints or illnesses. Over 500 evaluations have been
completed to date. In addition, an indoor air quality clearinghouse is also
needed that serves the different information needs of researchers, health
officials, and consumers.
For example, State and local governments are approached first by the
public for help in assessing and solving immediate indoor air quality problems.
Information to support the needs of state and local officials is important to
the indoor air pollution research plan.
Technology transfer is a high priority for state and local officials, who
stress the need for federally developed materials intended for the general
public, such as the radon citizen guides. However, care should be taken in
disseminating preliminary research results, so as not to alarm or desensitize
the public. Public information should first and foremost characterize the risk
presented by indoor air pollution and should present the available mitigation
methods. Information materials should be developed with consideration of the
regional differences that can affect the appropriateness of the information
contained.
State agencies have proposed that EPA designate one official in every
Regional Office to serve as an indoor air expert to assist in technology
transfer. The regional EPA official would serve as a contact for information
regarding Federal indoor air research activities. Specifically, this person
should work actively with state personnel and gain intimate knowledge of their
indoor air needs and activities. The EPA Regional Offices should also pursue
personnel exchanges between state and EPA programs.
Increased participation in the activities of technical and professional
organizations (e.g., the American Society of Heating, Refrigerating, and
Air-Conditioning Engineers, the Air Pollution Control Association, the American
Industrial Hygiene Association, and the American Society of Testing and
Materials) can facilitate the transfer of information among Federal agencies,
states, and the private sector. These interactions can promote cooperative
August 1989 41
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research and minimize unnecessary duplication of effort. In fact, more joint
activities among these organizations, especially conferences and workshops, are
needed to exchange indoor quality information of multidisciplinary interest.
In addition, consumer groups such as the Consumer Federation of America
have recommended the establishment of an indoor air quality clearinghouse.
Such a clearinghouse could serve to compile and distribute information ranging
from technical publications to informational pamphlets generated by both the
public and private sectors.
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III. ADDITIONAL READING
LEGISLATION
Statutes-at-Large. (1972) Consumer Products Safety Act of 1972, PL 92-573,
October 27, 1972. Stat. 86: 1207.
U. S. Code. (1986) Radon Gas and Indoor Air Quality Research. U. S. C. 42: sec.
7401 et seq.
U. S. Code as Amended. (1987) Federal Insecticide, Fungicide, and Rodenticide
Act. U. S. C. A. 7: sec. 136 et seq.
U. S. Code as Amended. (1987) Toxic Substances Control Act. U. S. C. A. 15:
sec. 2601 et seq.
U. S. Code as Amended. (1987) Toxic Substances Control Act. Title II. Asbestos
Hazardous Emergency Response. U. S. C. A. 15: sec. 2641 et seq.
U. S. House of Representatives. (1987) Indoor Radon Abatement Act of 1988.
Washington, DC: U. S. Congress; bill no. HR 2837.
REPORTS
Craig, A. B. (1988) Status of EPA (Environmental Protection Agency) radon
mitigation demonstration project. Research Triangle Park, NC: U. S.
Environmental Protection Agency, Air and Energy Engineering Research
Laboratory; EPA report no. EPA/600/D-88/037. Available from: NTIS,
Springfield, VA; PB88-171178/REB.
Interagency Committee on Indoor Air Quality. (1985) Comprehensive indoor air
quality research strategy, January 1, 1985. Washington, DC: U. S. Environ-
mental Protection Agency, Interagency Committee on Indoor Air Quality; EPA
report no. EPA/600/9-85/021. Available from: NTIS, Springfield, VA;
PB85-246692/REB.
Interagency Committee on Indoor Air Quality. (1986) Indoor air quality research
plan [Report to the Honorable Edward P. Boland, Chairman of the Sub-
committe on HUD-Independent Agencies, U. S. House of Representatives].
Washington, DC: U. S. Environmental Protection Agency.
National Research Council. (1986) Environmental tobacco smoke: measuring
exposures and assessing health effects. Washington, DC: National Academy
Press.
Surgeon General of the- United States. (1986) The health consequences of
involuntary smoking: a report of the Surgeon General. Rockville, MD: U. S.
Department of Human Services, Office on Smoking and Health.
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U. S. Environmental Protection Agency. (1987) EPA (Environmental Protection
Agency) indoor air quality implementation plan. A report to Congress under
Title IV of the Superfund Amendments and Reauthorization Act of 1986:
radon gas and indoor air quality research. Washington, DC: Office of Air
and Radiation; EPA report no. EPA/600/8-87/031. Available from: NTIS,
Springfield, VA; PB87-210720/REB.
August 1989 44
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