Program Needs for 

Indoor Environments Research (PNIER)

March 2005

www.epa.gov/iaq/pdfs/pnier.pdf
U.S. EPA, 402-B-05-001, March 2005
U.S. EPA, 402-B-05-001, March 2005 1

U.S. Environmental Protection Agency

Program Needs for Indoor Environments Research (PNIER)

 INTRODUCTION

Overview:

All across our nation, people live, work, and learn in indoor environments. On average, people

spend approximately 90% of their time indoors, where many pollutant levels are often two to five

times higher than outdoors. The EPA and its Science Advisory Board have ranked indoor air

pollution among the top five environmental risks to public health (U.S. EPA, 1987;

U.S. EPA, 1990).

The Indoor Environments Division (IED), located within the Office of Radiation and Indoor Air

(ORIA) under the Office of Air and Radiation (OAR), is the lead U.S. EPA program office for

issues relating to indoor environmental quality. The Indoor Environments Division focuses on

several priority areas including: indoor air toxics, asthma, radon, schools, and environmental

tobacco smoke. Additionally, there are several other offices within the EPA that have significant

responsibilities related to the indoor environment within their programs. These offices include,

but are not limited to, EPA Regional Offices, the Office of Research and Development (ORD),

the Office of Children’s Health Protection, the Office of Pollution Prevention and Toxic

Substances, the Office of Solid Waste and Emergency Response, and the ORIA laboratories.

This document, Program Needs for Indoor Environments Research (PNIER), is a strategic

document outlining EPA’s research needs for the indoor environment. The PNIER concept was

initiated within the Indoor Environments Division, and the document developed into its present

form through strong collaboration with other EPA offices. PNIER is considered a ‘living

document’ that can evolve to reflect the changing needs of EPA program offices and researchers

through periodic updates and revisions.

PNIER is intended to be a document that captures the indoor environments research needs for all

EPA offices with program responsibilities related to indoor environmental quality. It is

envisioned that PNIER will be a valuable document that can serve several purposes, including: 

• articulating EPA’s indoor environments research needs, for both internal and external uses;

• identifying where knowledge gaps exist;

• helping to establish a more well-defined presence for an indoor environments research

program at EPA;

• facilitating collaboration between EPA program offices and research offices when developing

research agendas and awarding research grants;

• fulfilling EPA’s Healthy Buildings, Healthy People (HBHP) initiative, which calls for the

development of a high-level, cross-Agency indoor environments research strategy. PNIER

could serve as EPA’s foundation towards this larger cross-agency research strategy, and could

influence research performed by other agencies and organizations (U.S. EPA, 2001).
2 U.S. EPA, 402-B-05-001, March 2005

PNIER is limited to the EPA’s indoor environments research needs, and is not intended to be a

‘global’ document for all possible indoor environments research. While PNIER is intended to

describe EPA’s indoor environments research needs, it is not envisioned that all research

contained within PNIER be performed directly by EPA’s research community. In some cases, it

may be appropriate for the research to be performed by other government agencies, private

industry, non-profit organizations, or other outside parties. It is also important to note that

while PNIER describes research needs, it does not attempt to prioritize the research needs

or catalog any ongoing research efforts that may support PNIER. 

PNIER Development History:

The PNIER development process included close coordination with a wide range of EPA offices

and staff. The following PNIER development and review sequence was performed:

• The initial PNIER concept was presented, with requests for input and comment, to EPA’s

Indoor Environments Division staff and EPA Regional staff working on indoor air and

radon-related issues in a series of meetings held during the spring of 2001. The initial PNIER

concept was also presented to the EPA’s ORD staff, and staff from other EPA offices, at an

Indoor Environments Scientist-to-Scientist meeting in May 2001. 

• Members of the IED Scientific Analysis Team outlined and drafted preliminary sections for

the PNIER programmatic and technical areas shown in the content outline on page 4. Outlines

and preliminary drafts were discussed and revised by the IED Scientific Analysis Team during

regular meetings dedicated to PNIER (June 2001-February 2002).

• The IED Scientific Analysis Team conducted an internal team-based review of the initial

compiled draft of PNIER, and developed a revised draft (March 2002 - May 2002).

• PNIER was reviewed by the IED Division Director and IED staff. Comments were resolved,

resulting in a version of PNIER that was considered a suitable starting point for soliciting

input and comments from other EPA offices (June 2002 - November 2002).

• The initial PNIER draft developed by the Indoor Environments Division was distributed to the

following EPA organizations for review and comment in January 2003:

S Office of Research & Development (ORD)

S Office of Children’s Health Protection (OCHP)

S Office of Prevention, Pesticides and Toxic Substances (OPPTS)

S Office of Solid Waste and Emergency Response (OSWER)

S Office of Air and Radiation, Office of Air Quality Planning and Standards (OAR/OAQPS)

S Office of Air and Radiation, Office of Atmospheric Programs (OAR/OAP)

S Office of Air and Radiation, Office of Transportation Air Quality (OAR/OTAQ)

S EPA Regional Offices (Regional Program Managers for indoor environments)

S Radiation & Indoor Environments National Laboratory / Las Vegas (RIENL)

• Comments were received from reviewers between late January and late April 2003. IED staff

considered the review comments and developed a revised version of PNIER that was

redistributed to EPA reviewers (April-July 2003). 

• Indoor environments research needs, primarily within the context of PNIER, were discussed

during an Indoor Environments Scientist-to-Scientist meeting on September 3-4, 2003, that

included staff from several EPA offices. Follow-up actions planned from that meeting include
U.S. EPA, 402-B-05-001, March 2005 3

ORD developing an indoor environments ‘research framework’ for presentation to ORD’s

upper management, modifying the EPA’s multi-year research plans to incorporate indoor

environments research needs, and evaluating ORD’s capabilities and identifying research that

may be accomplished through organizations external to the EPA.

Indoor Environments Research Criteria:

The following criteria were established for assessing the suitability of research items to be

included in PNIER:

1. Research must be consistent with the EPA’s authorization under Title IV of the Superfund

Amendments and Reauthorization Act of 1986 (SARA), which gives the EPA broad

authority to conduct research on indoor air quality (IAQ) issues, develop and disseminate

information on IAQ, and coordinate IAQ efforts at the federal, State and local levels.

2. Research should be for indoor environmental health risks predominantly due to inhalation

exposure, and health risks predominantly associated with indoor sources, or which may be

managed by controlling indoor exposures. This also includes managing outdoor sources that

impact the indoor environment.

3. Research should focus on indoor environments that the general public frequently accesses

(e.g., residences, schools, offices, public buildings, vehicle passenger compartments, etc.). 

Research should not address specialized indoor environments with established regulations

(e.g., industrial work sites, hospitals, and other specialized occupational settings).

4. Research should address perceived high risk areas where there is a practical likelihood to

implement corrective actions. Research is expected to provide a reasonable return-oninvestment.

5. Research that motivates public action, industry development, and real-world implementation

of indoor environmental improvements should be included.

6. Research that builds on the existing knowledge base and that supports current EPA activities

and priorities for the indoor environment should be included.

7. Research should be accepted and endorsed by organizations outside the EPA

(peer acceptance of the research).

8. Research should focus on areas that are not currently addressed by mature programs

(e.g., asbestos, lead).

9. Research should be for efforts that could be initiated within the next five years, and

completed within the next ten years. Research may include efforts that are already underway

or represent an expansion of those efforts.

10. When research is intended to develop methods to mitigate indoor air problems, an analysis of

the efficacy of the methods should be done.
4 U.S. EPA, 402-B-05-001, March 2005

PNIER Content Outline: 

Indoor environmental quality is an extremely broad subject, and there are many possible options

for presenting research categories. The following content outline was developed as an attempt to

meld categories useful for organizing basic research with those that support EPA’s program

needs. Detailed indoor environments research needs for these outline topics are presented in the

following sections, starting on page 5.

A. POLLUTANTS, SOURCES AND HEALTH EFFECTS

A.1. Chemicals (Including Indoor Air Toxics)

A.2. Biological Contaminants

A.3. Sensitization, Allergy and Irritation Health Effects

A.4. Particulate Matter

B. HUMAN PERFORMANCE

C. IAQ MEASURES AND INDICES

C.1. Building IAQ Indices

C.2. Development of Public Health Measures for IAQ

D. BUILDING DESIGN AND OPERATION

D.1. Building Characterization and Intervention

D.2. Ventilation Systems

D.3. Radon Control

D.4. Building Design and Implementation

E. HOMELAND SECURITY

F. PRODUCT AND TECHNOLOGY VERIFICATION

References for Introduction:

U.S. Environmental Protection Agency (U.S. EPA). 1987. Unfinished Business: A Comparative

Assessment of Environmental Problems. Washington DC: U.S. Environmental Protection

Agency.

U.S. Environmental Protection Agency (U.S. EPA). 1990. Reducing Risk: Setting Priorities and

Strategies for Environmental Protection. Washington DC: U.S. Environmental Protection

Agency. EPA-SAB-EC-90-021.

U.S. Environmental Protection Agency (U.S. EPA). 2001. Healthy Buildings, Healthy People: 

A Vision for the 21st Century. Washington DC: U.S. Environmental Protection Agency. 

EPA 402-K-01-003. 
U.S. EPA, 402-B-05-001, March 2005 5

A. POLLUTANTS AND SOURCES

A.1. CHEMICALS (INCLUDING INDOOR AIR TOXICS)

Background Information:

In the early 1980's, the relatively high exposures and potential risks from toxic chemicals in the

indoor environment became recognized through the EPA Total Exposure Assessment

Methodology (TEAM) studies (Wallace, 1987). Since that time, the potential exposures and

risks from toxic chemicals in indoor air have been confirmed by a number of studies, both within

and outside EPA (U.S. EPA, 1998). However, with the exception of joint programs between

ORIA and OPPT in the late 1980's and early 1990's to address emissions from carpet products

and wall paint, little effort has been directed at research to evaluate and manage these exposures

and risks, in part because there have been no regulatory drivers that require EPA to do so.

Since the enactment of the Clean Air Act Amendments of 1990, work on reducing toxic

chemicals in ambient (outdoor) air from stationary emissions sources has focused mainly on

developing standards based on technology [i.e., maximum achievable control technology

(MACT) and generally available control technology (GACT) standards]. The Agency is now

required to address the “residual risk” remaining after promulgation of these standards and,

therefore, is moving into a “risk-based” assessment process which requires new and improved

assessment tools. In addition, the Agency’s mobile source program is required to study the need

for, and feasibility of, controlling emissions of toxic air pollutants associated with motor vehicles

and fuels, and to set technology-based standards to reduce exposures from these sources. While

the Agency is mandated to address toxic air pollutants from outdoor sources only, in some cases

indoor exposures to these substances may be greater than those from outdoors. Currently, the

Agency does not know enough about the relative exposures and risks resulting from indoor and

outdoor sources to fully understand the relative importance of these sources.

In the past few years, the outdoor and indoor air toxics programs have become much more

integrated and have started to address the close connections between indoor and outdoor

environments and each environment’s impact on the other. Although research is needed to

address indoor, stationary, and mobile sources of toxic air pollutants, in general, research has

focused on outdoor air toxics.

While some research on chemicals and mixtures is useful for determining risks from both indoor

and outdoor pollutants (e.g., dose-response assessments, time-activity studies), certain types of

unique research activities are needed to address indoor risks. For example, the methods used to

determine emissions characteristics, to model the flow of pollutants, to study the fate and

transport of pollutants, and to manage risks are substantially different for indoor and outdoor

environments. Therefore, in these areas, research directed at studying outdoor pollutants cannot

substitute for indoor air research. 

The long-term program goals for research on chemicals and their sources are to: (1) develop and

refine systems that can be used on an ongoing basis to prioritize and select those chemicals and

mixtures, in addition to radon and environmental tobacco smoke, that are of concern in indoor
6 U.S. EPA, 402-B-05-001, March 2005

environments, (2) further develop methods to determine how the selected pollutants and mixtures

of concern interact with the indoor environment, with each other, and with other chemicals

(e.g., ozone), (3) examine the determinants of exposure for, and the potential risks posed by, the

chemicals and mixtures of concern, and (4) develop methods and practices that can be used to

mitigate any substantial risks of the selected chemicals and mixtures.

Program Needs for Chemicals (Including Indoor Air Toxics) Research:

A.1.a. Determine chemicals and mixtures found in indoor environments.

A.1.a.1. Perform additional baseline analyses to determine the typical levels of

chemicals in indoor environments.

EPA recently completed the sampling portion of the Building Assessment,

Survey, and Evaluation (BASE) study to determine the typical concentration

distributions of a number of chemicals found in a representative sample of U.S.

office buildings and to correlate these pollutant levels with building parameters

and occupant activities and symptoms. However, similar studies have not been

completed in other types of buildings (e.g., homes, schools, day care facilities,

retail establishments, etc.) and the number and types of pollutants monitored in

the BASE study was not comprehensive (i.e., chemicals to be monitored were

selected based on past studies and ease of sampling and analysis). Studies such as

BASE need to be expanded to a larger set of building environments and a broader

spectrum of pollutants (see section D.1.a. for additional discussion). In addition,

the data (existing BASE data and future data collected) need to be analyzed to

assist in determining the potential sources of the chemicals indoors.

A.1.a.2. Analyze formulation and emissions data for products and materials used

indoors to determine likely chemical exposures indoors.

Another source of information on chemicals that may lead to exposures indoors is

formulation and emissions databases for products and materials used indoors.

Some data are available on product formulations through voluntary industry

disclosure and, in rare cases, have been obtained through required industry

disclosure under the ambient air program of the Clean Air Act (CAA). However,

most of the available data on product formulations were obtained prior to 1990,

which limits their usefulness. Data for some chemical exposures may also be

obtained through current programs such as the EPA Voluntary Children’s

Chemical Evaluation Program (65 FR 81700), which provides data on exposures

to 23 chemicals to enable the public to better understand the potential health risks

to children, or through work with the Organization of Economic Cooperative

Development (OECD) to develop emissions scenario documents for products. 

Another source of product formulation data is Material Safety Data Sheets

(MSDSs); however, these data sheets may not list all the potential chemicals of

concern in a product or material used indoors. For a more limited number of

products and materials, emissions data are available in the literature through
U.S. EPA, 402-B-05-001, March 2005 7

chamber or field studies. Formulation and emissions databases for products and

materials are particularly useful where the data have been used in indoor air

quality models to assess potential concentrations, and related exposures, indoors.

A.1.a.3. Evaluate levels of pollutants that may result from particular exposure

scenarios of concern.

Studies such as BASE, which evaluate the typical concentrations of chemicals and

mixtures indoors, do not effectively address the high level exposures that may

occur under special circumstances. For example, high level exposures may occur

during the use or storage of specific products or materials within the indoor

environment; in some cases, these may come from areas external to the living area

(e.g., from attached garages or parking areas, or from commercial facilities located

within a building). In addition, exposures from external sources may be of

concern, including emissions from stationary or mobile sources, particularly those

in close proximity to a building, or penetration of chemicals through soil. 

Monitoring studies, or source characterization studies (see section A.1.d), are

needed to more fully address the both the acute and chronic exposures that may

result from particular exposure scenarios of concern. 

A.1.a.4. Further develop and refine personal monitoring techniques and equipment

for use indoors.

Stationary monitors set up at fixed sites in a building may not accurately represent

the actual exposures that occur to individuals in the building. For example, a

person using a consumer product in a bedroom may receive a much higher

exposure to the product than would be indicated by a monitor set up on the other

side of the bedroom or in the kitchen. For this reason, personal monitors have

been designed to be worn or carried by individuals to more accurately record the

their exposures. The development of improved personal monitors that are less

cumbersome for users to wear and that can accurately sample for a broader range

of chemicals is needed. In addition, the research is needed to develop and

establish recommended sampling methods for these devices.

 

A.1.b. Determine hazards and dose-response indices for chemicals and mixtures found in

indoor environments.

Even if we knew the levels of chemicals and mixtures that occur indoors under a broad

range of exposure scenarios, we would be at a loss to determine their impact without

knowledge of the hazards of the chemicals and mixtures and the doses that may result in

health impacts. For several years, concerns about carcinogenicity have dominated

discussions about the risks posed by toxic substances. However, the noncarcinogenic

effects on organs and organ systems may pose an equal or greater threat to public health.

Some of the targets of these effects to consider include the respiratory system,

cardiovascular and cardiopulmonary systems, the reproductive system, and the nervous

system. Developmental effects may also be of concern. In particular, there is a need to
8 U.S. EPA, 402-B-05-001, March 2005

develop toxicity data for chemicals and mixtures that may be relevant to potentially

susceptible life stages including pregnant women, infants and children, and the elderly. 

Dose-response data are not available for many of the volatile organic chemicals and

mixtures found in the indoor environment, although some steps have been taken in recent

years to obtain such data through programs like EPA’s High Production Volume (HPV)

Initiative Program (65 FR 81686), a program to obtain basic screening-level hazard data

for chemicals produced or imported in quantities exceeding 1 million pounds per year,

and the VCCEP. Even when data are available, they are generally based on a less than

comprehensive review of the health effects of the chemicals and mixtures. To help in

prioritizing the health effects data needed, an analysis of the available monitoring data

should be performed to help target chemicals for evaluation in laboratory or

epidemiological studies (e.g., chemicals that are unlikely to be highly toxic, based on

structure-activity relationships, and that are found at very low levels indoors would be

given lower preference for further toxicological testing). 

Several inorganic compounds are not adequately characterized from a health effects

perspective including combustion byproducts such as nitrogen dioxide (NO2) and carbon

monoxide (CO). A thorough analysis of the current literature, as well as additional

research, is needed to fully assess the respiratory effects of NO2 at levels expected to

occur in the indoor environment and also the potential association between respiratory

illnesses and symptoms and elevated NO2

 levels. These respiratory illnesses and

symptoms include chronic obstructive pulmonary disease in adults; asthma, the increased

occurrence of respiratory infections, and the increased sensitivity to inhaled allergens,

particularly in children; and the potential for the development of diarrhea and other nonrespiratory symptoms in infants. In addition, more research is needed on the potential

morbidity associated with low-level CO exposures, the potential mechanisms of CO

toxicity unrelated to hemoglobin binding, and the impact and mechanisms of CO

exposure on potential highly-susceptible populations (e.g., the elderly, infants, and

persons with heart, lung, or blood disorders).

Further research is also needed to determine if chemical allergens, irritants, fragrances, or

odors can potentially cause or trigger asthma.

 

A.1.c. Prioritize chemicals and mixtures of concern and select a small number for further

study.

The purpose of the prioritization should be to select a handful of chemicals or classes of

chemicals that will undergo a more extensive analysis, as detailed under sections A.1.d

through A.1.h. For some chemicals, the research sequence described by sections A.1.d

through A.1.h. may not fully apply, as the initial chemical assessments may reveal that

certain steps may be bypassed due to the availability of existing information.

EPA already has programs to address two high-risk components of indoor air, radon and

environmental tobacco smoke (ETS). EPA needs to develop a generally acceptable

system for prioritization of chemicals of concern, other than radon and ETS. Although the
U.S. EPA, 402-B-05-001, March 2005 9

prioritization will focus on potential relative risks of chemicals and mixtures in indoor

air, the prioritization scheme may be expanded to include dermal exposures as well as

inhalation exposures. One approach is to look at monitored levels of the chemicals in

indoor environments. Another approach is to consider the development of prioritization

systems based on the formulations or emissions of products and materials used in the

indoor environment, in conjunction with modeling to determine potential concentrations.

We may also use biomonitoring data to assist in prioritizing chemicals or mixtures of

concern. However, although biomonitoring data are useful in determining those

chemicals and mixtures that are a concern from the standpoint of cumulative exposures,

additional analyses would be needed to determine the contributions to these cumulative

exposures occurring through the indoor environment. Biomonitoring data may help us,

however, to narrow the list of chemicals and mixtures of concern. EPA must also

continue to evaluate and compare the exposures and risks that may occur due to specific

scenarios of concern (e.g., ‘hot spots’ with untypically high exposures), so that we do not

neglect high-exposure scenarios of concern and other known risks.

Based on this prioritization, specific chemicals or mixtures would be selected for further

study.

A.1.d. Characterize the sources of the chemicals and mixtures selected in A.1.c.

A.1.d.1. Determine potential sources of selected chemicals and mixtures.

Specific research to determine the sources of the chemicals and mixtures selected

will vary. For example, if a chemical is chosen based on product formulations or

emissions or on specific scenarios of concern, the source(s) of the chemical or

mixture will already be known. However, further source characterization studies

may be needed to more accurately determine emissions factors for these sources

under differing conditions.

If chemicals and mixtures are chosen from a prioritization scheme using

monitoring data (Section A.1.c) or because of health concerns at levels in the

indoor environment, data needed will depend on the properties of the chemical or

mixture. For chemicals that are unlikely to be produced through natural processes

or through breakdown of products or materials indoors (e.g., methylene chloride),

source information can be obtained through (1) a market analysis of products and

materials formulated using that chemical or mixture, (2) a search of databases

containing product formulation data, (3) a search of data from indoor air source

characterization studies, etc. For chemicals that may have natural sources or that

may be formed by the breakdown of products or materials, combustion processes,

or chemical interactions (e.g., formaldehyde), source characterization is more

complex, and will rely upon both the information sources mentioned above and a

further literature review of potential mechanisms of increased indoor

concentrations.
10 U.S. EPA, 402-B-05-001, March 2005

A.1.d.2. Develop quantitative emissions factors by source.

In many cases, the data available will provide only an indication of potential

sources of exposure; they will not provide the quantitative data on emissions

factors that are needed to do an exposure assessment. Therefore, research will be

needed using chamber or test house studies, or through the development of

emissions models (e.g., based on chemical formulations), to determine emissions

factors for exposure scenarios of concern.

A.1.d.3. Determine cumulative exposures.

In addition to the characterization of indoor sources of the chemicals and

mixtures, research is also needed to determine the amount of the chemicals and

mixtures found indoors that may be from ambient air, track-in from outdoors,

food, water, soil, and other potential sources. 

 

A.1.e. Study the indoor fate of the chemicals and mixtures selected in A.1.c.

Research on the fate of the chemicals and mixtures of concern will be highly dependent

on the substances themselves (i.e., their likelihood of penetrating the building envelope;

of being adsorbed to, and re-emitted from, materials indoors; and of interacting with other

chemicals or mixtures in the indoor environment). Research is also needed to better

understand the impact of reactive contaminants on the indoor environment. Reactive

contaminants have the potential to react with other components of the indoor

environment to form ‘new’ pollutants (usually chemicals or particulate matter) (Weschler

and Shields, 1997, 1999). For example, several reports have shown that low levels of

ozone react with some volatile organic compounds in the environment to produce

chemical pollutants and particulates that are associated with health impacts including

respiratory system irritation. Some highly-used chemicals and products are of particular

concern because of the reactive nature of the resulting compound produced when ozone

reacts with these substances (e.g., limonene or other terpenes, decomposition products of

printer/copier toner powder, and building materials that contain an unsaturated carboncarbon structure). The chemical structures of all the potentially formed species and their

impact on health are not yet known and should be evaluated under research needs

described in sections A.1.b. and A.1.g.

Although understanding the fate of chemicals in the indoor environment may be

important in determining the actual exposures that may occur from chemicals and

mixtures indoors, these data are difficult and time-consuming to obtain. It may be

necessary, in the short term, to estimate the effects of these processes indoors while we

await the results of this research. Therefore, this research should have secondary

importance to the research in sections A.1.a through A.1.d, and sections

A.1.f through A.1.h.
U.S. EPA, 402-B-05-001, March 2005 11

A.1.f. Perform exposure assessments for the chemicals and mixtures selected in A.1.c.

A.1.f.1. Determine and compare cumulative exposures.

Research will be needed to determine the exposures that may occur with the

chemicals and mixtures of concern. If there appear to be scenarios where high

levels of the chemical or mixture may occur over short time periods, acute

exposures should be assessed, as well as chronic exposures. If not, analyses of

chronic exposures alone may be sufficient. Data on sources, estimated

concentrations, and time-activity patterns should be combined to estimate these

exposures. Where concentration data are not directly available through

monitoring, modeling can be used to estimate exposure concentrations if data are

available on emissions factors for the chemicals and mixtures. Although the focus

of the exposure assessments will be on indoor air exposures, the relative

exposures from other media (ambient air, track-in from outdoors, food, water,

soil, etc.) should also be estimated; if exposures from other media account for a

disproportionate exposure as compared to those from indoor sources, further

assessment of exposures from indoor sources may not be required. 

The initial exposure assessments will be less detailed, and will be refined as the

key pollutant sources and routes of exposure are determined. More detailed,

follow-on exposure assessments will only be required if the risks estimated based

on the initial exposure assessments warrant further study (see section A.1.g.) and

should focus on scenarios that appear to result in the greatest exposures based on

the initial assessments.

A.1.f.2. Develop more refined assessments of exposure variations by population.

Although there have been a number of studies looking at time-activity patterns for

the general population (Klepeis, Tsang, and Behar, 1996), less is currently known

about demographic or geographic variations in product use (e.g., differences in

product use by certain cultures or occupations or differences in pesticide use

across the country) or variations in product use across building types

(e.g., differences in the cleaning products used, or differences in pressed wood

use, in homes versus office buildings). Further research on variations in both acute

and chronic exposures are needed in these areas. The evaluation of any possible

increased exposures, both demographically/geographically and by building type,

for particular susceptible populations (e.g., infants and children, pregnant women,

the elderly, those with asthma, etc.) is also an area of needed research. In some

cases, EPA may be able to work with industry to obtain such information on a

voluntary basis; in other cases, it may be necessary to survey for this information. 

Depending on the chemicals and mixtures selected, their sources, and the level of

detail needed in the assessments, evaluation of these factors may be more or less

important.
12 U.S. EPA, 402-B-05-001, March 2005

A.1.f.3. Further develop and refine exposure modeling tools and assessments.

This exposure assessment work may also require further development and

refinement of exposure modeling tools such as indoor air quality models.

In addition, the results of these assessments should be transferred, as appropriate,

to inform other exposure modeling efforts within the Agency (e.g., the Hazardous

Air Pollutant Exposure Model [HAPEM] being used for the National Scale

Assessment, and community-based modeling assessments).

 

A.1.g. Assess risks for the chemicals and mixtures selected in A.1.c.

Risk assessments should be performed by combining data on exposures (section A.1.f.)

and dose-response indices (section A.1.b.) for the selected chemicals and mixtures. As

with the exposure assessments, initial risk assessments should be less detailed; more

detailed assessments should be performed, as warranted, for any significant risk

scenarios. In addition, the relative risks from exposures in various media should be

assessed; if management of risks due to exposures from other media (ambient air, track-in

from outdoors, food, water, soil, etc.) is more effective in reducing risk, further

assessment of risks from indoor sources may not be required. When possible, the risks to

certain susceptible populations, such as pregnant women, infants and children, and the

elderly, should be assessed.

A.1.h. Perform research on methods to manage risks for the chemicals and mixtures

selected in A.1.c.

A.1.h.1. Determine the need for development of risk management methods.

This research will be dependent on results from section A.1.g. In many cases,

further research will be needed to determine the most efficient and cost-effective

methods to reduce risk, however, if the risks from a chemical or mixture found

indoors do not appear to be significant or if the risks occur in large part through

another mode of exposure (e.g., ambient air or pesticide track-in), research efforts

may be better spent elsewhere. Even if the risks from an indoor source(s) are

substantial, further research on methods to manage risks may not be warranted

(e.g., there are obvious things that can be done to substantially reduce exposures

and risks). In addition, for the case in which the chemical or mixture of concern is

a HAP, the potential reductions in exposure due to regulatory actions should be

taken into account before determining the need for additional voluntary risk

management research.

A.1.h.2. Perform research to determine the most effective methods for voluntary

reduction of risks.

If research to manage risks appears warranted, initial research efforts should focus

on voluntary actions that might be taken to reduce risks. Risk management

research will be dependent on the sources of concern, and may include the
U.S. EPA, 402-B-05-001, March 2005 13

following options, among others: (1) assessments of risk reductions through

voluntary reformulations of products by industry or the use of alternative products

which are judged as “safer,” (2) evaluations of the effects of changes in industrial

processes on emissions and the related risk reduction, (3) analyses of the

effectiveness of the use of “best practices” to reduce risks, (4) analyses of the

effectiveness of increasing ventilation or affecting building pressure differentials;

(5) voluntary actions taken by consumers and businesses to alter behavior or

practices, (6) assessments of the economic benefits of risk management options,

(7) evaluations of the effectiveness of market incentive programs, and

(8) assessments of the impact of educational and outreach programs, including

programs such as “Read the Label.” Efforts should be made to set up formal

voluntary programs with industry, both to obtain needed data to develop

appropriate risk management options and to assist us in achieving risk reductions.

Also, although source modification or substitution may be the “best” option for

reducing risks, it may take several years to implement. Therefore, quick and

inexpensive options should be investigated in the interim.

Program Applications for Chemicals Research:

Fundamental to reducing risks from exposures to chemicals and mixtures in any environment is

the identification of pollutants of concern and the assessment of sources, fate, exposures, and

risks. Many EPA program offices are involved in projects to collect data on, and to assess the

exposures, risks, and risk management options for chemicals and mixtures that may be emitted

from products and materials indoors or that may infiltrate the indoor environment from outdoors.

Suitable cross-program strategies for research on chemicals and mixtures in the indoor

environment are needed to address a wide array of program interests. For example, ORIA has the

general need to respond to public inquiries, and to provide information and training to numerous

audiences, about the potential impacts of chemicals and mixtures in the indoor environment and

methods that can be used to reduce exposures and risks. In addition, as implementation of the air

toxics sections of the Clean Air Act moves towards a more risk-based process, it is important that

ORIA works with OAQPS and OTAQ so that indoor sources and exposures are appropriately

combined with those outdoors in an integrated strategy. This research would provide information

about indoor exposures and risks that are needed to integrate indoor and outdoor air toxics

strategies, and design those strategies to minimize total human exposures from both

environments. Other offices with a need for research on chemicals and mixtures indoors include

OPPTS, which is working to develop guidance for Federal facilities on the selection of products

and materials for use indoors; OSWER, which is concerned with the infiltration of hazardous

chemicals into buildings through soil; and OCHP, which is concerned with exposures to infants,

children, pregnant women, and the elderly in the indoor environment. 
14 U.S. EPA, 402-B-05-001, March 2005

References for Chemicals Research:

Kepleis NE, Tsang AM, and Behar JV. 1996. Analysis of the National Human Activity Pattern

Survey (NHAPS) Respondents From the Standpoint of Exposure Assessment: Percentage of

Time Spent, Duration, and Frequency of Occurrence for Selected Microenvironments by

Gender, Age, Time-of-Day, Day-of-Week, Season, and U.S. Census Region. Final Report.

Washington, DC: Office of Research and Development, U.S. Environmental Protection

Agency. EPA/600/R-96/074.

U.S. Environmental Protection Agency (U.S. EPA). 1998. A comparison of indoor and outdoor

concentrations of hazardous air pollutants. Inside EPA, Spring/Summer 1998. Research

Triangle Park, NC: Office of Research and Development, U.S. Environmental Protection

Agency. EPA/600/N-98/002. 

Wallace LA. 1987. The Total Exposure Assessment Methodology (TEAM) Study: Summary and

Analysis: Volume I. Washington DC: Office of Acid Deposition, Environmental

Monitoring and Quality Assurance, Office of Research and Development, U.S.

Environmental Protection Agency.

Weschler CJ, and Shields, HC. 1999. Indoor ozone/terpene reactions as a source of indoor

particles. Atmospheric Environment. Vol. 33, pp 2301-2312.

Weschler CJ, and Shields, HC. 1997. Potential reactions among indoor air pollutants. 

Atmospheric Environment. Vol. 31 (21), pp 3487-3495.
U.S. EPA, 402-B-05-001, March 2005 15

A.2. BIOLOGICAL CONTAMINANTS

Background Information:

Indoor biological contaminants can have adverse impacts on human health. Bacteria, viruses,

fungi/ molds, pets, rodents, cockroaches, and dust mites may all contribute to the contamination

of indoor environments. In many cases, the presence of these contaminants is associated with a

transient or long standing moisture problem, which supports the growth of fungi, dust mites, and

certain bacteria, or they may result from the presence of a pet or pest infestation. To a limited

extent, biocontaminants may be blown in from outdoors, or carried in on people’s hair or

clothing. In addition, biocontaminants may be purposely introduced into a building as an act of

terrorism, an issue which has recently emerged as a national priority.

Biocontaminants can cause a variety of allergic or infectious diseases. Fungi also produce

irritants and in some cases potentially toxic substances (mycotoxins). Pets, rodents, cockroaches,

mold, and dust mites are known to be asthma triggers. Some of the most serious and potentially

fatal building related illnesses are caused from exposure to indoor biological contaminants.

These include Legionnaires disease, hypersensitivity pneumonitis, and allergic asthma. The

extent to which exposure to these contaminants indoors can be or should be reduced, and under

what circumstances, has great consequences for public health. 

Over the past few decades, we have seen an unprecedented rise in asthma, allergic rhinitis, and

other allergic diseases. However, the reasons or causes for this rise are unknown. Millions of

dollars are spent yearly on medications, devices, and doctors appointments to address indoor

allergy issues. It is estimated that more than 50 million Americans have allergic diseases

(AAAAI, 1996-2001) and that in 1996 chronic sinusitis affected more that 38 million Americans

(CDC, 2002). In fact, allergic diseases are the 6th leading cause of chronic disease in the U.S.

and allergies cost health care systems more than18 billion dollars per year (AAAAI, 1996-2001).

Economic costs for allergic rhinitis alone, estimated for 1993, were 3.4 billion dollars (Storms,

Meltzer, Nathan et al., 1997).

In addition, buildings have changed over the years - with the advent of new construction

techniques, new building materials, tighter building envelopes, and reduced outside air

ventilation, the incubation and transmission of infectious diseases through the indoor

environment is of growing concern. This is of particular concern in buildings with high occupant

density such as schools. 

Unfortunately, our knowledge of the relationships between building conditions, occupant

exposures, and health consequences is limited, as is our knowledge of viable means to effectively

mitigate exposures and health impacts. Nevertheless, because of the public health impact of

biocontaminants, there is considerable interest in producing information and guidelines to the

public, the building industry, and to public health authorities. In response, the EPA has provided

some limited guidance, mostly under the premise that reducing exposure is an appropriate

response. But while there are little hard data and the true efficacy of such an approach is not

known, organizations such as the National Academy of Sciences recommend proceeding with

exposure reduction measures for indoor asthma triggers rather than waiting until all desirable
16 U.S. EPA, 402-B-05-001, March 2005

research is performed (NAS, 2000). Asthma and allergy sensitization and exposure reduction

measures are discussed in additional detail in section A.3.

Program Needs for Biological Contaminants Research:

A.2.a. Conduct research for specific biocontaminants.

A.2.a.1. Conduct studies on mold allergens and mycotoxins. 

Mold allergens

Mold allergens are important asthma and allergy triggers. Research is needed to

obtain more information on the characteristics and health-related issues associated

with mold allergens. Research should identify the specific fungal proteins that

cause allergic response. Standardized and quantitative methods to assess mold

exposure are important efforts, which should include studies to establish

biomarkers of exposure to mold in humans (or surrogate biomarkers) in order to

assist researchers and medical personnel in assessing mold exposures. Research

should identify patterns of cross-reactivity among fungal allergens and the relative

potency of different antigens.

Mycotoxins

Research is needed to obtain more information on the characteristics and healthrelated issues associated with mycotoxins, including work which directly

correlates mycotoxin exposure by the inhalation route with human health effects.

The health effects resulting from inhalation exposure to mycotoxins are largely

unknown; ongoing research on these health effects is important, and should

continue.

A.2.a.2. Conduct studies on allergens from rodents and rabbits.

Research is needed to develop a better understanding of biological contaminants

that originate from rodents (e.g., rats and mice) and rabbits. Studies should assess

the degree to which rodent/rabbit exposures in the home exacerbate and/or cause

asthma in sensitized asthmatics.

A.2.b. Assess the effects of early-life exposures on the development of the immune system.

One theory regarding the development of asthma from an environmental exposure

involves the developing immune system. During early life, an environmental exposure (or

exposures) may push the immune system to develop in such a way that the risk of

developing asthma is increased. Some studies, however, indicate that early childhood

exposure to some contaminants (e.g., allergens, microbes, and their products such as

endotoxin) can be protective, and may reduce the chances of developing asthma.

It is theoretically possible that EPA’s guidance for reducing exposure to biological

contaminants, particularly during infancy/early childhood while the immune system is
U.S. EPA, 402-B-05-001, March 2005 17

developing, could be counterproductive for some indoor biological pollutants. More

information is needed regarding the effects of early-life exposures on the immune system

and the potential that the lack of exposure during infancy can increase atopy in some

individuals. This is especially critical because it may help explain the rapid rise in allergic

diseases, and it has the potential to strongly influence the EPA’s outreach messages

related to asthma and other allergic diseases. The role of breast milk in this process

should also be considered.

A.2.b.1. Conduct early-life exposure studies for endotoxin.

Endotoxin comes from the outer membrane of gram-negative bacteria. Endotoxin

can be found in household dust in both urban and rural settings. People are

exposed to low levels of endotoxin on a continuing basis since gram-negative

bacteria are ubiquitous. Endotoxin is a potent stimulant of the immune system,

and it is possible that endotoxin exposure has both positive and negative effects,

depending upon age of exposure and other factors. Some studies suggest that early

exposure to endotoxin can be protective against asthma, but that later life

exposure can exacerbate existing asthma. In the case of dust mite exposure, early

life exposure can clearly cause asthma, but for other biological pollutants such as

endotoxin, we do not have enough information to make a determination on the

effects of early exposure. Studies are needed to determine what effects, if any,

that early-life exposure to endotoxin has on the developing immune system.

A.2.b.2. Conduct early-life exposure studies for other environmental factors.

Other exposures which may affect a developing immune system during early-life

include infectious diseases, parasites, and other biological contaminants such as

dog/cat allergens. Research should include single pollutants as well as mixtures of

chemical and biological contaminants. A first step in this research area could be to

convene an expert panel to identify and prioritize the environmental factors and

contaminants that should be considered, followed by appropriate research to

evaluate the potential health impacts such as allergic and asthma-like conditions.

Program Applications for Biological Contaminants Research:

The rapid rise in the incidence of asthma and other allergic diseases is yet unexplained. 

We know that some common allergens are biological, and that exposure to some of these

allergens occurs primarily indoors. This makes allergic diseases both medical and indoor

environmental problems. On the specific issue of mold, there is some epidemiological evidence

that the existence of mold and/or dampness in the home increases the risk of respiratory

symptoms - this ongoing research is important and should continue. The balance between

humidification and dehumidification of indoor environments needs to be assessed in conjunction

with appropriate control of mold growth (see section D, “Building Design and Operation). 

The ability to understand the relationship between mold exposure and health is a foundational

issue and requires that techniques to reliably and accurately assess mold exposure be developed.
18 U.S. EPA, 402-B-05-001, March 2005

References for Biological Contaminants Research:

American Academy of Allergy, Asthma and Immunology (AAAAI). 1996-2001. The Allergy

Report: Science Based Findings on the Diagnosis and Treatment of Allergic Disorders. 

Centers for Disease Control (CDC). 2002. Fast Stats A-Z, Vital and Health Statistics, Series 10,

No. 200, Table 57. 1996 as cited in NIAID (National Institute of Allergy and Infectious

Diseases). January 2002. Allergy Statistics, Fact Sheet.

National Academy of Sciences (NAS), Institute of Medicine. 2000. Clearing the Air, Asthma and

Indoor Air Exposures. Washington DC: National Academy Press.

Storms W, Meltzer E, Nathan R, and Selner J. 1997. The Economic Impact of Allergic Rhinitis. 

Journal of Allergy and Clinical Immunology. 99:S820-4.
U.S. EPA, 402-B-05-001, March 2005 19

A.3. SENSITIZATION, ALLERGY AND IRRITATION HEALTH EFFECTS

Background Information:

Exposure to certain levels of specific pollutants may cause an individual to become increasingly

susceptible to respiratory reactions upon further exposure to those or other pollutants. 

This applies to a broad spectrum of pollutants, including chemicals (see also A.1),

biocontaminants (see also A.2) and particulate matter (see also A.4). This enhanced

susceptibility is referred to as sensitization and may be reported as a positive allergen test

response. For example, most studies have shown an association between exposure to dust mite

and cockroach allergens above certain levels and an increased prevalence of sensitization. Some

studies have reported this association for cat and dog allergens, whereas others have not found an

association for these allergens. Several studies have reported clear dose-response relationships

between the allergen levels and sensitization. Atopy or genetic disposition has also been strongly

associated with sensitization potential. In contrast to sensitization, there is a “hygiene

hypothesis” or “dirt hypothesis” that suggests that the human immune system development is

affected by reduced exposure at birth and in early life to certain contaminants (see A.2.b).

There is a large and ever growing body of current literature related to the influence of indoor

pollutants such as dust mites, pet dander, molds, cockroaches, and environmental tobacco smoke

on asthma or allergy symptoms. The association between these indoor contaminants and the

exacerbation of allergies and asthma is well-established. For dust mites and environmental

tobacco smoke, there is also strong data to support an association between exposure to the

contaminant and initiation of asthma or allergy symptoms. Several primarily outdoor air

pollutants have also been linked to asthma and other adverse respiratory conditions, including

sulfur dioxide, nitrogen dioxide, ozone and particulate matter including acid aerosols. Although

there is a large body of current data on the impact of environmental exposures on asthma and

allergies, the results of many of the studies are limited by problems with inconsistencies in

disease diagnosis, design of study, or inappropriate consideration of confounders. In addition,

there are potentially several different variations (phenotypes) of asthma and allergies, and

different treatments or mitigation methods may be required. 

Several contaminants found in the indoor environment can directly or indirectly induce allergic

respiratory reactions, while other contaminants cause respiratory symptoms through non-allergic

mechanisms such as irritation. Most allergens stimulate production of immunoglobulin E (IgE)

antibodies that can result in various hypersensitivity reactions. There also appear to be chemical

compounds with a capacity to trigger inflammation without involving IgE. 

Program Needs for Sensitization, Allergy and Irritation Health Effects Research:

A.3.a. Investigate relationships for pollutant exposure levels and sensitization.

Although there is strong support for a relationship between some pollutant exposures

above certain levels and sensitization in particular populations, research is needed to

more fully assess the exact relationships between exposure, sensitization, asthma, and/or

other respiratory morbidity variables. The sensitization process, as well as the thresholds
20 U.S. EPA, 402-B-05-001, March 2005

of exposure and other potentiating conditions that can trigger a response, exacerbate an

existing disease, or induce a new or unidentified disease state are of critical interest. 

Research should also investigate whether combinations of allergens affect sensitization.

A.3.a.1. Characterize exposure thresholds that sensitize individuals and those that

trigger allergic reactions to pet and cockroach allergens.

Pet allergens and cockroach allergens are difficult to control because of their

adhesive and aerodynamic properties. In addition, pet allergens tend to be

ubiquitous and travel readily between environments on people’s clothing, and

cockroaches can infest a dwelling from an adjacent dwelling or building. Thus,

significant exposure reduction for these allergens is difficult to achieve. 

Knowledge of the thresholds for sensitization and for triggering responses would

help determine the degree of avoidance and mitigation that is critical so that

proper guidelines can be established. 

A.3.b. Conduct characterization studies of allergens and chemical irritants.

Although the literature concerning allergic reactions and allergens has greatly advanced in

recent years, research is needed to address data gaps with regard to the mechanisms of

action of various allergens on the respiratory system. Research is also needed to address

limitations and gaps in available information regarding specific actions of irritants on the

respiratory system. Some of the major data gaps in the available literature for both

allergens and irritants involve the specific characteristics of inflammatory processes;

the exact mechanism of action of contaminants on the respiratory system; the long-term

role of continued exposure to contaminants on persistent lung conditions; the possibility

of differential impacts of exposure on potentially sensitive populations such as children

and the elderly; efficacy and effectiveness of mitigation methods; and, the role of

avoidance or mitigation to symptom or disease improvement. Research is also needed to

further investigate the concept of total allergic burden, and whether exposure to lowlevels of multiple allergens simultaneously (or within a short time period) affect health

endpoints. 

A.3.b.1. Investigate allergy and irritancy issues for occupational contaminants in

other indoor environments. 

Several allergens and chemicals that have been shown to cause allergy or asthma

in occupational settings have not been well-studied in other typical indoor

environments (e.g., residences and schools). For example, mouse allergen is a

well-defined cause of IgE-mediated hypersensitivity in occupational settings, but

although it is known that mouse allergen is widely distributed in inner-city homes

where allergy and asthma prevalence is high, little information is available on the

impact of the level of mouse allergen found in homes on the respiratory system of

susceptible individuals. Further study is needed to assess the clinical importance

of this potentially significant and under-recognized indoor allergen. Similarly, rat

and rabbit allergens are known to cause allergies and asthma in occupational
U.S. EPA, 402-B-05-001, March 2005 21

environments, but further research is needed to assess these contaminants in other

indoor environments. 

A.3.c. Determine the efficacy of exposure reduction measures recommended in existing

EPA guidance.

The EPA currently recommends reducing or eliminating exposure to indoor asthma

triggers to reduce the likelihood of asthma symptoms indoors. There is insufficient data

to support the effectiveness of this approach. Research is needed to fill this data gap, and

to assess critical issues such as whether reducing exposure to indoor contaminants

reduces the potential for sensitization, and whether occupant age or other population

characteristics are significant factors. One example of research that could be performed

in this area includes assessing whether the removal of a dog or cat from a home results in

a sufficient decrease in overall allergen exposure to decrease allergic symptoms in

sensitized individuals. Similar research could be performed for other exposure reduction

measures.

A.3.d. Conduct studies to determine the most effective mitigation techniques to achieve

sub-threshold levels for allergens and irritants.

Studies are needed to evaluate potential mitigation strategies for reducing exposures to

allergens and irritants. For each strategy, research should evaluate the effectiveness in

reducing exposure, the net improvement in health conditions, cost-effectiveness, ease-ofimplementation, and applicability to various indoor environments. Given the variable

nature of human immune systems, occupants will likely have varied responses to indoor

allergens and irritants, and a sufficiently ‘clean’ or ‘mitigated’ room may not be the same

for all occupants. Studies would need to determine whether there are practical ways of

reducing exposures in various contaminated environments below the required thresholds,

or whether a complete change in environment may be necessary.

Program Applications for Sensitization, Allergy and Irritation Health Effects Research:

The EPA seeks to educate health care providers and the public about the importance of having a

balanced approach to asthma management involving both medication and environmental controls

(trigger avoidance). Many of the trigger avoidance strategies currently used are based on the

concept that exposure reduction will alter symptoms, even though additional scientific evidence

as to the efficacy of such strategies is needed. Furthermore, the National Academy of Sciences

recommended that, although more research is needed, these exposure reduction measures should

be implemented rather than waiting until all desirable research is performed (NAS, 2000). 

In addition, a troubling question is the issue of whether some exposures may be needed to

prevent sensitization and allergic response. And for those exposures for which it truly is

advisable to mitigate, how much mitigation is necessary or feasible are open questions. 

Knowledge as to how exposure to certain allergens affects human responses, and what threshold

levels must be achieved to avoid an allergic response is of critical concern. The proposed

research is designed to provide information needed to identify and promote effective

environmental control strategies. 
22 U.S. EPA, 402-B-05-001, March 2005

References for Sensitization, Allergy and Irritation Health Effects Research:

National Academy of Sciences (NAS), Institute of Medicine. 2000. Clearing the Air, Asthma and

Indoor Air Exposures. Washington DC: National Academy Press.
U.S. EPA, 402-B-05-001, March 2005 23

A.4. PARTICULATE MATTER

Background Information:

Airborne particulate matter (PM) refers to a large group of materials of diverse sizes and

chemical characteristics which share the ability to be transported in the air as discrete solid

particles or liquid droplets. These particles originate from a number of natural processes as well

as from some human activities, both indoors and outdoors. A large number of inorganic and

organic materials may be contained within these particles, including biological contaminants.

Epidemiological studies document a number of associations linking outdoor particulate matter

concentrations to adverse health effects such as decreased lung function, exacerbation of

respiratory diseases, and premature death. Studies on indoor air have also shown that particulate

matter is a significant indoor pollutant (e.g., EPA’s Particle TEAM study, and EPA’s Building

Assessment and Survey Evaluation [BASE] study). Indoor exposures to particulate matter can be

significant, and there is inadequate information as to whether indoor particles originate outdoors,

thus reflecting the epidemiological results above, or whether there is a substantial component

from indoor sources that would add to the health impacts from particle exposure. Of particular

concern are the growth of biological contaminants indoors, particulate matter from indoor

combustion appliances, and other potential indoor sources including printers and copiers. 

Furthermore, there is little known about the particle dynamics that could affect particulate matter

exposure. For example, there is believed to be a ‘personal cloud’ in which an individual’s

exposure to particles is not influenced solely by ambient contaminant levels, but also by particles

that become airborne due to one’s own physical activity. Information on these issues is needed

for the EPA to develop an effective program to mitigate exposure and risks from indoor

particulate matter.

An EPA program has been established to conduct particulate matter research, primarily from an

outdoor air perspective, to support review and implementation of EPA’s National Ambient Air

Quality Standards (NAAQS) for PM. Congress directed the EPA to arrange for an independent

study by the National Research Council (NRC). This study was intended to identify the most

important research priorities, develop a conceptual plan for particulate matter research, and

monitor and evaluate the research progress. NRC established the Committee on Research

Priorities for Airborne Particulate Matter in January 1998. This committee identified ten high

priority research topics and developed a 13-year integrated strategic plan (from 1998 to 2010) of

recommended research. 

While some of the indoor environments research needs for particulate matter may be addressed

by the NRC plan and EPA’s existing program for outdoor particulate matter research, there are

several key areas that require research specifically for advancing the EPA’s indoor environments

program. 
24 U.S. EPA, 402-B-05-001, March 2005

Program Needs for Indoor Particulate Matter Research:

A.4.a. Conduct research for particulate matter measurement techniques.

Particulate matter concentrations can be measured using different techniques and

measurement units. For example, one approach is to measure the particulate matter

concentration in particle counts per unit volume, while another approach entails

measuring the particle mass. Research may be needed to reconcile different methods to

ensure proper interpretation of data and inter-comparison of results. Some measurement

research is being conducted under the outdoor air particulate matter research program. 

Specific research is needed to develop appropriate measurement techniques for indoor

environments, which may have unique measurement error and other technical

considerations. Research is needed to determine the factors for the conversion from

particle number to mass for uncharacterized indoor aerosols. Specific research is also

needed on the development and verification of improved personal monitoring devices.

A.4.b. Develop particulate matter cumulative exposure models derived from specific

indoor particle source parameters, indoor transport mechanisms, indoor

contributions of outdoor sources, outdoor exposures, and human activity.

Outdoor air quality particulate matter exposure models are being developed, however

these models typically fail to account for indoor sources of particulate matter and many of

the issues identified in subsequent sections A.4.c.1 through A.4.c.3. Efforts are needed to

develop improved exposure models that accurately predict cumulative particulate matter

exposure by integrating outdoor exposures with indoor exposures, i.e., indoor exposures

that are based on both outdoor and indoor sources of particulate matter within the indoor

environment. Research could investigate linking/adapting existing indoor and outdoor

exposure models. There may be existing indoor air quality exposure models, such as the

CONTAM model developed by the National Institute for Standards and Technology

(NIST), which may be adapted or modified for particulate matter exposure modeling. 

A.4.c. Identify major indoor particulate sources for different indoor environments.

There is a need to understand the major indoor sources of particulate matter for homes,

schools and offices, and to identify other critical indoor environments where particulate

matter requires further investigation. A comprehensive study is needed of how sources

impact each other.

A.4.c.1. Quantify the contribution of indoor sources and outdoor sources to

particulate matter found indoors.

Particulate matter in the indoor environment can result from indoor sources, and

outdoor sources from which the particles are able to migrate indoors. Where

possible, this research should identify and characterize the predominant indoor

and outdoor sources of particulate matter, determine how sources impact each

other, and assess the relative contribution of the indoor and outdoor sources to
U.S. EPA, 402-B-05-001, March 2005 25

total PM exposure, as well as to total indoor PM exposure and total outdoor PM

exposure. Research should also identify reactive contaminants, mechanisms, and

devices (such as ozone generators) that lead to the existence of secondary particles

in the indoor environment. The resulting compounds and their toxicities need to

be fully characterized.

A.4.c.2. Investigate the ‘personal dust cloud’ phenomena.

The implications of the ‘personal dust cloud’ phenomena are largely unknown. 

Research is needed to evaluate how much an individual’s particulate matter

exposure is affected by localized personal activities that may either generate

particulate matter or increase particulate matter exposure by re-entrainment of

settled-out particulate matter, and evaluate the impact of other

individuals’‘personal dust clouds’ on exposure. Research is also needed to assess

the impact of the ‘personal dust cloud’ on health and to identify/develop low cost

ways to mitigate any such effect.

A.4.c.3. Investigate the chemical composition and size distribution of indoor

particulate matter.

In order to adequately assess particulate matter health risks and mitigation

techniques of indoor particles from both indoor and outdoor sources, information

is needed regarding the chemical composition and how it relates to particle size

and particle source. This research should differentiate between coarse, fine, and

ultra-fine particles. The differentiation between fine particles (less than 2.5um)

and ultra-fine particles (less than 0.1um) is required to infer the aerodynamic

properties of the particles in the distribution and ascertain the appropriate

effective disposition rate constant.

A.4.d. Determine the health effects and risks of indoor particulate matter.

Many studies have associated particulate air pollution with asthma exacerbations,

increased respiratory symptoms, decreased lung function, increased medication use, and

increased respiratory-related hospital admissions, among other health endpoints.

Although there is a strong association between particulate matter exposure and respiratory

symptoms, there are several areas that have not been fully evaluated, including the

mechanisms of action (i.e., direct impact of the particulate on respiratory tissues,

transport of allergen or irritant to tissues where it causes an effect, or receptor modulation

causing an inflammatory response), composition of particles or particle complexes,

concentrations of concern, and impacts of co-pollutants. Particulate matter has also been

strongly been associated with excess cardiopulmonary death; however, mechanisms of

action for this effect are debated in literature. Further information on these mechanisms

of action and the biological basis of these adverse health effects may help establish levels

of concern and health-based risk management options, especially for sensitive

populations. In addition, the populations that have been reported to be at increased risk

(e.g., the elderly, persons with pneumonia, heart diseases, and respiratory diseases) may
26 U.S. EPA, 402-B-05-001, March 2005

spend greater amounts of time indoors and may have an even larger component of their

total particulate matter exposure due to indoor particulate sources. 

The majority of available health effects information on particulate matter exposure is

based on studies of outdoor air. While considerable particulate matter health effects

research is being conducted under the auspices of the outdoor air particulate matter

research program, this research will likely need to be expanded to consider the particulate

matter that is determined to be most-characteristic of the indoor environment, particularly

from indoor sources (see sections A.4.c.1. and A.4.c.3). Additional research items 

include:

1. identifying the most-toxic indoor particulate matter contaminants;

2. investigating indoor particulate matter health effects for the general population

and for susceptible sub-populations;

3. investigating the deposition and fate of particles in the respiratory tract,

particularly for indoor biological contaminants (e.g., cockroach parts);

4. evaluating the health effects when particulate matter is combined with other

indoor pollutants.

A.4.e. Assess particulate matter mitigation strategies.

Recommended mitigation strategies will likely be dependent on the particulate matter sources

(physical characteristics and health impacts), the building design and operating characteristics,

and the occupants. For example, ventilation with outdoor air may be considered a mitigation

strategy for indoor particulate matter; however, there may be many situations where the indoor

particulate matter results predominantly from outdoor sources or where the outdoor ambient air

may require filtration or other treatment. 

There ultimately needs to be simple and cost-effective actions that the EPA can recommend for

the general population, and for sensitive and susceptible individuals, to reduce particulate matter

exposure in the indoor environment. In evaluating particulate matter mitigation strategies, the

research should consider the effectiveness in reducing particulate matter exposure, the net

improvement in health conditions, cost-effectiveness, ease-of-implementation, and applicability

to other indoor environments. Existing mitigation techniques that should be investigated can be

divided into strategies which are continuous (such as building design, building construction

features that limit the entry of outdoor particles, air filtration, and ventilation), intermittent

activities primarily involved with clean-up (such as high-efficiency vacuum cleaners, wet

mopping, hazardous particle removal, and changes in cleaning and maintenance practices), and

lifestyle changes (such as eliminating indoor smoking or getting rid of house pets). Additional

particulate matter mitigation strategies should also be investigated after the research described in

sections A.4.c.1 through A.4.c.3 yields information regarding specific indoor particulate matter

sources and exposure routes. 
U.S. EPA, 402-B-05-001, March 2005 27

Program Applications for Indoor Particulate Matter Research:

Particles are ubiquitous contaminants, but unlike chemical contaminants, outdoor and indoor

particles vary in size, shape, and chemical make-up. As a result, conclusions reached relative to

particles outdoors do not necessarily apply to particles indoors. In addition to the outdoors,

indoor sources of particles include material sources, biological sources, combustion sources, and

activity sources, such as vacuuming. While particles are a known health hazard, the extent of

that hazard indoors, or the types or sources of indoor particles creating that hazard remain

unknown. This research will enable EPA to provide substantive and detailed guidance for

controlling indoor particle exposures in ways that are effective in reducing risk. Research to

investigate particulate matter from indoor combustion appliances would directly support EPA’s

role in the international Partnership for Clean Indoor Air, particularly if the assessments include

exposures from indoor cooking fires, biomass stoves, kerosene, and liquefied propane gas.
28 U.S. EPA, 402-B-05-001, March 2005

B. HUMAN PERFORMANCE

Background Information:

Human performance refers to our ability to perform various generic mental and physical

functions such as reading/comprehending, calculating, remembering, typing, or driving. 

These tasks are inherent to how well we perform life’s functions at home, at school or at work. 

They have important social and economic value, and understanding how the quality of the indoor

environment enhances or inhibits our ability to perform life’s tasks is the subject of this

programmatic research need.

Evidence is accumulating that indoor air quality can have a measurable impact on human

performance. Early studies using survey data in which respondents estimate the effect of indoor

air on their productivity suggest that current conditions reduce productivity by 3%-4% on

average, or that personal controls of ventilation and temperature could improve productivity by

up to 6% and 10% respectively (U.S. EPA, 1989; Raw, Roys and Leaman, 1990). More recent

controlled field studies measuring performance of specific tasks suggest that increased pollution

sources or reduced ventilation can reduce human performance measures by 2%-6% (Wargocki,

Wyon, Baik et al., 1999). Further, a major cross sectional study of offices of a large U.S.

corporation found that 35% of short term sick absences could be attributed to low ventilation

conditions. The economic value of losses in human performance has been estimated to be in the

“tens of billions” of dollars (U.S. EPA, 1989) or $20 to $160 billion dollars per year (Fisk and

Rosenfeld, 1997).

While the potential value for improved human performance from improved indoor air quality

appears to be substantial, many methodological uncertainties make research in this field difficult. 

First, it is important to determine if the impact on human performance is biologically dependent

or independent of other health symptoms such as headaches or lethargy (i.e., is it the headache or

other health condition that causes performance to be effected?). Second, there is no generally

accepted method of measuring human performance in ways that are appropriate to different

indoor environments. Self assessed productivity through surveys is a convenient measure, but

there is only scant evidence that such measures accurately reflect true productivity. Various test

methods have been used to measure different aspects of mental and physical acuity (e.g., typing

test, memory test, arithmetic test), but without standardization, and it is difficult to compare

results across studies or to relate how such measures represent human performance in real world

conditions of different indoor environments. Research on the attributes of indoor air quality

parameters that impact human performance is needed before prescriptive guidance can be

formulated.

The long term program goals for research in human performance are to (1) understand the

biological mechanism by which indoor air quality affects human performance, and the

relationship (or lack thereof) between indoor air quality health symptoms and human

performance; (2) develop a general consensus on the metrics for measuring human performance

in various settings, and develop continuing research to improve those metrics over time;

(3) develop a database of information sufficient for statistically reliable inferences to support
U.S. EPA, 402-B-05-001, March 2005 29

guidelines or standards affecting indoor environmental parameters in homes, schools, offices,

hospitals, and other environments.

Program Needs for Human Performance Research:

B.1.a. Evaluate methods and define research agenda for measuring human performance.

Knowledge on the relationship between indoor environment parameters and human

performance are hindered by the lack of standardized measures. Establish a panel of

renowned scientists with expertise in the field of human performance measurements,

convened under the auspices of the National Academy of Sciences, the World Health

Organization, or similar body. The panel should review current theory and practice in the

measurement of human performance, recommend specific protocols for measuring 

human performance in a variety of settings (e.g., short term memory, motor ability,

cognitive abilities), and recommend a research agenda using these protocols. 

B.1.b. Develop dose-effect relationships for key contaminants on human performance

measures.

Ethical considerations inhibit experiments in which human subjects are exposed to

harmful contaminants, while animal studies that shows definitive performance

decrements in rats due to exposure to specific contaminants only provide indirect

evidence. However, some research suggests promising methods for extrapolation of

dose-effect relationships in animals to estimate the corresponding relationships in humans

(e.g., Benignus, 2001). The ability for cross-species extrapolation would greatly enhance

our ability to document and quantify the decrements in human performance associated

with indoor air pollution.

B.1.c. Quantify the relationship between health symptoms and human performance.

There are many studies relating occupant symptoms to building or air quality attributes

and this literature has been critically reviewed (Mendell, 1993; Seppänen, Fisk and

Mendell, 1999). However, there is little information about the relationship between health

symptoms and human performance, though there is some suggestion that decreases in

human performance do not take place until certain health symptoms such as headache

become evident (Wargocki, Wyon, Baik et al., 1999). This suggests that information on

the relationship between health symptoms and human performance combined with

available data on the relationship between building attributes and health symptoms could

be used to estimate human performance effects of building attributes. Quantifying the

relationship between building performance and health would provide a missing link in

our ability to quantify how building or air quality attributes affect human performance.
30 U.S. EPA, 402-B-05-001, March 2005

B.1.d. Quantify the relationship between building attributes and human performance

using both laboratory and field studies.

B.1.d.1. Conduct cross sectional studies to identify possible indoor parameters that

affect human performance.

Conduct cross sectional studies in which data from many buildings are

systematically compared in an attempt to derive statistical relationships between

IAQ relevant building parameters and performance/productivity variables. Such

studies would suggest relevant variables that could be more rigorously tested

through controlled studies. 

B.1.d.2. Conduct controlled studies to determine key indoor parameters that affect

human performance.

Conduct controlled studies in laboratories and in actual environments in which 

building or air quality parameters are systematically changed and human

performance measured to identify specific indoor air quality parameters that affect

human performance. Attempt to derive cause-effect relationships and

dose-response functions. Parameters of interest would include such things as

variations in specific source emissions, type and rate of ventilation air, personal 

controls of their microenvironment, air cleaning, intensity of housekeeping,

humidity/moisture controls, and thermal controls. Light (including daylight), noise

and ergonomic effects could also be studied.

B.1.d.3. Conduct studies to determine the efficacy of using self assessed performance

as a true measure of actual performance.

Since data on subjective measures are easier and more feasible to obtain,

knowledge of the relationship between subjective and objective measures can

greatly facilitate the use and interpretation of available data for guidance

development and decision-making.

B.1.e. Conduct research to examine the potential for improving productivity in schools

and offices through actions designed to improve human performance

B.1.e.1 Quantify the relationship between measures of human performance and

productivity in real world environments.

Human activity in the office or in school involve a complex combination of

mental and physical functions and tasks (e.g., reading, writing, calculating,

interpreting, reacting, communicating, typing), each of which may or may not be

affected by indoor air quality. Thus, while research on the relationship between

indoor air quality and specific elements of human performance (e.g., reading

comprehension) is important, it does not, in itself, capture the economic or social

value of performance changes in various indoor settings. Rather, the value of
U.S. EPA, 402-B-05-001, March 2005 31

performance changes is reflected through its impact on productivity. For example,

how much is productivity improved by a 10% decrease in typing errors in an

office setting, or how does a 10% improvement in short-term memory affect a

student’s performance in school? A set of experiments would be undertaken to

establish the relationships between changes in human performance and changes in

productivity in office, school, and home environments.

B.1.e.2 Conduct intervention and cross sectional studies to measure productivity

changes in schools and offices

The EPA and other organizations provide and promote guidance on good indoor

air quality practices that are expected to improve occupant health and

performance. This research would test the hypothesis that following good IAQ

practices in schools or office buildings will result in measurably higher

productivity, taking into account the need to reduce exposures from both indoor

and outdoor sources.

Program Applications for Human Performance Research:

The indoor air quality program is a non-regulatory program that depends on its ability to motivate

people to take actions that improve indoor air quality in their environments. Currently, however,

motivational messages must be related to improvements in health because this is where data are.

This is very limiting. The general public may be sensitive to health issues related to their homes,

but for other audiences such as office building managers, corporate executives, or school

administrators, improved health may be only a secondary concern to human performance and

productivity. To businesses, improved performance and productivity implies increased profits or

growth. To schools, student performance is a measure of educational system success. Thus,

developing information on how indoor air quality impacts human performance in offices,

schools, and other environments greatly expands the potential for indoor air quality programs to

effectively motivate the public to take action. The information from this research could

substantially energize the motivational potential of program material in virtually every program

area.

References for Human Performance Research:

Benignus, VA. 2001. Quantitative cross-species extrapolation in noncancer risk assessment.

Regul Toxicol Pharmacol. 34(1):62-8.

Fisk, WJ and Rosenfeld AJ. 1997. Estimates of Improved Productivity and Health From Better

Indoor Environments. Indoor Air: International Journal of Indoor Air Quality and Climate.

7: 158-172. 

Mendell, MJ. 1993. Non-Specific Symptoms in Office Workers: A Review and Summary of the

Epidemiologic Literature. Indoor Air: International Journal of Indoor Air Quality and

Climate. 3:227-236.
32 U.S. EPA, 402-B-05-001, March 2005

Raw GJ, Roys MS, and Leaman A. 1990. Further Findings from the Office Environment Survey:

Productivity, Proceedings of the Fifth International Conference on Indoor Air Quality and

Climate - Indoor Air 90. Vol 1. pp 231-236.

Seppänen OA, Fisk WJ, Mendell MJ. 1999. Association of ventilation rates and CO2

concentrations with health and other responses in commercial and institutional buildings. 

Indoor Air: International Journal of Indoor Air Quality and Climate. 4::226-52.

U.S. Environmental Protection Agency (U.S. EPA). 1989. Report To Congress on Indoor Air

Quality, Volume II: Assessment and Control of Indoor Air Pollution. Office of Air and

Radiation. EPA/400/1-89/001C.

Wargocki, P, Wyon DP, Baik YK, Clausen G, and Fanger PO. 1999. Perceived Air Quality,

SBS-Symptoms and Productivity in an Office at Two Pollution Loads, Proceedings of the

Eighth International Conference on Indoor Air Quality and Climate - Indoor Air ‘99. Vol 2.

pp 131-136.
U.S. EPA, 402-B-05-001, March 2005 33

C. IAQ MEASURES AND INDICES

C.1. BUILDING IAQ INDICES 

Background Information:

Current market forces and legal incentives for improving IAQ are absent largely because of our

inability to define IAQ by a simple measuring system, similar to the way energy can be

measured. In the absence of a convenient measure for IAQ, buildings can not be labeled or

categorized by their IAQ performance. IAQ is not easily marketed by owners, nor can tenants

conveniently negotiate for an IAQ upgrade during lease negotiations. In addition, insurers can

not conveniently adjust the insurance rates or mortgage companies adjust their finance rates on

the basis of IAQ. Nor does the research community have a convenient measure of IAQ that can

be related to health, property value, or productivity. For any market or program transaction to

incorporate IAQ, a convenient measure or measures are needed. This was recognized by the

Healthy Buildings Healthy People (HBHP) project that called for the development of an IAQ

index.

The pollution standards index (PSI) for outdoor air, or the UV index for sunlight are examples of

indices that greatly facilitate the valuation of risk conditions so that they may be easily

incorporated into decision and transactions. A variety of methods for constructing an index are

available and they vary from a simply linear weighting of input variables to more complex

structures. 

A building IAQ index can be designed to incorporate readily available information on IAQ

related building parameters such as ventilation, the presence of sources, and thermal parameters.

An index may require some measures of air contaminants, though comprehensive sampling for

all buildings to be indexed may prove impractical. In addition, an IAQ index could incorporate

measures of the ability of building management to maintain good IAQ conditions over time, and

thus incorporate ratings operations and maintenance protocols along with ratings of IAQ

management practices. Separate specific indices may ultimately be needed for homes, schools,

offices, and other indoor environments.

The long term goals for this program initiative are to (1) develop a generally accepted set of

indices that would reasonably represent indoor air quality in buildings, (2) provide for the quick

development of trial indices based on current knowledge, with index structures that can

accommodate easy refinement and expansion over time, (3) energize markets and other

institutional mechanisms to incorporate IAQ into decision-making based on its measurability

through such indices, and (4) establish an active area of research interest in the IAQ community

and the building community for continuous refinement of the indices.
34 U.S. EPA, 402-B-05-001, March 2005

Program Needs for Building IAQ Index Development Research:

C.1.a. Review and evaluate indexing methodologies.

Establish a panel of renowned scientists with expertise in the field of index development

in the health or environmental sciences convened under the auspices of the National

Academy of Sciences, the World Health Organization, or similar body. The panel will

review current theory and practice in the development of indices to measure

environmental conditions, and make recommendations as to (1) the criteria that should be

used as the basis for the indices (2) the methods that would be useful for constructing one

or more building indoor air quality indices, and (3) the databases that are available or

could easily be developed for use in these indices.

C.1.b. Construct and characterize different indices. 

Identify several individuals or organization, each of which will develop one or more IAQ

indices for buildings, and will characterize the indices (e.g., how does the index of IAQ

building parameters track occupant symptoms, or how does the index change as building

conditions change) using available data such as that from comprehensive building surveys

(e.g. BASE), as well as individual buildings, and hypothetical buildings designed to

evaluate the indices. 

C.1.c. Evaluate different indices and provide recommendations for selection.

Convene one or more workshops or similar forums in which the indices developed are

presented and critiqued and recommendations made for further development or selection.

Program Applications for Building IAQ Index Development Research:

With the development of IAQ indices, IAQ would become more quantifiable, enabling a host of

new program initiatives. Measurable indices would make it possible to integrate IAQ into

normal market transactions for buildings, rental space, liability insurance, health insurance, and

finance. Once institutionalized in these markets, good IAQ practices could become important in

the marketplace. Initially, the program office would promote the adoption of building IAQ

indices by appropriate national and international standard setting organizations, and then help

institutionalize these indices through cooperative programs with public and private institutions. 
U.S. EPA, 402-B-05-001, March 2005 35

C.2. DEVELOPMENT OF PUBLIC HEALTH MEASURES FOR IAQ

Background Information:

Poor or inadequate indoor air quality in the nation’s building stock may increase the prevalence

of many diseases such as lung cancer and asthma, as well as the spread of infectious diseases. 

Yet, to date, there are no mechanisms to establish the proportion of these diseases that are

directly or indirectly attributable to poor IAQ. Research is needed to establish the attributable

risk of selected health endpoints to indoor air parameters that can be measured and tracked over

time as a means to measure health gains or losses from changes in the indoor air quality of the

nation’s building stock. Such a need was recognized by the EPA’s Healthy Buildings Healthy

People (HBHP) project. 

By way of example, consider recent research that estimates the incidence of asthma, otitis media,

bronchitis, and pneumonia in children attributable environmental tobacco smoke (ETS)

exposure. The estimates are based on a review of the literature that report on the relative risk or

odds ratios of these diseases associated with ETS exposures (DiFranza and Lew, 1996), from

which attributable risk is then calculated. From information on attributable risk, the proportion of

the national incidence of each of these diseases attributable to ETS exposure has been estimated,

along with national medical expenditures for physicians, emergency care, hospitalizations, and

medications (Cunningham, Houle and Mudarri, 2002). From this information, estimates of the

reductions in the national incidence in these diseases, and the reductions in associated national

medical expenditures resulting from programs to reduce exposure of children to ETS can also be

made. Similar efforts could be initiated for other exposures, and other building conditions, and

other health endpoints. This type of data would provide a significant opportunity to establish

health-based goals under the Government Performance Results Act (GPRA), and then track

progress over time in achieving those goals.

One should harbor no illusions that a small amount of research in a short period of time will

provide comprehensive data on all the diseases attributable to indoor air that may be of interest. 

But a case can be made for providing estimates for those diseases based on existing research that

have reported relative risks or odds ratios, and then starting on a long term path to provide a

comprehensive database. The research should tie into and complement CDC's National Report(s)

on Human Exposure to Environmental Chemicals. Considering all potential health outcomes,

the long term goals of this program need for research are to: (a) develop estimates of the

incidence of all diseases attributable to poor indoor air quality; and (b) relate progress made in

improving indoor air to the improvement in public health through the quantifiable reduction in

disease incidence.
36 U.S. EPA, 402-B-05-001, March 2005

Program Needs for Research on Public Health Measures for IAQ:

C.2.a. Select target diseases and indoor air parameters.

C.2.a.1. Establish candidate diseases associated with specific indoor air quality

attributes.

Conduct a comprehensive literature review and evaluation of diseases (or other

health effects) for which national statistics are collected and for which studies are

available that provide estimates of relative risk/odds ratio, dose-response, or

similar statistical association to indoor air quality attributes. Identify candidate

diseases and attributes for further investigation. 

C.2.a.2. Identify available data and data needs to determine population exposures to

candidate indoor air quality attributes.

Conduct a comprehensive review of available data and/or data collection efforts

needed to establish the proportion of the population exposed to the indoor air

quality attributes identified in C.2.a.1.

C.2.a.3. Select two or three diseases and associated indoor air quality attributes for

development of national impact estimates.

Based on C.2.a.1 and C.2.a.2, select two or three candidate diseases and their

associated indoor air quality attributes for a concerted effort to estimate the

attributable risk and national incidence of the selected disease attributable to

indoor air quality. An important criteria for choice should be the availability of

data for appropriate estimates of attributable risk.

C.2.b. Estimate the proportion of selected diseases attributable to indoor air quality.

Data gaps on the national incidence of the selected diseases and the attributable risk

associated with indoor air quality attributes for those diseases will have to be assessed,

and, if necessary, additional studies and data collection efforts instituted. Once the data

are established, estimates of the attributable risk and the national incidence of the selected

diseases attributable to indoor air quality should be made.

C.2.c. Publish estimates of attributable risk and national incidence of selected diseases

attributable to indoor air quality.

These estimates should be thoroughly peer reviewed and published. Solicitation of

interest from a wider research community to continue these studies, selecting other

disease endpoints would be part of an overall strategy to elevate indoor air quality as a

public health concern.
U.S. EPA, 402-B-05-001, March 2005 37

Program Applications for Research on Public Health Measures for IAQ:

The health research budget in the United States is substantial, much of it is focused on research

directly related to specific diseases. Developing estimates of attributable risk to indoor air may

provide an avenue by which indoor air could be promoted as a more significant topic of interest

to the health research community. Further, these studies would allow EPA to develop

quantitative health-based GPRA goals for indoor air, establish a data collection program to track

the critical indoor air and building attributes over time, and thereby report on progress in

reducing disease incidence through improved indoor air quality.

References for Research on Public Health Measures for IAQ:

Cunningham K, Houle C, and Mudarri D. 2002. Medical Cost of Childhood Illnesses

Attributable to Environmental Tobacco Smoke: Total National Costs and Costs to Managed

Care Organizations. Draft Contractor Report prepared for the Indoor Environments Division.

U.S. Environmental Protection Agency, Washington, D.C.

DiFranza J and Lew R. 1996. Morbidity and Mortality in Children Associated with the Use of

Tobacco Products by Other People. Pediatrics. 97(4): 560-568.
38 U.S. EPA, 402-B-05-001, March 2005

D. BUILDING DESIGN AND OPERATION 

Background Information: 

Building design and operation play an important role in maintaining a healthy and productive

indoor environment. There are several factors driving building professionals to review current

products and practices, and to search for practical and effective alternatives, associated with

building design and operation. Examples of these driving forces include the green building

movement, the progression towards more energy-efficient buildings, and growing concerns over

liability due to poor indoor air quality. Other motivations include reduced costs from medical

expenses and lost work performance due to illnesses, allergies, and irritations arising from poor

indoor air quality. Although much is known or suspected regarding health risks and performance

impacts in the indoor environment, a comprehensive, integrated effort to conduct research on the

effects of building design and operation is needed.

While the potential value for improved building design and operation appears to be substantial, 

significant gaps still exist in the current state of knowledge. Building professionals are generally

unaware or lack sufficient data to know what they can do to reduce the risk of asthma, cancer,

and other serious diseases caused by indoor pollutant exposure. Best practices and products will

vary according to the diverse types, locations, and planned uses of buildings.

It is in the proper application of best practices and products that the benefits of a healthy indoor

environment that enhances human performance can be realized. The overall program goal for

research in building design and operation is to collect and develop data that can be used to create

guidelines for building professionals to use in selecting best practices and products based on

quantifiable bottom-line costs, as well as health, performance, and other related environmental

impacts (e.g., climate change, sustainable building practices, contributing to outdoor air

toxics, etc.).

Program Needs for Building Design and Operation Research:

D.1. BUILDING CHARACTERIZATION AND INTERVENTION

D.1.a. Characterize the IAQ of US building stock.

During the 1990's, the EPA conducted the Building Survey and Assessment Evaluation

(BASE) program for office buildings, which characterized the baseline levels of indoor

environmental parameters, occupant symptoms, and responses within 100 randomly

selected office buildings (Burton, Baker, Hanson et al., 2000; Girman, Baker and Burton,

2002). The BASE study results are being used by the EPA to assist with the development

of national policy related to office building design and operation. A logical continuation

would be to characterize the IAQ of other building types, such as schools, homes, and

elderly care facilities. These studies would likely be structured differently from the

BASE study, and would be more limited in scope and complexity.
U.S. EPA, 402-B-05-001, March 2005 39

This research would identify and prioritize the building types to be investigated. A major

outcome of the studies would be the correlation of occupant symptoms and responses to

building parameters including indoor and outdoor pollutant sources, outdoor air

ventilation rates, humidity control systems, and operation and maintenance practices. 

This research would also include efforts to: (1) establish panels of national experts to

develop the study protocols for each building type; (2) develop and test appropriate

sampling and measurement techniques, as needed; and (3) collect, analyze, and report on

the data. 

Pilot studies may prove to be useful in developing and refining the protocols and

measurement techniques. The data review and analysis could include further

consideration of the existing BASE data, and new data that are collected for other

building types. Data obtained from the studies of various building types should then be

combined to assess the relative contributions of these different indoor environments to

total indoor exposure. Improved exposure models could then be developed and validated. 

An example would be a study on the impacts of sources in attached garages emanating

into adjacent living spaces. 

D.1.b. Conduct intervention studies of cost, health, and performance benefits resulting

from best practices in building operation and design, and other best practices for

voluntary risk reduction activities.

This research includes conducting intervention studies to determine whether the benefits

resulting from application of building design and operation guidelines (best practices)

outweigh the cost of implementing those guidelines. The research would initially be

targeted to office buildings, schools, and residences. Given that the resources for

applying the full range of building design and operation guidelines are often limited, the

data from the field studies could be collected and reported in a manner that would assist

building professionals in deciding which specific best practices provide the highest return

on investment. Best practices for which there is the potential for significant application

costs as well as substantial quantifiable benefits include: 

- control of pollutant sources;

- moisture control;

- biocontamination prevention, clean-up and remediation;

- quantity and quality of outdoor ventilation air,

- operation, maintenance, and housekeeping practices;

- design, construction, and commissioning practices; and 

- other recommendations in EPA’s Tools for Schools kit and EPA’s Design Tools for

 Schools website

This research could also include intervention studies to determine the benefits resulting

from EPA’s indoor air quality programs, specifically actions specified to reduce risk from

indoor air toxics (e.g., the actions specified by the ETS and radon programs). 

Additionally, research is needed to determine the most effective voluntary risk reduction

methods for chemicals that are known health hazards. 
40 U.S. EPA, 402-B-05-001, March 2005

D.2. VENTILATION SYSTEMS

D.2.a. Analyze advanced ventilation system approaches.

Ventilation plays a major role in the health, comfort, and performance of building

occupants, and in the initial cost, operating costs, and liability costs of buildings. 

Research should be performed to determine the value of the following promising

ventilation technologies: 

• Vertical displacement ventilation systems: This is an approach often used in

European commercial buildings and schools to save energy and improve indoor

air quality (Seppänen, Fisk, Eto et al., 1989). The principle behind vertical

displacement ventilation is a laminar flow of low pressure air that originates at the

floor level and exhausts at the ceiling level, which ‘lifts’ pollutants away from

occupants and reduces the transport and mixing of pollutants within the occupant

breathing zone. There have been only a few demonstrations of this technology in

the U.S. (Belida, Turner, Martel et al., 1997). Research is needed to evaluate the

European and U.S. results, assess the differences between European and U.S.

applications (e.g., climatic variations, HVAC system influences, and energy

prices), and identify the most appropriate applications of this technology in

the U.S.

• Decoupled ventilation approaches: This approach involves separating the outdoor

ventilation air from the air flow that is provided for space heating and cooling. 

The potential advantages of this approach include better control of indoor

humidity, reduced capital costs, reduced energy costs and easier maintenance

(Harriman, Brundrett and Kittler, 2001). Research should focus on how this

technology could apply in different climatic regions, and how it would interface

with commonly-used HVAC system designs.

• Automation of Heating, Ventilating and Air Conditioning (HVAC) controls:

The primary purposes of HVAC controls are thermal comfort, energy-efficiency,

and regulation of outdoor ventilation air flow into the building.

Currently-available HVAC control systems often fail to perform as intended due

to improper installation, adjustment and operation. Research is needed to

prioritize equipment malfunctions and indoor contaminant levels that have the

potential to affect indoor air quality, and to determine the value that improved

controls, including new sensor technologies, would provide though

self-diagnostics and automated corrective actions.

• Residential ventilation: Traditional heating and cooling systems in U.S. homes

have not addressed the fresh air ventilation needs for home occupants. Homes

experience inadequate ventilation because they rely on infiltration and natural

ventilation with outdoor air rather than controlled mechanical ventilation systems. 

Energy-efficient home construction often results in ‘tight’ buildings with very low

leakage (infiltration). 
U.S. EPA, 402-B-05-001, March 2005 41

Over the past two decades, materials and techniques available to home builders

have resulted in typical new homes having natural ventilation rates less than what

is specified by the American Society of Heating, Refrigerating and

Air-conditioning Engineers (ASHRAE) for residences, a minimum of 0.35 air

changes per hour (Howard, 2000; FSEC, undated). The result is stale air,

moisture problems, and elevated pollutant levels indoors. 

Positive mechanical ventilation with clean outdoor air is needed to dilute indoor

contaminants. Mechanical ventilation is a relatively new practice for new home

construction, and research is needed to determine the most practical and

appropriate approaches which may, in fact, be climate-dependent. Research

should include a survey to investigate the natural ventilation rate in homes via

blower door testing; and studies intended to evaluate and improve the

cost-effectiveness of controlled mechanical ventilation so that these systems are

more-readily accepted by builders and homeowners.

Many Americans have residences in apartment buildings, with designs that range

from small buildings with a few apartments to large, multistory buildings with

hundreds of apartments units. Research is also needed to assess current

ventilation approaches for apartment buildings, and to develop recommendations

for advanced ventilation approaches that promote good indoor air quality.

• Air filter efficiency: Every type of building requires some degree of air filtration. 

Filtration is needed for several reasons, including protection of equipment,

energy-efficient operation, and protection of occupant health and performance. 

The selection of an appropriate filtration system depends on several factors

including the HVAC system design, the building design characteristics, occupancy

requirements, and financial considerations (including life cycle costs and impacts

on performance and productivity). A study is needed to determine the appropriate

filtration approach for various building types and applications for these design

parameters. 

D.2.b. Develop recommendations for improving existing building ventilation systems.

Given that the proper quantity and quality of ventilation is a critical component of good

IAQ, utilize a literature survey, field surveys, and field studies to identify the typical

failure modes and operating problems for ventilation systems. Typical failure modes

result from design and construction errors (such as selection of noisy equipment that is

turned off by occupants, variable-air-volume (VAV) systems with fixed outdoor air

dampers and/or no minimum settings to ensure adequate ventilation at reduced load);

operation and maintenance errors (such as neglect, turning off ventilation systems due to

noise or comfort, not performing a periodic check to measure the outdoor air flow rate);

and simple deterioration of equipment. Based on this data, develop maintenance and

operation procedures, and practical upgrades for existing ventilation systems, to help

ensure a proper supply of outdoor air in existing buildings; and to stimulate the
42 U.S. EPA, 402-B-05-001, March 2005

production of better ventilation equipment. Examples of potential research areas include

optimizing the performance of unit ventilators in existing school classrooms, assessing

and recommending ventilation approaches for multi-family (apartment) dwellings, and

developing ventilation recommendations for urban areas with potentially large sources of

outdoor pollution.

D.2.c. Characterize the impact of ventilation systems and occupant density on the rate of

transmission of infectious diseases in indoor environments.

There is suggestive evidence that low outdoor air ventilation rates and high occupant

density increase the transmission of common respiratory diseases such as the common

cold and the flu virus (Wheeler, 1997). However, it is not clear the extent to which this

occurs, and the extent to which increased ventilation rates mitigate the impacts of

occupant density. In addition, vertical displacement ventilation systems may serve to

reduce disease transmission from infected individuals by virtue of the air flow patterns

that are established. Since respiratory disease impacts have a significant public health

implication, and since sick absences are a significant cost factor to the economy,

quantitative data on the impacts would go a long way to resolving the controversy

surrounding the rate of ventilation that is considered adequate, and for identifying

superior ventilation designs. Initial studies should be performed for high-occupant

density environments, such as classrooms or auditoriums, to determine if there is a

measurable effect and whether further investigations are warranted.

D.3. CONTROL OF RADON AND OTHER SOIL GASES

D.3.a. Conduct studies on potential humidity control benefits of radon mitigation systems.

The most commonly used approach for reducing radon levels in residential applications

involves active soil depressurization (ASD). Radon mitigation systems based on this

approach typically use one or more vent pipes with a fan to remove soil gases from

beneath a home’s foundation and vent the soil gases to a location away from the home’s

living space (U.S. EPA, 1993; ASTM, 2001). It is estimated that approximately 500,000

homes in the United States have had elevated radon levels reduced using ASD radon

mitigation systems over the last 15 years (Jalbert and Gregory, 2002). There have been

anecdotal reports that homeowners often perceive additional improvements in the IAQ in

their homes after an ASD radon mitigation system has been installed. Common

perceptions are that the home feels drier, there are fewer problems related to high indoor

humidity, and musty odors in basements are reduced. Research is needed to investigate

whether ASD radon mitigation provides additional IAQ benefits, particularly with respect

to reducing indoor moisture and humidity problems, and which also could result in

reduced indoor mold and mildew. Pending the results for ASD radon mitigation systems,

follow-on investigations may be appropriate for passive radon control systems (passive

systems do not incorporate a fan) that are commonly used in new home construction. 

Information to support this research need may be provided by ongoing programs such as

that described in section D.3.c. for evaluating methods to control migration of volatile

contaminants in soil gases into the indoor environment. Research should also investigate
U.S. EPA, 402-B-05-001, March 2005 43

the effectiveness of radon mitigation systems over time (in reducing radon levels and

potentially providing humidity control benefits).

D.3.b. Conduct studies to evaluate radon-resistant construction techniques for new homes.

Radon-resistant new construction (RRNC) techniques reduce indoor concentrations of

radon by blocking radon entry points through the use of sealing techniques, and by using

the natural upward thermal draft in a passive vent pipe to slightly depressurize the area

under the home’s foundation (U.S. EPA, 1994). The passive vent pipe is typically run

through the conditioned portion of the home (usually hidden in an interior wall or pipe

chase), and relies on the natural upward draft of gases in the pipe caused by the difference

between indoor and outdoor temperatures. Research is needed in the following areas to

support the EPA’s Radon Program:

• Effectiveness of RRNC for reducing radon levels: Research conducted to date

shows that RRNC techniques typically reduce radon levels by approximately 50%,

on average, however there is a range in the reported results (NAHB Research

Center, 1994; NAHB Research Center, 1996; LaFollette and Dickey, 2001). 

More research is needed to further investigate the effectiveness of RRNC

techniques, which includes assessing the effect of builder installation techniques

and quality control, and the effects of seasonal weather variations. Research

should also investigate the effectiveness of RRNC over time. Research could also

investigate the potential energy benefits and the Integrated Pest Management

(IPM) benefits that may result from the improved home sealing associated with

RRNC.

• Installation costs of RRNC: An often significant barrier towards getting builders

to incorporate RRNC techniques into new homes is the incremental added cost for

the features. Some studies were conducted in the early 1990s (ICF, Inc. &

Camroden Associates, Inc., 1992), however research is needed to assess the

current RRNC installation costs experienced by home builders. The research

should consider situations where some of RRNC techniques are already

implemented as part of the normal home building process (e.g., gravel layer,

polyethylene sheeting, weatherization). The research should also investigate the

additional costs associated with activating passive RRNC systems, which is

accomplished by installing a fan and system operating indicator.

D.3.c. Conduct studies to evaluate methods to control migration of volatile contaminants in

soil gases.

Another source of toxic contaminants indoors relates to contaminated soil gas resulting

from contaminated ground water, leaking storage tanks, toxic dumps, and landfills. 

There are tens of thousands of Superfund and RCRA sites that are known and probably

many that are still unknown. Volatile contaminants in soil gas can enter buildings in a

manner similar to radon. Consequently, mitigation methods similar to those effective

with radon may be used. However, current health-based risk reductions often requires
44 U.S. EPA, 402-B-05-001, March 2005

much higher performance of the mitigation methods (such as sub-surface

depressurization) than is required by the corresponding radon action level. Additional

research and development may be required to optimize the performance of these systems.

The government currently has an emphasis on the development of Brownfields, many of

which have contaminated ground water and vadose zones. Buildings constructed over

these areas will be prone to indoor air toxic problems. This is a circumstance in which

the methods for radon reduction in new construction should be revisited to ascertain their

applicability to control these new soil gas contaminants. While many of the construction

methods will be directly applicable to other toxic soil gases, some research issues exist. 

First of all, the required level of protection may be significantly higher than in the

corresponding case for radon. Consequently, the level of performance of the proposed

construction methods must be tested and demonstrated to provide adequate protection by

reducing the risk levels appropriately.

There may be some implications for both active (fan-driven) and passive (natural draft)

mitigation strategies for the toxic gases associated with volatile contaminants in the soil

and groundwater. These gases may diffuse through concrete slabs more effectively than

radon. Consequently, prevention of advective transport into buildings may not result in

sufficient protection of the indoor environment. In the case of radon, it was observed that

reversing the direction of air flow through the building foundation from inward to

outward almost always reduced the indoor radon concentrations below the action level. 

This appeared to be true even when the sub-slab concentration of radon was only

nominally reduced. This result agreed with measurements of diffusion rates through

concrete slabs. If the effective diffusion rates through the slab are significantly higher for

these other gaseous contaminants, then there may be potential for elevated indoor

contaminant levels even when a negative pressure is maintained beneath the slab. 

Effective mitigation methods may be required, not only to reverse the direction of

advective flow through the building foundation, but also to reduce the sub-slab

concentration to quite low values. Some new research and development work may be

required to extend the capabilities of current radon reduction methods to be effective

against these new soil gas contaminants. Research should also investigate the

effectiveness of these systems over time (in reducing radon levels and indoor

concentrations of volatile contaminants from the soil and ground water). Research could

also investigate the potential impacts of contractor qualifications and installation

techniques on the effectiveness and durability of these systems.

D.3.c.1. Conduct studies to investigate relationships between subsurface

concentrations and indoor concentrations of volatile contaminants.

A vapor intrusion-focused research topic that has recently been initiated by the

EPA’s Office of Solid Waste & Emergency Response (OSWER) and Office of

Research & Development (ORD) involves efforts to collect evidence from

investigations of vapor intrusion cases from across the United States for

incorporation into the Indoor Air Vapor Intrusion (IAVI) database. This research

effort is initially focusing on defensible evidence of the relationship between the
U.S. EPA, 402-B-05-001, March 2005 45

subsurface concentrations and the associated indoor air concentrations

(i.e., amount of attenuation in vapor concentrations), see: http://iavi.rti.org. 

Anticipated future efforts include working to identify the site-specific

characteristics that influence the observed attenuation factors. This information

could be used to help improve the accuracy of predictions and prevent the overand/or under-regulation of these exposures.

D.4. BUILDING DESIGN AND IMPLEMENTATION

D.4.a. Conduct research to support building materials selection and installation

procedures.

D.4.a.1. Compare and evaluate product emission methods and standards.

As part of the green building movement, a number of organizations have

established mechanisms for evaluating or rating products with respect to their

impact on indoor pollution and health. For example, Green Seal, a non-profit

institution, provides product standards based on product formulations, while

Green Guard, another non-profit organization uses an emission measurement

method along with a set of health criteria. As the Green Building movement is

rapidly expanding, and includes the encouragement and support of EPA, a host of

institutions are using these or similar standards. However, there is a growing

concern that many of these standards are not protective of health and may have

little scientific foundation. The State of California has developed emission-based

standards using California’s acute and chronic exposure levels as it’s health basis

and appears to be the most scientifically supportable, but it has not received

independent scrutiny or wide public acceptance. EPA is developing green

building guidance for federal facilities but has yet to address the indoor pollution

issues involved in the selection of products. Research is needed to provide a

systematic comparison and evaluation of the major methodologies and standards

used for evaluating products based on the extent to which they limit indoor air

pollution and protect public health. Such research would inform the green

building community and guide EPA as it develops and refines its guidelines.

D.4.a.2. Develop a building materials selection and installation protocol.

The materials, finishes, furnishings, maintenance supplies, and housekeeping

supplies that go into new or existing buildings can have a major impact of the

quality of the indoor air. Building professionals responsible for the materials

acquisition are becoming more aware that proper selection is important to the

health and performance of occupants. Comprehensive yet easy to follow

guidelines on how to best select products are urgently needed, yet the

development of such guidelines is not possible without emissions and health

effects data on key building sources and products. Research should identify the

sources and products with the greatest impact on IAQ, and characterize their

emissions and health effects. This research interrelates with the Chemicals and
46 U.S. EPA, 402-B-05-001, March 2005

Sources program needs in this document, which describe developing quantitative

emissions factors for various sources (section A.1.d.2).

With this information, a set of quick and easy materials selection guidelines,

providing objective criteria to building designers, could be developed. Criteria

could then be developed for determining what constitutes ‘best’ materials,

including effects on occupant health and performance (as information is

available), initial capital costs, operating costs, materials performance, life-cycle

costs, outdoor environmental impacts, and other impacts on indoor quality

through activities such as materials maintenance and replacement.

In addition to materials selection, it is also important to determine appropriate

recommendations for installation, for example, scheduling sequence and minimal

use of problematic emitting materials.

D.4.b. Conduct studies on the relationship between IAQ, energy efficiency, and moisture

management.

Current market trends include designing and constructing energy-efficient buildings,

which often results in practices that can adversely affect the quality of the indoor

environment. Energy-efficiency and IAQ are strongly interdependent. Proper

implementation of energy-efficiency measures requires a thorough consideration of IAQ

impacts. Similarly, IAQ measures must be implemented in a manner that is consistent

with energy-efficiency goals. For example, there is often a perceived conflict between

ventilating with an adequate quantity of outdoor air and the need to minimize energy

costs. Research is needed to investigate energy-efficient heating, cooling and ventilation

techniques which promote good IAQ. 

Energy-efficient buildings can have IAQ problems when moisture management is not

properly addressed during the design and construction. Moisture management is often a

climate-specific issue. Improperly designed and constructed buildings and mechanical

systems can cause indoor moisture problems due to air-flow-induced moisture transfer

through the building shell, condensation, outdoor air ventilation, and improper surface

water drainage. Research is needed to develop design guidelines that will minimize the

potential for mold and comfort problems resulting from excessive indoor moisture.

D.4.c. Evaluate current and popular building practices.

Several practices in building design and operation can have a substantial impact on

indoor air quality, thus affecting health and performance. Many of these practices result

from current trends in ‘green building’ and sustainable development. Following are

examples of building practices that should be evaluated for indoor air quality, economic,

and performance impacts:
U.S. EPA, 402-B-05-001, March 2005 47

• Use of recycled content materials in new and existing buildings; 

• Siting new buildings on brownfields, landfills, and other contaminated sites

(e.g., evaluating soil gas intrusion and its contribution to indoor contaminant

levels, and evaluating the effectiveness of mitigation techniques such as sub-slab

depressurization);

• Siting new buildings in areas with high moisture load potentials, such as filled-in

wetlands and flood zones;

• Use of air purification such as germicidal ultraviolet lights, carbon air filters, and

ion and ozone generators (see also sections F.1 and F.2); 

• Use of biocides in building materials, maintenance supplies, and air filters

(see also section F.1);

• Duct cleaning (determining whether it is needed, what methods are most effective,

and the relative value of duct cleaning versus air handling unit cleaning);

• Floor type and materials selection; 

• Floor care focused on particle control via high-efficiency vacuums, central

vacuums, entry mats, floor maintenance materials and procedures; 

• Sloped roofs as an alternative to the flat roof systems that are typically used in

non-residential buildings, to provide better moisture management;

• Attached garages (e.g., evaluating contaminant levels and exposures in adjacent

occupied spaces, assessing building design impacts and mitigation strategies);

• Building and HVAC system commissioning and periodic re-commissioning 

(commissioning is a formal process intended to verify and document that a

building and/or HVAC system is constructed, adjusted, and performing in a

manner consistent with its intended design);

• Building flush out to remove built-up contaminants prior to occupancy.

Program Applications for Building Design and Operation Research:

Historically, risk evaluations of environmental exposures have focused on long term exposures

leading to chronic diseases such as cancer. Exposures are often modeled based on limited field

data. With the development of the Building Assessment Survey and Evaluation Study (BASE),

the EPA is making data available, specific for commercial office buildings, for rigorous

assessments of both chronic and short term exposures and risks. With BASE data, researchers are

now beginning to examine exposures leading to other health endpoints such as respiratory

diseases, as well as health symptoms such as headache and mucous membrane irritation. 

Examination of the building conditions and practices that lead to these health effects can also be

examined. The proposed research for the development of similar data on other building types,

using compatible data collection protocols, would lead to a broad set of analyses to identify the

full impact of indoor air on health, comfort, and productivity of occupants; the attributable risk

associated with specific building contaminants, sources, and practices; and the mitigation steps

required to minimize risk. 

New ventilation technologies and systems, such as displacement ventilation, decoupled

ventilation, as well as energy recovery ventilation systems have the potential to greatly improve

indoor air quality at significantly reduced energy costs. In addition, new controls and automation
48 U.S. EPA, 402-B-05-001, March 2005

systems stand to greatly improve system efficiencies. The proposed research is designed to

accelerate the demonstration and adoption of these technologies.

In addition, the EPA has provided the most comprehensive and up to date IAQ guidance for

commercial buildings, schools, and radon in residences. However, while the guidance is

comprehensive, it is generic, and not necessarily tailored to the actual building stock. The next

steps in the evolution of this guidance await further research. The proposed research would

evaluate the effectiveness of mitigation practices that are recommended, identify and assess the

most common failures of building systems and controls that lead to indoor air quality risks, and

evaluate new technologies and products that could improve or degrade progress toward improved

indoor environments. 

Further, the proposed research is designed to provide information needed to guide ever-growing

constituencies for indoor air, such as those constituencies dealing with energy efficiency, green

building design and construction, and homeland security.

References for Building Design and Operation Research:

ASTM. 2001. ASTM E-2121, Standard Practice for Installing Radon Mitigation Systems in

Existing Low-Rise Residential Buildings. West Conshohocken PA: American Society for

Testing and Materials.

Belida, LM, Turner WA, Martel SM, et al. 1997. The Advantage Classroom; Sustainable

Design For Achieving Indoor Air Quality, Comfort, and an Improved Learning Environment,

Proceedings of the Healthy Buildings/IAQ ’97 Conference - Global Issues and Regional

Solutions, Vol 1, pp 123-128. Washington DC: Healthy Buildings/IAQ ‘97.

Burton LE, Baker BJ, Hanson D, et al. 2000. Baseline Information on 100 Randomly Selected

Office Buildings in the United States (BASE): Gross Building Characteristics, Proceedings

of Healthy Buildings 2000, Vol 1, pp 151-155. Helsinki: Healthy Buildings 2000.

FSEC, undated. Priorities for Building a New Florida Home. Florida Solar Energy Center Web

Site: www.fsec.ucf.edu/Bldg/FYH/PRIORITY/Index.htm.

Girman JR, Baker BJ, and Burton LE. 2002. Prevalence of Potential Sources of Indoor Air

Pollution in U.S. Office Buildings, Proceedings of the 9th International Conference on Indoor

Air Quality and Climate - Indoor Air 2002, Vol 4, pp 438-443. Santa Cruz: Indoor Air 2002.

Harriman LG, Brundrett GW, and Kittler R. 2001. Humidity Control Design Guide For

Commercial and Institutional Buildings. Atlanta: American Society of Heating,

Refrigerating, and Air Conditioning Engineers, Inc. 

Howard B, 2000. Accounting for Air Infiltration. Home Energy Magazine Online

November/December 2000. Web site: http://hem.dis.anl.gov/eehem/00/001103.html.
U.S. EPA, 402-B-05-001, March 2005 49

ICF, Inc. and Camroden Associates, Inc. 1992. Analysis of Options for EPA’s Model Standards

for Controlling Radon in New Homes. Draft Contractor Report prepared for the EPA Radon

Division. U.S. Environmental Protection Agency, Washington, D.C.

Jalbert P and Gregory B. 2002. National Radon Results: 1985 to 2003. Published on EPA web

site: www.epa.gov/radon/pdfs/natl_radon_results_update.pdf

LaFollette S and Dickey T. 2001. Demonstrating Effectiveness of Passive Radon-Resistant New

Construction. Journal of the Air & Waste Management Association. Volume 51:102-108. 

January 2001.

NAHB Research Center. 1994. The New Home Evaluation Program. Final report provided for

EPA Grant No. X819586-01-0. Upper Marlboro MD: NAHB Research Center.

NAHB Research Center. 1996. Seasonal Performance of Passive Radon-Resistant Features in

New Single-Family Homes. Final report provided for EPA Grant No. X 819586-01-5,

Task 2. Upper Marlboro MD: NAHB Research Center.

Seppänen OA, Fisk WJ, Eto J, et al. 1989. Comparison of Conventional Mixing and

Displacement Air-Conditioning and Ventilating Systems in U.S. Commercial Buildings. 

ASHRAE Transactions. V. 95, Pt 2. VA-89-19-3.

U.S. Environmental Protection Agency (U.S. EPA). 1993. Radon Mitigation Standards. Office

of Air and Radiation. EPA 402-R-93-078. Revised edition republished in April 1994.

U.S. Environmental Protection Agency (U.S. EPA). 1994. Model Standards and Techniques for

Control of Radon in New Residential Buildings. Office of Air and Radiation. 

EPA 402-R-94-009.

Wheeler AE. 1997. The V in Classroom HVAC. ASHRAE Journal. October 1997, pp 48-55.
50 U.S. EPA, 402-B-05-001, March 2005

E. HOMELAND SECURITY

Background Information:

Recent events and the increased threat of terrorist activities in the U.S. have heightened the need

for measures to prevent and clean-up potential releases of chemical, biological, and radiological

warfare agents into buildings. There are also instances when remedial measures are needed to

address accidental and unintentional releases of toxic substances and other potentially hazardous

conditions within the indoor environment. This section presents a simple overview of potential

research initiatives in these program areas, which are rapidly emerging. The EPA will likely be

receiving major funding increases in FY03 and outyears for research initiatives related to

homeland security, planned for execution within several offices including the Office of Research

& Development (ORD); the Office of Solid Waste & Emergency Response (OSWER); the Office

of Water (OW); the Office of Prevention, Pesticides and Toxics (OPPT); and the Office of Air

and Radiation (OAR). 

Because this is a rapidly emerging area, the present version of PNIER does not attempt to capture

all of the detailed indoor environments research initiatives that can and should be pursued by the

EPA for homeland security. The broad research initiatives identified in this section of PNIER

will be further developed, shaped and refined as the larger EPA initiatives and programs become

established. In September 2002, the EPA published a high-level strategy for homeland security

(U.S. EPA, 2002), and efforts will be made to ensure that the indoor environments research

needs contained in PNIER are consistent with that strategy. The EPA’s Office of Research &

Development has established a National Homeland Security Research Center (NHSRC), and a

Safe Buildings research program for addressing detection/sampling and analysis; containment;

decontamination; and disposal. All homeland security research outlined in this document will be

closely coordinated across these Agency programs. 

There are several chemical agents (e.g., nerve agents, blister agents, choking agents) and

biological agents (e.g., anthrax, botulinum toxin, ebola, ricin, etc.) which could be employed

under terrorist or wartime activities because of their direct toxic effects. Although there are

several thousand poisonous agents known, only a limited number are generally considered

suitable for warfare due to their nature and ability for storage and resistance to climate. 

While some treatments and antidotes are known for a portion of these agents, there is a great deal

of research that needs to be done. However, due to the varied nature of the agents and the

multitude of ways to expose a population (i.e., in the water supply, as a plume in the outside air,

through the ventilation system in a building, or as a direct contaminant release inside a building), 

it is not reasonable to expect that the most effective immediate reaction to these threats will or

should be medical in nature. Therefore, it is important to establish ways to limit the ability of

these agents to reach the population at large, particularly in the indoor environment. 

Any products or technologies developed for homeland security should be objectively evaluated,

with thorough performance verification.
U.S. EPA, 402-B-05-001, March 2005 51

Program Needs for Homeland Security Research:

E.1. Conduct simulation modeling studies of contaminant releases to determine critical

pathways and control variables.

Releases of chemical, biological, and radiological agents should be simulated under a

variety of conditions and assumptions of survival potential, using available building air

flow models (research may reveal that modifications are needed for existing models). 

Studies are needed to characterize the fate and transport of chemical, biological, and

radiological agents in indoor environments under a variety of conditions, including: 

outdoor releases, indoor releases, and point sources which could include individuals. 

The information obtained during this research will serve as a foundation for prevention,

mitigation and clean-up guidelines for the indoor environment.

E.2. Conduct research to support the development of EPA guidance to ensure emergency

preparedness in building types through operation and maintenance practices.

In its role as the lead government agency for building emergency preparedness, the EPA

needs to develop credible and practical guidance for building owners and operators to

ensure adequate protection in the event of a chemical, biological or radiological

contamination incident. Research is needed to develop, demonstrate, and verify building

operation and maintenance practices which help prevent indoor air contamination, and

ensure suitable building emergency preparedness. This should include development of

building ventilation system operation and maintenance recommendations, considering

both outdoor and indoor sources of the contaminants, and identifying the key variables

that can be controlled to prevent and mitigate contaminant transmission. Once developed,

these recommendations could be added to existing educational and support materials

used by building operators (e.g., maintenance and operation checklists).

E.3. Conduct research to support the development of EPA guidance to ensure emergency

preparedness in building types through new technologies and materials.

Research is needed to identify and develop suitable detection methods for chemical,

biological, and radiological contaminants. Special considerations should be given to the

development of practical sensor and control system technologies that will allow

immediate identification and automated building response to a potential threat. Other

technologies that warrant research include improved air filtration and cleaning system

designs, and alternative air distribution system designs. New technologies and materials

must have the capability to be applied cost-effectively to a broad range of contaminants

and building types.

E.4. Conduct research to support building clean-up and re-occupancy.

After emergency response, the issue of clean-up after a chemical, biological, or

radiological warfare incident or an accidental toxic release is a matter of continued

concern. There is insufficient information available to support the use of existing
52 U.S. EPA, 402-B-05-001, March 2005

building clean-up protocols with a high degree of confidence. Highly-controlled

laboratory studies should be conducted to establish with confidence appropriate cleaning

agents and processes to ensure that clean-up is successful, and that workers are

sufficiently protected. Information from these studies will be used to establish guidelines

for EPA and other public health entities engaged in clean-up efforts. Specific research

areas include:

• reviewing currently available threat analyses (including NHSRC’s efforts)

• developing lists of contaminants of concern (e.g., from terrorism, criminal activities, or

accidental incidents),

• conducting baseline contamination and decontamination studies,

• developing standards for appropriate levels of clean-up, which could be dependent on

the specific contaminant(s) and other building-related factors. This would be closely

coordinated with NHSRC’s Rapid Risk Assessment Program.

E.5. Verify the performance of products and technologies developed to address

homeland security.

Verification is needed to validate claims for products and technologies that have been and

are being developed to address homeland security concerns. For example, in response to

recent terrorist incidents there is an increasing number of products being developed and

marketed to address issues such as biological warfare (e.g., the release of anthrax from

intentionally contaminated mail in office buildings), and exposure and clean-up after

terrorist incidents. The protection of the American citizens is of utmost concern, and

there needs to be objective research performed to ensure that only safe, credible and

reliable products are introduced into the public marketplace. These research efforts will

be closely coordinated with the NHSRC’s Environmental Technology Verification (ETV)

efforts.

An example would be to investigate the effectiveness of sheltering-in-place actions for

schools, office buildings, and other public facilities. This has already been demonstrated

for residential applications under the Chemical Stockpile Emergency Preparedness

Program (Sorensen and Vogt, 2001).

Program Applications for Homeland Security Research:

The vulnerability of building occupants to a chemical or biological attack depends on the

location of the release, characteristics of a building that affect air flow patterns, the location of

occupants, and the preparedness of the building management to recognize an attack, and to

subsequently be able to isolate and contain the contaminants. The proposed research would

provide the basis for the EPA to develop guidelines for building and governmental officials to

prepare for and react appropriately to an attack. In addition, further proposed research is needed

to prepare for effective clean up of the attack agents and other related contaminants after the

attack, so that buildings can be re-occupied.
U.S. EPA, 402-B-05-001, March 2005 53

References for Homeland Security Research:

Sorensen J and Vogt B. 2001. Will Duct Tape and Plastic Really Work? Issues Related to

Expedient Shelter-In-Place. Oak Ridge National Laboratory Report ONRL/TM-2001/154. 

Date published - August 2001. 

U.S. Environmental Protection Agency (U.S. EPA). 2002. Strategic Plan for Homeland Security. 

September 2002. Published on EPA web site:

www.epa.gov/epahome/downloads/epa_homeland_security_strategic_plan.pdf
54 U.S. EPA, 402-B-05-001, March 2005

F. PRODUCT AND TECHNOLOGY VERIFICATION

Background Information:

There are several products and technologies available in the public and commercial marketplaces

that are promoted for their contribution to a healthy indoor environment. In many cases, the

effectiveness and net health impacts of these products and technologies have not been fully

evaluated. The research needs described in this section are intended to address some of these

information gaps, however it is expected that the scope of the research will likely exceed what is

captured in this document as new products and technologies evolve. 

Program Needs for Product and Technology Verification Research:

F.1. Conduct research on source control products and technologies.

Often the most effective approach to reducing indoor air contaminant exposure is source

control. Source control involves both removal and control of contaminant levels.

There are several products and appliances marketed for use on surfaces and in ventilation

systems (e.g., anti-microbial cleaners and sealants, air fresheners, vacuum cleaners, etc.)

which are marketed for this purpose. Many of these products have not been fully

assessed for their net effectiveness in improving indoor air quality, and some of these

products can themselves be sources of indoor air pollution. In addition, the impact on

human health especially from inhalation exposure to these products or by-products

produced during use of some of these products has not been fully investigated. One major

concern from a health standpoint is the increased incorporation of anti-microbial agents

and fragrances in some of these products. There are also concerns expressed in literature

about the potential impact of high-level use of these products on human immune system

development and biological organism resistance as well as the unknown potential for

health impacts from long-term, low-level exposures, which have not been investigated. 

Further research is needed on each of these issues and data gaps. 

F.2. Investigate the performance of air treatment systems.

The performance of air cleaning systems (e.g., ionizers, electrostatic precipitators,

ultraviolet germicidal lights, photocatalytic cleaners, activated carbon filters, and alumina

coated filters), and filter efficiencies need to be investigated to compare the results with

vendor claims. These devices are widely advertised as effective methods for cleaning up

the air and providing symptomatic relief for individuals with indoor air health and

comfort concerns. However, air cleaning devices and air filters are not generally

sufficient by themselves to reduce indoor air contaminant exposures especially when

there are large pollutant sources, or the pollutants themselves settle-out on surfaces. 

In general, the health benefits of air filters and air cleaning devices are not objectively

clear and most claims are based on the very limited scientific evidence. In addition, there

are several questions about the potential for adverse impacts on respiratory tissues and

chronic or latent health effects due to contaminants (e.g., ozone, hydroxyl radicals and

other oxidizing agents, ionized particles, formaldehyde, etc.) emitted by some air cleaning
U.S. EPA, 402-B-05-001, March 2005 55

devices that have not been thoroughly investigated. As part of this work there is a need to

assess and input into the test standards presently used by the industry for various

categories of equipment.

F.3. Investigate risk management controls for indoor fuel-fired heating and cooking

devices.

Billions of people around the world are exposed to high levels of combustion byproducts

from indoor use of propane, methane, kerosene, natural gas, traditional biomass

(e.g., wood, dung, and crop residues), and other fuels during heating and cooking.

The specific pollutants of concern and the potential health risks from these indoor

exposures are dependent on several factors including fuel types, appliance designs,

building factors (i.e., ventilation levels, building design, room dimensions, etc.), use

patterns, and individual susceptibilities and vulnerabilities with potentially greater impact

on highly vulnerable populations such as the elderly, women, children, the chronically ill,

and the economically disadvantaged. In addition, the choice of appliance and fuel-type is

often associated with societal and cultural issues or beliefs. Biomass burning is

associated with 1.6 million deaths per year, adverse pregnancy outcomes, and increased

risk of serious respiratory infections worldwide (WHO 2002).

In the United States and several other industrialized countries, there is a body of literature

and research on the performance of indoor fuel-fired heating and cooking devices,

potential levels of indoor contaminants resulting from these devices, potential health

impacts of these contaminants at higher levels, and performance certification programs

for some appliances and fuel types. A large portion of the global population is exposed to

high levels of contaminants from a wide variety of device designs, particularly in

non-industrialized nations. There are also several unknowns related to the specific health

impacts of exposure to lower levels of contaminants and exposures experienced by

certain susceptible populations, use patterns, and risk reducing technology modifications

that need to be addressed (see also A.1.b and A.1.h.2). Several studies in developing

countries have documents the health impacts of burning traditional biomass and coal fuels

indoors for home cooking and heating. Assistance is needed with evaluating risk control

options that are being employed and building local/regional capacity for monitoring

indoor air pollution in homes with improved technologies.

 

Research is needed to investigate and develop self-sustaining and viable risk control and

risk management options. Research should consider social, cultural, and economic

barriers related to the use of fuel-fired heating and cooking devices and fuel choices in a

variety of industrialized and non-industrialized settings. These investigations should

include consideration of new risk reduction technologies and development of design

guidance or standards. Specifically, research is needed to investigate the performance of

improved cook stoves, as more information is needed on the emissions, efficiency and

reliability of improved technologies and fuels that are being developed and promoted. 

Research is also needed to investigate the performance of new personal monitoring

devices that have been developed to measure PM and CO, and to develop and establish

recommended sampling methods for these devices.
56 U.S. EPA, 402-B-05-001, March 2005

Program Applications for Product and Technology Verification Research:

As good indoor air quality becomes more widely appreciated and desired by consumers, a host of

products are being increasingly developed and marketed to solve or protect against indoor air

quality problems. These products include new air cleaning technologies, anti-microbial agents,

air fresheners, and air quality sensors. With this increased presence in the marketplace there

have been increased inquiries concerning the efficacy, effectiveness, and benefits of these

products. However, whether many of these products work, how they work, and what possible

secondary contaminants or health effects may be created or enhanced from use of some of these

products is often unknown and is of utmost concern to the indoor air quality community. 

The research proposed in this section addresses the need for further evaluation of the

performance, effectiveness, and potential positive and/or negative impacts on indoor air quality

and human health from these types of products. This information will help EPA and other

concerned federal, state and local organizations to subsequently issue information reports and

guidelines to potential users.

References for Product and Technology Verification Research:

World Health Organization (WHO). 2002. Reducing Risks, Promoting Healthy Life. Geneva,

Switzerland: World Health Organization.