United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
it.
Research and Development
EPA-600/S2-84-099 July 1984
SER& Project Summary
Review of Recent Research in
Indoor Air Quality
E. R. Kashdan, J. E. Sickles, and M. B. Ranade
This report reviews indoor air quality
research in an effort to define the state-
of-the-art.
Several approaches were taken.
About 150 recent journal articles,
symposium presentations, and bibli-
ographic reports were reviewed and
are presented in an annotated
bibliography, arranged by subject. In
addition, about 30 prominent
researchers in indoor air quality were
contacted, these contacts are
summarized. Significant articles (prior
to 1980) were also reviewed; these are
listed in a separate unannotated bibli-
ography. Two tables summarize the
information in the annotated bibliog-
raphy and contact summaries.
The report also briefly discusses the
quality and apparent deficiencies of the
reviewed data base of articles, reports,
and books.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory. Research Triangle
Park. NC. to announce key findings of
the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Indoor air quality is recognized as a
significant factor affecting the well-being
of the average American. In recent years,
energy conservation (e.g., weatherizing
buildings and the greater use of unvented
combustion (heattng) devices) has
apparently increased indoor concentra-
tions of hazardous air pollutants. Thus
the identification and evaluation of
sources of indoor air pollution and their
control has received increasing attention
from Federal and State agencies
concerned with health and environment-
al protection.
The objective of this report is to
establish the state-of-the-art in indoor air
quality research by contacting prominent
researchers in the field, summarizing
their efforts and capabilities, and
reviewing published articles and reports
The report is intended to assist the indoor
air quality research community in
assessing the content and quality of its
recent research efforts, to highlight
milestone indoor air quality studies or
symposia, and to identify research
facilities available to the user community.
This information should enhance
coordination of government and private
research efforts.
Procedure
The attempt to define the state-of-the-
art in indoor air pollution research involve
a review of recent literature, and
telephone contacts with prominent
investigators. The literature review
includes searches of computer files,
citation lists in several compendiums,
and review articles. Manual searches of
journals that frequently publish indoor air
quality research provided articles current
through December 1983. Primary
emphasis was on peer-reviewed journal
articles, rather than government reports
or symposium presentations. Personnel
at about 30 prominent investigating
laboratories were contacted to assess the
extent of ongoing research in indoor air
quality. Specific inquiries into the nature
of the work, measurements performed,
funding levels, sponsor, and special
facilities provided an up-to-date
inventory. The report includes an
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annotated bibliography and summaries of
contacts with investigators.
Results and Discussions
The principal result of the literature
review was an annotated bibliography,
arranged by subject. Most citations in the
bibliography are from peer-reviewed
journal articles, dated between 1980 and
1983. Presentations from a few, very
recent symposia are also included to
provide the most current work.
Government reports other than
annotated bibliographies, literature
reviews, or general treatises -- are not
included. Some pre-1980 articles were
included because their subject matter
seemed unique or they represented
significant work that was frequently cited
thereafter.
As shown in the Table 1 outline, the
bibliography is organized under five
major headings: I. Characterization and
Measurement, II. Control Methods, III.
Health Studies, IV. Modeling, and V.
General Reviews. Areas I, II, and IV were
of prime concern for this project, and,
consequently, are further divided into
topics. Many articles, of course, span
several subject areas; where this occurs,
the work was classified according to the
primary objective of the research.
The annotated bibliography is by no
means complete. Nevertheless, several
observations may be made about these
studies and perhaps generalized to indoor
air quality research. "Characterization
and Measurement" (Area I) has certainly
received the most attention. Researchers
have expended much effort to sample
various premises for levels of certain
pollutants. In some studies, an identified
pollutant source (e.g., a gas-fired range)
is present; in others, many premises are
sampled to determine an average
exposure level; or an attempt is made to
relate indoor to outdoor pollutant levels.
Many studies seem to reflect the
perception that indoor air quality is
determined largely by outdoor air quality.
Two significant changes in the habits of
building occupants challenge this
perception: (1) the reduction of air infiltra-
tion rates to conserve energy has further
insulated indoor from outdoor air, and (2)
the popularity of unvented combustion
sources for space heating suggests that
indoor pollutant sources may be far
greater than outdoor sources. However,
few studies have attempted to determine
emission rates from these unvented
combustion sources.
In "Control Methods" (Area II) most
studies have measured the effect of
ventilation rates on indoor air quality.
Table 1. Outline of Annotated Bibliog-
raphy
I. Characterization and Measurement
A. Aerosols
1. Indoor aerosols
2. Tobacco smoke
3. Asbestos
4. Fibrous glass and mineral
wool
5. Viable aerosols
B. Indoor/Outdoor Relationships
1. Fixed site
2 Exposure monitoring
C Gaseous Pollutants
1. Inorganics (also CO, COn>
2. Organics (not CO, COgf
D. Radon
E. Consumer Products
F. Combustion Sources
G. Odor
II. Control Methods
A. Air Purifying Methods
B. Ventilation
C. Source Modification
D. Miscellaneous
III Health Studies
IV Modeling
A. General Models
B. Radon
C. Formaldehyde
D. Ozone
V, General Reviews
A. Treatises
B. Bibliographies
This trend may also reflect the early
emphasis on ventilation as the principal
control option. Few studies deal with
other control options (e.g., air purifica-
tion), and only one study considered
source modification to reduce emission
rates. In "Modeling" (Area IV), several
studies attempted to predict indoor
pollutant levels using mass-balance ap-
proaches. These models typically consider
one or perhaps a few pollutants and are
therefore incomplete in characterizin
indoor environment. Their accuracy i:
also limited by the input parameters, e.g.
source emission rates and mixing factors
In summary, based on a review of th<
articles contained in the annotate*
bibliography, several study areas appea
to deserve further investigation
including: (1) determining source emis
sion rates, especially with regard to thei
use in mathematical models; (2) furthei
study of control options (e.g., air purifiers
and source modification); and (3) morf
sophisticated modeling efforts tha
consider more than one or two pollutants
Twenty-three organizations considerec
active in indoor air quality research were
contacted by telephone. The repor
documents these contacts, summarizing
the information that was obtained. The
information includes the name of the
investigator, project sponsor, project title,
and a general description and categoriza-
tion of the research. Separate contac
summaries are provided for each project;
thus, a particular organization may have
several summaries.
Conclusions and
Recommendations
The review of current literature
(through December 1983) and the
telephone survey of prominent investiga-
tors indicate that most indoor air quality
research has been directed toward the
characterization and measurement of
indoor pollutants. Within this area, many
studies have sought to establish an
average concentration level of a pollutant
or the relationship between indoor and
outdoor pollutant levels.
A small but significant body of research
provides preliminary information on
source types and emissions. Particular
emphasis has been directed toward the
characterization of sources of
formaldehyde and home combustion
sources. Control and mitigation of indoor
air quality problems has generally
emphasized the use of ventilation
techniques.
Mathematical modeling of indoor air
concentrations has been attempted:
results indicate some success, based on
comparisons with pollutant monitoring
results.
Further study to characterize emission
rates from exclusively indoor sources
(e.g., kerosene heaters) would be
beneficial. Also of benefit would be
further study of control options other than
ventilation; e.g., source modification to
reduce emission rates or air purifying
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methods to reduce pollutant levels. The
development of mathematical models
could lead to a cost-effective mechanism
for assessing the total health significance
of indoor air quality. Expanding these
models to consider a wider range of
pollutants (or integrating them with
laboratory and field measurements of
input parameters) would provide a more
complete characterization of the indoor
environment.
E. Kashdan. J. Sickles, and M. Renade are with Research Triangle Institute,
Research Triangle Park. NC 27709.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "Review of Recent Research in Indoor Air Quality."
(Order No. PB 84-206 515; Cost: $17.50, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
fy U.S. GOVERNMENT PRINTING OFFICE. 1984 759-015/7752
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