United States
Environmental Protection
Agency
a nd_Development
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
EPA/600/SR-92/198 December 1992
or EPA Project Summary
Recommended Performance
Standard of the Florida
Radon Research Program
Susan E. McDonough and Ashley D. Williamson
This report is a revised version of a
support document for the performance
testing portion of the proposed Florida
statewide building standard for radon-
resistant construction. The support
document was developed by the Alter-
nate Performance Standard Develop-
ment Committee of the Florida Radon
Research Program (FRRP), commis-
sioned by the Florida Department of
Community Affairs. This report contains
the rationale and technical justification
for the version of the Performance Test-
ing Section (Section 5) of the standard
which was recommended by the Stan-
dard Development Committee, as well
as recommended text for the section.
The recommendations and draft stan-
dard language were based largely on
an FRRP research project which in-
volved study of short-term and long-
term average indoor radon concentra-
tions in 80 Florida houses for over a
year. At the time of the committee re-
port, this project had collected 6
months of data from roughly half the
houses and 3 months of data from the
remaining half. After a brief review of
the variability of indoor radon, the re-
port describes background, methodol-
ogy, data analysis strategy, and early
results from the short-/long-term radon
correlation project. These are followed
by a rationale for the recommended
standard section. Significant peer re-
view comments follow.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
This is a revised version of a Recom-
mended Code and Linking Document de-
veloped as a support document for the
performance testing portion of the pro-
posed Florida statewide building standard
for radon-resistant construction. The sup-
port document was developed by the Al-
ternate Performance Standard Develop-
ment Committee of the Florida Radon Re-
search Program (FRRP), commissioned
by the Florida Department of Community
Affairs (DCA). The mission of this commit-
tee and of four other FRRP Standards
Development Committees is to provide
technical assistance for the major phases
of development of the building standard.
This assistance consists of development
of the technical background and basis for
elements of the standard by review of
alternative strategies for indoor radon con-
trol, interpretation of results from FRRP-
sponsored and other research projects,
recommendation of research to meet out-
standing information needs relevant to the
standards, and recommending specific el-
ements of the standard.
The original version of this report, con-
taining the rationale and technical justifi-
cation for the recommended Performance
Testing Section (Section 5) of the stan-
dard, was issued in August 1990. The
recommended standard section itself is
included as Appendix A to the report.
These recommendations and draft stan-
dard language were based in large part
on an FRRP research project which in-
Printed on Recycled Paper
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volved study of short- and long-term aver-
age indoor radon concentrations in 80
Florida houses for over a year. At the time
of the development of these recommen-
dations, this project had collected 6 months
of data from roughly half the houses and
3 months of data from the remaining half.
Subsequent to the release of August
1990 report, several relevant events oc-
curred. The research project continued,
and data collection was completed in
March 1991, with at least a full year in 65
houses (five quarters in over half of these)
and somewhat less (two or three quar-
ters) in the remaining 15 houses. During
the course of the project, improved pre-
dictive threshold radon concentrations
were calculated each quarter based on
the growing pool of data generated by the
project. The draft final report was submit-
ted in June 1991 and was released as an
EPA final report in October 1991 after
technical and administrative review. That
report (Development of Alternate Perfor-
mance Standard for Radon Resistant Con-
struction Based on Short-Term/Long-Term
Indoor Radon Concentrations, EPA-600/
8-91-210a,b) contains a much more de-
tailed description of the project than the
present document, and should be used
for further reference.
The DCA issued the draft Standard for
Radon-Resistant Construction for public
comment in October 1990. The perfor-
mance testing section of that standard
incorporated the language of Appendix A
as modified by internal department rev'iew
and later in response to public comments.
The proposed standard was subsequently
withdrawn, revised, and renoticed as a
result of legal challenge, and was still in
the rule-making process in October 1991.
Later versions of the standard contained
different acceptance thresholds due to the
incorporation of revised predictions based
on more complete data from the research
project.
Concurrently with the initial rule-making
activities, the committee report was also
subjected to peer review in September
1990 by other scientists within the FRRP.
The peer review comments included both
technical and editorial comments concern-
ing the committee report, questions and
suggestions regarding the standard itself,
and recommendations for further research.
In order to maintain the historical integ-
rity of the original August 1990 committee
report, the peer review comments were
addressed. Obvious editorial deficiencies
were corrected in this revised version. Like-
wise, mathematical errors in the original
version were corrected, using only the data
that were available at the time of the origi-
nal report. The other comments and ap-
propriate responses have been summa-
rized in Appendix B of the report.
Background of Performance
Standard
Section 5 (Performance Testing) of the
proposed code for radon resistant con-
struction provides a performance testing
option as an alternative to fully engineered
radon controls which may not be cost-
effective or necessary in all parts of the
state. The philosophy of the performance
standard recommended in this text can be
briefly stated as a compromise between
conflicting needs in the light of measure-
ment uncertainty. First, as described be-
low estimates of long-term radon expo-
sure from single short-term radon mea-
surements are subject to considerable un-
certainty, which can be reduced only by
long-term or multiple measurements. The
state needs to have confidence that a
building actually will conform to the long-
term radon concentration standard set by
the Department of Health and Rehabilita-
tive Services (DHRS); therefore, the needs
of the state are best served either by a
longer testing period (which decreases
measurement uncertainty) or by a conser-
vative performance threshold (i.e., lower
than the DHRS standard). Builders and
developers need to minimize delays be-
tween construction and occupancy; there-
fore, the construction industry is best
served by as short a test period as is
feasible. The proposed standard was de-
veloped to offer optional measurement
devices arid sampling periods to address
both needs.
The FRRP Alternate
Performance Standard
Development Project
Methodology
The short- /long-term portion of the Al-
ternate Performance Standard Project in-
cludes the monitoring of approximately 80
houses in four regions of the state includ-
ing, Alachua, Dade, Leon, and Polk Coun-
ties. The houses were selected based on
the characteristics identified as common
to Florida housing stock such as:
Single family, single level, slab-on-
grade housing with forced air heating
and cooling
Low to moderate radon level - 2 to 20
pCi/L
Unmitigated (although two previously
mitigated houses were selected for
comparison in Polk County)
Air handler characteristics: split be-
tween houses with air handler inside
building shell (closet) and outside shell
(garage, attic)
Natural ventilation: about half of the
houses selected never use natural
ventilation for cooling.
Four types of radon measurement de-
vices have been selected for this study.
The devices include:
Radtrak alpha track detectors
High and low sensitivity electret pas-
sive environmental radon monitors
A 7-day passive diffusion barrier and
2-day open-face charcoal canisters
A Pylon AB-5 continuous radon moni-
tor with a passive radon detectors.
In order to develop a predictive relation-
ship between short-term measurements
and long-term (annual) average concen-
trations, a variety of short- and long-term
sampling approaches are currently em-
ployed in each study house. The devices
selected and their deployment periods are:
Alpha-track detector (deployed for 1
year or project duration)
Alpha-track detector (deployed for one
quarter eachfour per house)
Low sensitivity electret passive envi-
ronmental radon monitor (read on ap-
proximately 28-day intervals)
High sensitivity electret passive envi-
ronmental radon monitor (read on ap-
proximately 7- and 14-day intervals)
Seven-day charcoal canisters (1 week
per month per house)
Two-day charcoal canisters (1- or 2-
day deployment per month per house)
Pylon AB-5 with passive radon detec-
tor (rotated between houses approxi-
mately 4 weeks per house).
Data Analysis Strategy
An overall strategy for data analysis
was developed with certain presumptions
as to the form of the data. First, the distri-
bution of radon concentrations within a
typical house is assumed to be log-nor-
mal; within this framework predictive mod-
els for long-term radon levels are devel-
oped. The data analysis scheme outlined
in the full report was applied to two quar-
ters' data from the first set of 40 houses
and to one quarter's data from the second
set of 40 houses. First, some strong sug-
gestions of seasonal differences are
present, with the winter quarter averages
significantly higher than the spring aver-
ages. While a 6-month study period can-
not substitute for a full year, an argument
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can be made that the current data set is a
reasonable approximation for the variabil-
ity of a full year's data set.
Technical Rationale of the
Recommended Standard
The data collected and analyzed to date
in the FRRP Alternate Performance Stan-
dard project have been incorporated into
thresholds in the recommended code in
report Appendix A. The assumptions and
philosophy that have been used to de-
velop the standard are:
1. The goal of a building standard is
to reduce the long-term average
(annual or longer) radon concen-
tration in the building to be occu-
pied.
2. Short-term measurements in the
building will have uncertainty due
to (a) measurement accuracy of the
device used and (b) variability of
the indoor radon concentration with
time. Uncertainty due to effect (b)
can be reduced by increasing the
measurement time.
3. A performance test must be com-
pleted and the results known prior
to occupancy for practical enforce-
ment of a construction performance
standard. In view of the time pres-
sures on the construction industry,
the measurement period in a work-
able performance standard will
probably be a compromise between
the schedule needs of the builder
and the uncertainty of the radon
measurement.
4. The radon standard set by DHRS
is assumed to remain at 4 pCi/L.
5. The threshold for passing a short-
term performance test should be
conservative; i.e. low enough to
ensure that (within a confidence
level to be determined by the State)
the building will not have a long-
term average radon concentration
in excess of the DHRS standard if
a short-term performance test gives
results less than the threshold.
6. Thresholds of this type are being
developed for several device/mea-
surement period combinations, so
that the builder may elect to use a
shorter-duration test with a lower
pass/fail threshold in order to
achieve the same confidence that
the building will comply with the
standard.
7.
8.
Similarly, the project data have been
analyzed to allow the state to
choose thresholds based on differ-
ent levels of confidence according
to both its regulatory priorities and
the standard ultimately to be set by
DHRS.
If the effects of the time of year on
indoor radon concentration can be
quantified, an algorithm to account
for seasonal effects will be built into
the threshold criteria. If such an
algorithm cannot be developed, the
variability due to season must be
included in the total variability of
radon measurements in determin-
ing the thresholds for all times of
the year. (This approach has been
taken in the current recommenda-
tions.)
Model language for a performance stan-
dard developed by these steps, as well as
explanatory annotations, are contained in
the full report. The code language incor-
porates the possibility of several combina-
tions of device and measurement period.
No provision for incorporating "average"
seasonal variations in radon data is in-
cluded, due to lack of sufficient data on
the form of systematic seasonal differ-
ences.
'U.S. Government Printing Office: 1993 750-071/60163
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S. McDonough and A. Williamson are with Southern Research Institute, Birmingham,
AL 55305-5305.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "Recommended Performance Standard of the Florida
Radon Research Program," (Order No. PB93-122281/A S; Cos t: $ 17.00; s ubject 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:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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