United States
                                        Environmental Protection
                                        Agency
                          Office of         Air and Energy Engineering
                          Research and    Research Laboratory
                          Development    Research Triangle Park, NC 27711
                                                                                 EPA/600/9-91/005   March 1991
                        Radon  Mitigation  Research   Update
                                                                    Introduction
Project Highlights	1
  • Indoor Radon
    Research Program
  • Florida Radon Program
  • Measurements in Previously
    Mitigated Houses
  • Manual Updates
  • New Technical Manual
1991 International Symposium
on Radon and Radon Reduction
Technology _„„__„„—_...„
  • AEERL Papers
Update of RMB Papers and Reports ....
EPA Regional Offices	
Response Form ».._.»«„.«......«««.......„.
The Radon Mitigation Research Update is
the second in a series of research summaries
intended to provide recent information about
EPA's radon mitigation research activities
by the Air and Energy Engineering Research
Laboratory (AEERL) and to compile a list-
ing of  recent Radon Mitigation  Branch
(RMB) research findings.
AEERL plans to publish future updates ap-
proximately two times a year. If you would
like more information about specific research
activities or programs, you may contact the
appropriate RMB project officer at MD-54,
U.S. EPA, AEERL, Research Triangle Park,
NC 27711, or at the number listed below.
                             RMB Contacts
 Mike Osbome, Branch Chief
(919)5414113
• EPA radon mitigation research  and
  development program
A.B. "Chick" Craig
(919)541-2824
• Senior Physical Scientist - Radon
Tim Dyess
(919)541-2802
• Radon resistant new construction
Bruce Harris
(919)541-7807
• Radon diagnostics and measurement tech-
  nology
Bruce Henschel
(919)541-4112
• Radon mitigation in existing houses
Kelly Leovic
(919)541-7717
• Radon mitigation in schools
Ron Mosley
(919)541-7865
• Radon data analysis
John Ruppersberger
(919) 541-2432
• Radon barriers and block permeability
David Sanchez
(919)541-2979
• Mechanisms of radon entry and Florida
 Radon Research Program
                                        Project Highlights
Indoor Radon Research Program—Strategic
Plan
AEERL first embarked on an aggressive radon mitigation develop-
ment and demonstration research program in 1984. Since that time,
research has evolved from a program which focused on demonstrat-
ing mitigation techniques in houses with highly elevated radon levels,
to a multi-faceted research, development, and demonstration program
concerned with reducing radon to near-ambient levels (less than 1
pCi/L) in existing houses, new houses, and schools across the coun-
try.
This expanded effort responds to EPA's public health mission and the
1988 Indoor Radon Abatement Act's mandate to reduce radon-
related health risk by reducing indoor radon to near-ambient levels.
To meet the demands of this expanded effort, AEERL has recently
developed a 3-year Strategic Plan for the  Indoor Radon Research
Program that integrates the activities of  five otherwise separate
program areas—1) innovative and supporting technology, 2) existing
attached and unattached houses, 3) new houses (including pollution
prevention), 4) schools, and 5) technology  transfer—into one com-
prehensive research effort.
An increased emphasis has been placed on innovative/supporting
research in an effort to accelerate improvements in technology, lower
                                                        1
                   the cost of technology, and facilitate the delivery of this technology to
                   a larger and broader audience.
                   The Indoor Radon Research Program has five areas of major empha-
                   sis:

                     1) developing new and improved radon reduction methods through
                       a better understanding of fundamentals,
                     2) de-emphasizing the demonstration of currently available radon
                       mitigation technology in existing and new houses,
                     3) increasing the emphasis on mitigation system durability assess-
                       ments and operating cost analyses,
                     4) continuing to identify, develop, and demonstrate radon mitiga-
                       tion options for schools and non-residential child care facilities,
                       and
                     5) supplying a greater  variety of audience-specific technology
                       transfer products.

                   Utilizing this integrated approach, concepts developed in the Inno-
                   vative and Support Technology area will be demonstrated in existing
                   houses, new houses, and/or schools and other large buildings. Prod-
                   ucts resulting from each of these efforts will then be  incorporated
                   into technical guidance documents.

                                                     Printed on Recycled Paper

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Florida Radon Research Program
RMB has coordinated and completed the delivery of recommenda-
tions and draft technical support documents to the Florida Depart-
ment of Community Affairs for Standards for Radon-resistant Con-
struction and Mitigation. The results of this effort will be published
in 18 reports  covering recommendations for  1)  improved floor
barriers, 2) subslab depressurization systems, 3) HVAC specifica-
tions, 4) fill material specifications, and S) performance criteria. Data
gathered by the Florida Radon Research Program is available through
a central Geographic Information System (CIS) data base maintained
by the Geoplan Center of the University of Florida.
Program and project planning for continuation of the EPA/Florida
interagency research agreement has also begun. These plans include
the initiation of a 2-year research effort to enhance the technical basis
for the five task areas listed above, and to begin work on the
development of a radon potential mapping basis for application of
construction and mitigation standards. Work in all task areas will be
undertaken in unoccupied research houses with development verified
in newly constructed houses. Problem assessment and building
characterization studies for large buildings will start in FY 91. (For
additional information on this program contact D. Sanchez, Project
Officer.)

Measurements In Previously Mitigated Houses
RMB is conducting measurements in previously mitigated (18 months
or longer) test houses in an effort to establish the long-term effective-
ness and durability of various mitigation systems.
Researchers have placed 6-month Alpha Track Detectors (ATDs) in
a number of basement and slab-on-grade houses, mitigated by EPA
or EPA contractors, to gather data on post-mitigation radon levels.
Plans are under way to initiate similar activities in a large number of
houses mitigated by private sector companies. The results of this
study  will allow  RMB researchers  to  identify radon mitigation
systems/strategies that are not effectively maintaining indoor radon
levels below 4 pCi/L- Study findings will also help identify mitiga-
tion systems/strategies which show the greatest potential for reduc-
ing indoor radon levels to near-ambient levels.
Follow-up research will focus on identifying equipment and installa-
tion problems as well as house and soil characteristics which may
have contributed to system  failure. Research findings will be made
available through AEERL publications and in future issues of Radon
Mitigation Research Update. (For additional information contact B.
Harris, Project Officer.)

Update of Technical Manuals
AEERL is currently updating a number of  EPA technical guidance
manuals to better assist in the dissemination of the most timely and
accurate radon reduction research information. These updated manu-
als are scheduled for release later this year and include Radon
Reduction for Detached Houses (Technical Manual), and  Radon-
Resistant Construction Techniques for New Residential Construction
(Technical Guidance).

New Technical Manual
AEERL will also publish the first edition of EPA's Radon-Resistant
New School Construction Manual. This  new  manual will be based
largely on RMB's recent experience in existing schools and previous
experience with radon-resistant new house  construction techniques.
It will provide the most up-to-date  information available on the
design of radon-resistant/easy-to-mitigate new school buildings.
       1991  International Symposium  on  Radon  and Radon
                                    Reduction Technology
Final plans are being made for the 1991 International Symposium on
Radon and Radon Reduction Technology "A New Decade of Progress"
to be held April 2-5 at the Adam's Mark Hotel in Philadelphia, PA.
EPA will co-sponsor the event with  the Conference of Radiation
Control Program Directors (CRCPD).  This is the third such confer-
ence to serve as a forum for the exchange of technical information.
The program includes 77 oral and 52 poster presentations in addition
to 13 invited papers.
Over 600 representatives from radon mitigation companies, local,
state, and federal governments, equipment manufacturers, academia,
and research and development firms are expected to attend.  The
following agenda provides a summary of the  conference's  four
session days:
Tuesday, April 2
  Session I: Government Programs and Policies Relating to Radon
  Session II: Radon-Related Health Studies
  Poster Session: All Posters Relating to Sessions I, n, and in
Wednesday, April 3
  Session HI: Measurement Methods
  Session IV: Radon Reduction Methods
  Session V: Radon Entry Dynamics
  Session VI: Radon Surveys
  Poster Session: All Posters Relating to Sessions IV, V, VI, and Vn
Thursday, April 4
  Session VII: State Programs and Policies Relating to Radon
  Session VDI: Radon Prevention in New Construction
  Session DC: Radon Occurrence in the Natural Environment
  Poster Session: All Posters Relating to Sessions VHI. IX, and X
Friday, April 5
  Session X: Radon in Schools and Large Buildings
If you would like more information about the symposium, please
contact Pat Heightchew, CRCPD, Inc., 205 Capital Avenue, Frank-
fort, KY 40601, (502) 227-4543. On-site registration will be avail-
able from 4 to 9 pjn. Monday, April  1, and from 7 a.m. to 5 p.m.
Tuesday through Thursday.

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AEERL Papers
This section lists and briefly describes the 18
RMB oral papers and poster papers which
will be presented at the 1991 International
Symposium. RMB Project Officers and lead
authors are listed for each paper. For addi-
tional information on these research activi-
ties, please refer to the symposium pre-prints
(available with symposium registration) or
contact the appropriate RMB Project Officer
listed on page 1.

Measurement Methods
Predicting Long-term Indoor Radon Lev-
els from Short-term Measurements:
Evaluation of a Method Involving Tem-
perature Correction; R.B. Mosley, Project
Officer, and T.A. Reddy. Oral Paper
Daily averages of year-long continuous radon
measurements in three houses were used to
present a method for temperature-correcting
single short-term measurements  of indoor
radon in order to predict long-term averages.
The thermal stack effect was demonstrated
to have the most important single influence
on radon concentrations.  The method was
found to reduce the uncertainty in estimated
annual averages of radon concentrations sig-
nificantly in one  house, moderately in the
second, and marginally in the third.
Correlation Between  Short-term and
Long-term Indoor Radon Concentrations
in Florida Houses; D.C. Sanchez, Project
Officer, and S.E. McDonough. Poster Pa-
per
Eighty study homes, representative of typical
Florida housing construction, with indoor
radon concentrations in the 2-20 pCi/L range,
are being simultaneously monitored using
long-term and short-term monitors.
Data have been analyzed to isolate system-
atic seasonal variations and to derive confi-
dence limits for predicted long-term (annual)
averages  from single or multiple short-term
measurements. Thresholds have been deter-
mined below which a single short-term mea-
surement can provide specific confidence
that the long-term average radon level does
not exceed 4 pCi/L. These results have been
incorporated into Florida's draft building
standards.
Soil Gas Measurement Technologies; D.C.
Sanchez, Project Officer, and H.E. Rec-
tor. Poster Paper
This paper  discusses soil-based  radon and
radium measurement technologies capable
of providing useful information for evaluat-
ing land radon potentials.  Findings indicate
that, while the use of soil gas measurements
to estimate radon potentials is still evolving,
both radium- and soil-gas-based measure-
ments can help identify land areas warrant-
ing special  attention  and  consideration for
radon-resistant construction.
Radon Reduction Methods
Causes of Elevated Post-mitigation Radon
Concentrations in Basement Houses Hav-
ing Extremely High Pre-mitigation Val-
ues; D.B. Henschel, Project Officer, and
A.G. Scott. Oral Paper
Forty Pennsylvania  basement houses with
1985-87 pre-mitigation radon levels in the
50 to 600 pCi/L range were reevaluated in
1989-90. The  primary single cause of re-
sidual (post-mitigation) elevated radon lev-
els in houses using active soil depressuriza-
tion (ASD) was found to be reentrainment of
high-radon fan exhaust In houses using block
wall depressurization  systems, inadequate
sub-slab depressurization appeared to be the
major  cause of problems. For other than
ASD systems, inherent limitations within the
systems are  commonly the primary single
cause of residual levels. Airborne radon re-
sulting from radon  in well water was an
important secondary contributor in some
houses.
Natural Basement Ventilation as a Radon
Mitigation  Technique;  R.B.  Mosley,
Project Officer, and A. Cavallo. Oral Pa-
per
The effectiveness of natural  ventilation in
reducing indoor radon levels was studied in
two basement houses. The study found that a
factor of two increase in the ventilation rate
(opening basement windows) corresponded
to as much as a factor of eight reduction in
radon concentration. The researchers found
a corresponding, but much smaller, decrease
in the  pressure differentials (radon  driving
forces) across the basement slabs.
Control  Of Radon Releases in Indoor
Commercial Water Treatment; B. Harris,
Project Officer, and A.B. Craig.  Poster
Paper
Municipal treatment facilities, industrial
process facilities, and other water treatment
facilities may be at risk for high indoor radon
levels. Water laden with relatively low levels
of radon (400 to 600 pCi/L), when used in
high volume commercial operations, may
release enough radon to result in indoor levels
in excess of 100 to 300 pCi/L in treatment
rooms and adjoining offices.
Elevated radon levels identified in the Fish
and Wildlife Service's National Fish Hatch-
eries were controlled by vacuum-stripping
the incoming water and exhausting the radon
outdoors. Hooding and exhausting air from
immediately around discharge  points also
proved to be successful in reducing indoor
levels.
Radon Mitigation  Failure Modes; D.B.
Harris, Project Officer, and WM. Yeager.
Poster Paper
Residential mitigation systems fail for a va-
riety of reasons and some failures may not be
immediately  recognized by residents. This
study identified three primary failure catego-
ries (design flaws, component problems, and
occupant activities) and reviewed examples
of failure modes in each category. Results
indicate that some failures could be avoided
if mitigators would design systems to mini-
mize failures, install  system monitors,  and
instruct homeowners  on continued system
maintenance.

Radon Entry Dynamics
Radon Entry  into  Dwellings  Through
Concrete Floors;  D.C. Sanchez, Project
Officer, and K.K. Nielson. Oral Paper
Porosities, radon diffusion coefficients, and
air permeability coefficients were measured
for typical Florida slab-on-grade housing ce-
ment mixes. Findings suggest that radon dif-
fusion  through an intact slab may account
for indoor radon concentrations of 2 pCi/L if
greater than 3,000  pCi/L exists in the  sur-
rounding soils. Radium concentrations of 5
pCi/g in the concrete  similarly may account
for more than 1 pCi/L of indoor radon. Dif-
fusion measurements  also exhibited a corre-
lation  with the water/cement ratio of the
concretes.
Model Calculations of the Interaction of a
Soil Depressurization  System  with  the
Radon Entry Process; R.B. Mosley, Project
Officer. Poster Paper
This study uses a simplified analytical model
of radon transport and entry into  houses to
estimate the influence of a mitigation system
on the entry process. Modifications of the
diffusive flux  and the  entry rate into the
building by the action of the mitigation  sys-
tem are estimated in order to determine the
total effect on emission of radon to the atmo-
sphere.
A Modeling Examination Of Parameters
Affecting Radon and Soil Gas Entry into
Florida-style Slab-on-grade Houses; D.C.
Sanchez, Project Officer, and R.G. Sextro.
Poster Paper
The influence of soil,  backfill, and construc-
tion characteristics on  radon and soil gas
entry is examined using a two-dimensional
finite difference model employing cylindri-
cal symmetry. At a constant building depres-
surization, steady state  pressure, flow,  and
radon concentration fields were predicted.
The model predicts that changes in backfill
permeability will have significant effects on
radon entry, while changes in block  wall
permeability are somewhat offset by in-
creased flow and entry through other struc-
tural gaps.
Soil Gas and Radon Entry Potentials for
Slab-On-Grade Houses; D.B. Henschel,
Project Officer, and B.H. Turk. Poster
Paper
A simple model is used to address the impor-
tance of subslab communications testing, in-
cluding measurements of radon concentra-

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dons and soil gas flows  through slab test
holes, in determining the number and loca-
tion of active subslab depiessurization (ASD)
suction holes. Findings suggest that pipes for
ASD systems should be located along the
perimeter of slabs and only at areas of rela-
tively high radon entry potentials. The model
also suggests that three or  fewer properly
placed suction points will often reduce in-
door radon levels to below 2 pCi/L, even in
problem houses.

Radon Prevention In New
Construction
Building Radon Mitigation into Inacces-
sible Crawlspace New Residential  Con-
struction;  B. Harris and A.B.  Craig,
Project Officers, and J. Haynes. Oral Pa-
per
Single,  duplex, and  quadruple*  buildings
were  constructed utilizing  a below-grade
wood floor construction over an inaccessible
crawl space due to highly expansive  soils.
Initial  studies demonstrated the need for
complete sealing of the floor system until a
negative pressure could be maintained under
each comer of the floor (at least 2.5  Pa).
Early  measurements indicated radon levels
of about 100 pCi/L in the unmitigated crawl
space. Tests in the first buildings completed
showed all units below 25 pCi/L except for
one unit where the depressurization fan had
been turned off. This unit measured 16 pCi/L
and dropped to below 25 pCi/L when the
fan was activated.
The Effect of Subslab Aggregate  Size on
Pressure Field Extension; A.B.  Craig,
Project Officer, and K. Gadsby. Oral Pa-
per
The effects of particle size and particle size
distribution on sub-slab pressure field exten-
sion (PFE) were evaluated using laboratory
tests simulating conditions  existing under
slabs. Findings indicate that PFE is propor-
tional to the average stone size (the smaller
the stone size, the less the PFE), the  stone
size distribution (the narrower the stone size
distribution, the greater the void volume and
hence the PFE), and the shape of the stone
(the smoother  the shape of the stone, the
lower the void volume and hence the PFE).
Preliminary Results Of HVAC System
Modifications  To Control Indoor Radon
Concentrations; TJV1. Dyess, Project Offi-
cer, and T.M. Brennan. Poster Paper
Preliminary testing in one energy-efficient
house indicates that residential forced-air
furnaces can be used to pressurize basements
and prevent radon entry. By adding a supply
air duct in the basement and modifying the
HVAC unit to run continuously on low speed,
300 cfm of air was supplied to the basement
maintaining +4 Pa relative to outdoors. The
average radon levels dropped from 143 to
1.2 pCi/L. Further research will analyze the
economic impact of these modifications and
determine their viability as a low cost alter-
native to sub-slab depressurization in new
construction.

Radon In Schools
HVAC System Complications  and Con-
trols  for Radon  Reduction in School
Buildings; K.W. Leovic, Project Officer.
Oral Paper
Initial data collected in four schools in Colo-
rado, Maryland, Virginia, and Washington
State confirm that, when outdoor air supply
is increased using HVAC systems (forced air
or unit ventilator), radon levels can be re-
duced. Depending on HVAC system design
and initial radon levels, this approach may or
may not be able to reduce levels to below 4
pCi/L. Table 1 illustrates reductions achieved
by pressurization of classrooms (using exist-
ing HVAC systems) in one Washington State
school.
Note that the classroom-to-hall doors had to
be kept closed for  the unit ventilators to
reduce average levels to below 4 pCi/L, al-
though radon spikes (as high as 25 pCi/L)
still occurred.
TabU 1.  Average Radon Levels In Waikington School During One Week
                Normal Operation                  Test Operation
Average Radon
Location
pCUL (max)
Room 139 2.6
Room 140 S3
Room 141 4&
Average 42
(27)
(29)
(32)
(29)
Time Door
Closed
97
92
88
92
Average Radon
pCUL (max)
12
32
2J
22
(17)
<7)
(25)
(16)
Time Door
Closed
(*)
76
74
75
75
Subslab
Radon
Sniff. August 90
pCUL
400
500
700
533
Research over the next year will be focused
on determining optimal HVAC system op-
erations and  limitations of pressurization.
Long-term research will include a compari-
son of HVAC modification and active subslab
depressurization in the same schools.
Design of Radon-Resistant and Easy-To-
Mitigate New School Buildings; A.B. Craig,
Project Officer, and K.W.  Leovic.  Oral
Paper
Recent experience in existing schools, new
house construction, and limited experience
in new school construction  indicates that
radon resistant features can and should be
incorporated into new school buildings in
high risk areas. Radon-resistant features work
by reducing the potential for radon (soil gas)
entry and facilitating cost effective post-con-
struction mitigation. Pre-construction features
include: designing, installing, and operating
the HVAC system to pressurize the building
providing adequate makeup air for building
exhausts; laying down a minimum of 4 in. of
clean,  coarse subslab aggregate;  limiting
subslab barriers to air movement; and rough-
ing in subslab depressurization points.
Design and Application of Active Soil De-
pressurization Systems in School Build-
ings; K.W. Leovic, Project Officer. Poster
Paper
Recent research  on  active subslab depres-
surization (ASD) systems in  two Kentucky
and two Maine  schools indicates that: 1)
schools with low permeability material (i.e.,
sand) under the slab may require higher suc-
tion  fans to  adequately  depressurize the
subslab area; 2) utility tunnel depressurization
may be an effective and relatively inexpen-
sive technique if the tunnels are not too leaky
and do not contain asbestos; 3) ASD systems
are typically preferred to passive systems in
existing schools  to maximize radon reduc-
tions; and 4) subslab pressure field extension
(based on measurements conducted in one
school) is greater when suction is applied to
an interior point rather than from the building
exterior.
A Comparison of Radon Mitigation Op-
tions for Crawlspace School Buildings;
K.W. Leovic, Project  Officer, B.E.  Pyle.
Poster Paper
Research in one Tennessee school constructed
over a crawl space indicates  that sub-mem-
brane depressurization is the  most effective
technology for reducing radon levels in both
the classrooms and the crawl space. Crawl
space depressurization was effective  in re-
ducing levels in the classrooms but increased
levels in the crawl space by a factor of two to
three. Both pressurization and natural  venti-
lation of the crawl space were found to be
less  effective technologies than sub-mem-
brane depressurization  or crawl space  de-
pressurization.

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               RMB  Papers and Reports Since  Last Update
 Reports Since Last Update:
 "Testing of Indoor Radon Reduction Tech-
 niques  in Central Ohio Houses: Phase  2
 (Winter 1988-89),"  Findlay, W.O., A.
 Robertson, and A.G. Scott, submitted to EPA
 by Acres International Corp., EPA-600/8-
 90-050, May 1990  (NTIS  No. PB90-
 222704).*
 'Testing of Indoor Radon Reduction Tech-
 niques in 19 Maryland Houses," Gilroy, D.G.,
 and W.M.  Kaschak. submitted to EPA by
 COM Federal Programs Corp., EPA-600/8-
 90-056, June 1990 (NTIS No. PB90-244393).
 "Radon Mitigation Studies: Nashville Dem-
 onstration," Pyle, B.E., and A.D. Williamson,
 submitted to EPA by Southern Research In-
 stitute, EPA-600/8-90-061, July 1990 (NTIS
 No. PB90-257791).
 "Interim  Radon-Resistant Construction
 Guidelines for Use in Florida—1989," Pugh,
 T.D., submitted to  EPA by Florida A&M
 University, EPA-600/8-90-062, August 1990
 (NTIS No. PB90-265349).
"Engineering Design Criteria for Sub-slab
Depressurization Systems  in Low-perme-
ability Soils," Fowler, C.S., et aL, submitted
to EPA by Southern Research Institute, EPA-
600/8-90-063, August 1990 (NTIS No. PB90-
257767).
"Investigation of Radon Entry and Effective-
ness of Mitigation Measures in Seven Houses
in New Jersey," Dudney, C.S., et al., submit-
ted to EPA by DOEADak Ridge National
Laboratory, EPA-600/7-90-016, August 1990
(NTIS No. DE89016676).
"Identification of Candidate Houses for the
North Florida Portion of the Florida Radon
Mitigation Project," Roessler, G.S., et al.,
submitted to EPA by University of Florida,
EPA-600/8-90-070, September 1990 (NTIS
No. PB90-274077).
"Summary of EPA's Radon Reduction Re-
search in Schools During 1989-90," Leovic,
K.W., prepared in-house by EPA, EPA-600/
8-90-072, October 1990 (NTIS  No. PB91-
102038).
'Testing of Indoor Radon Reduction Tech-
niques in Basement Houses Having Adjoin-
ing Wings," Messing, M., submitted to EPA
by Infiltec, EPA-600/8-90-076, November
1990 (NTIS No. PB91-125831).
"Follow-Up Annual Alpha-Track Monitor-
ing in 40 Eastern Pennsylvania Houses with
Indoor Radon Reduction Systems (Decem-
ber 1988-December 1989)," Scott, A.G., and
A. Robertson, submitted to EPA by American
ATCON, EPA-600/8-90-081, November
1990 (NTIS No. PB91-127779).
Symposia Presentations:
"Building HVAC/Foundation Diagnostics for
Radon Mitigation in Schools: Part 2," Leovic,
K.W., D. B. Harris,  and A. B. Craig, pre-
sented at Indoor Air 1990, Toronto, Canada,
August 1990.
"Planning for Quality in Radon Mitigation,"
Ford, J. S., and B. Harris, presented at Indoor
Air 1990, Toronto, Canada, August 1990.
"Radon Diagnostics  for Schools," Leovic,
K.W., A. B. Craig, and D. B. Harris, pre-
sented  at 83rd  Annual  AWMA Meeting,
Pittsburgh, PA, June 24-29, 1990.
                                                                            * All reports with NTIS members are available
                                                                             (prepaid) from the National Technical Informa-
                                                                             tion Service, 5285 Port Royal Road, Spring-
                                                                             field, VA 22161 (phone 703/487-4650).
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