v>EPA
           United States
           Environmental Protection
           Agency
             Air And
             Radiation
             (6604J)
EPA 4eg-R-93-QQa-
June 1993
Protocols For Radon And
Radon Decay Product
Measurements In Homes
                                        \
                                      Printed on Recycled Paper

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                             Preface
This document, the Protocols for Radon and Radon Decay Product
Measurements in Homes (EPA 402-R-92-003, May 1993), is a guidance
document.  However, one condition of participation in the Agency's National
Radon Measurement Proficiency Programs for radon measurement and radon
reduction (mitigation) proficiency, is conformance with these protocols.
Conformance with its companion document, the Indoor Radon and Radon
Decay Product Measurement Device Protocols (EPA 402-R-92-004, July 1992),
is also a condition of participation in the Proficiency Programs.

Together these protocol documents provide the technical support for the
Agency's radon policy and guidance to consumers that is contained in, but not
limited to, the Home Buyer's and Seller's Guide to Radon (EPA 402-R-93-003,
March 1993), A Citizen's Guide to Radon (EPA 402-K-92-001), and the
Consumer's Guide to Radon Reduction (EPA 402-K-92-003, August 1992).

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                                 CONTENTS
 Section

 List of Exhibits	v


 Section 1:  INTRODUCTION	1.1


 Section 2:  DISCUSSION OF GUIDELINES PRESENTED IN THE
           CITIZEN'S GUIDE TO RADON

      2.1   Introduction and Summary	2-1

      2.2   Measurement Location	2-3

      2.3   Initial Measurements

           2.3.1  Rationale	  2-4

           2.3.2 Closed-Building Conditions ...	2-5

           2.3.3 Interpretation of Initial Measurement Results	2-6

      2.4   Follow-Up Measurements

           2.4.1  Rationale	2-7

           2.4.2  Short-Term and Long-Term Follow-Up Testing	2-7


Section 3:   DISCUSSION OF GUIDELINES PRESENTED IN THE HOME BUYER'S
          AND SELLER'S GUIDE TO RADON

      3.1   Introduction    	3_1

      3.2   Options for Real Estate Testing

          3.2.1  Option 1: Sequential Testing	3.4

          3.2.2  Option 2: Simultaneous Testing	3.4

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                 3.2.2.1  Both Measurement Results Equal To or Greater
                        Than 4 pCI/L	3-4
                 3.2.2.2  Both Measurement Results Less Than 4 pCi/L 	3-6
                 3.2.2.3  One Measurement Result Greater Than 4 pCi/L,
                        and One Measurement Result Less Than 4 pCi/L	3-6
                 3.2.2.4  Precision Requirements	3-6
                 3.2.2.5  Recommended Language for Informing the
                        Client that a Retest is Warranted  	3-7
           3.2.3  Option 3: Active Monitor Testing 	3-7
      3.3  Measurement Location	3-8
      3.4  Measurement Checklist	3-9
      3.5  Interference-Resistant  Testing	3-10
           3.5.1  Influencing Test Area Concentration	3-11
           3.5.2  Equipment Interference	3-12
           3.5.3  Preventing Interference 	3-12
           3.5.4  Interference-Resistant Detectors	3-13

Section*  GENERAL PROCEDURAL RECOMMENDATIONS
      4.1   Introduction    	4-1
      4.2  Initial Client Interview	4-1
      4.3  Measurement Recommendations
           4.3.1 Selecting a Measurement Approach	 4-1
           4.3.2 Written Measurement Guidance	4-2
           4.3.3 Conditions for a Valid Measurement	4-3

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           4.3.4 Non-interference Controls	4-3
           4.3.5 Measurement Documentation  	4-4
      4.4   Quality Assurance in Radon Testing  	4-5
           4.4.1  Calibration Measurements	4-5
           4.4.2 Known Exposure Measurements	 4-5
           4.4.3 Background Measurements	4-6
           4.4.4 Duplicate Measurements	4-7
           4.4.5 Routine instrument Performance Checks	4-7
           4.4.6 Quality Assurance Plans 	4-7
      4.5   Standard Operating Procedures	4-8
      4.6   Providing Information to Consumers	4-8
      4.7   Reporting Test Results	4-9
      4.8   Temporary Risk Reduction Measures  	4-10
      4.9   Recommendations for Mitigation	4-10
      4.10  Worker Safety  	4-10

Appendix A: STATE AND EPA REGIONAL RADON OFFICES
      A.1   State Radiation and Radon Offices 	A-1
      A.2   EPA Regional Radiation (Radon) Program Managers	A-7

Appendix B: INTERPRETATION OF THE RESULTS OF SIMULTANEOUS
           MEASUREMENTS
      B.1   Assessment of Precision	B-1
      B.2   Example Control Charts for Precision  	B-2
                                     iii

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            B.2.1  Sequential Control Chart Based
                  on Coefficient of Variation  	B-3

            B.2.2  Sequential Control Chart Based on
                  Relative Percent Difference	B-4

            B.2.3  Range Control Chart			B-8

      B.3"   Interpretation of Precision Control Chart	B-10
Glossary
G-1
References
R-1
                                       IV

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                              LIST OF EXHIBITS
Exhibit Number and Title
1-1 EPA Documents Providing Guidance on Radon Measurements	1-2
1-2 Radon and Radon Decay Product Measurement Method Abbreviations	1-4
2-1 Recommended Testing Strategy for Determining the Need for
    Mitigation in Homes	2-2
3-1 Radon and Radon Decay Product Measurement Method Categories	3-3
3-2 Deciding on a Retest When Measurements Vary Significantly  	3-5
A-1 Map of EPA Regions	  A-8
B-1 Control Chart for Coefficient of Variation Based on an
    "In Control" Level of 10 Percent	  B-5
B-2 Control Chart for Relative Percent Difference Based on an
    "In Control" Level of 14 Percent 	  B-6
B-3 Control Chart for Relative Percent Difference Based on an
    "In Control" Level of 25 Percent 	  B-7
B-4 Range Control Chart to Evaluate Precision	  B-9
B-5 Criteria for Taking Action for Measurements Outside
    the Warning Level 	  B-11

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                          Section 1: INTRODUCTION

    This document presents the U.S. Environmental Protection Agency's (EPA)
technical guidance for measuring radon* concentrations in residences.  It contains
protocols for measuring radon for the purpose of deciding on the need for remedial
action, as presented in the 1992 Citizen's Guide to Radon (EPA 402-K-92-001; U.S.
EPA 1992a), and in the Home Buyer's and Seller's Guide to Radon (EPA 402-R-93-
003; U.S. EPA 1993).

    The guidance for determining the need for mitigation is different in several key
aspects from previously issued recommendations, and this document supersedes a
previous report (EPA 520/1-86-014-1) published in February,  1987  (U.S. EPA 1987).
The technical basis for these policy changes is supplied in the Technical Support
Document for the 1992 Citizen's Guide to Radon (EPA 400-R-92-011; U.S.
EPA 1992g), and the revised policies are described in Section 2 of this report.

    Section 3 of this report describes the Agency's recommended protocols for
measuring radon for a real estate transaction.  This guidance elaborates on Agency
recommendations published in the Home Buyer's and Seller's Guide to Radon (EPA
402-R-93-003; U.S. EPA 1993). The radon testing guidelines in the Home Buyer's
Guide were developed specifically to deal with the time-sensitive nature of home
purchases and sales and the potential for radon device interference. The guidelines
are somewhat different from those in other EPA publications, such as the 1992
Citizen's Guide to Radon (EPA 402-K-92-001; U.S.  EPA 1992a), which provide radon
testing and reduction information for non-real estate situations. Therefore, Sections 2
and 3 of this document will have different guidance for different situations.

    This report is limited to discussions of Agency guidance regarding detector
placement, measurement duration, multiple measurements, and the interpretation of
measurement results.  EPA has also issued a technical report describing
measurement techniques, titled Indoor Radon and Radon Decay Product
Measurement Device Protocols (EPA 520-402-R-92-004) and published in 1992 (U.S.
EPA 1992c).  That report provides technical information for measuring radon
concentrations with continuous radon monitors, alpha track detectors, electret ion
chambers, charcoal canisters, unfiltered alpha track detectors, and grab radon
techniques; it also provides guidance for measuring radon decay product
concentrations with continuous working level monitors, radon progeny integrating
sampling units, and grab radon decay product techniques.  Copies of the Indoor
Radon and Radon Decay Product Measurement Device Protocols may be obtained
by  contacting your State or EPA Regional radon office (Appendix A). A list of EPA
documents providing guidance on radon measurements appears in Exhibit 1-1.
* The term "radon" refers to radon-222 and its decay products unless otherwise noted.
                                      1-1

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                           Exhibit 1-1


  EPA Documents* Providing Guidance on Radon Measurements
Title of Document
A Citizen's Guide to Radon
(U.S. EPA 1992a)
Consumer's Guide to Radon Reduction
(U.S. EPA 1992b)
Indoor Radon and Radon Decay Product
Measurement Device Protocols
(U.S. EPA 1992c)
Interim Radon Mitigation Standards
(U.S. EPA 1992d)
Home Buyer's and Seller's Guide to Radon
(U.S. EPA 1993)
Protocols for Radon and Radon Decay Product
Measurements in Homes
EPA Document Number
EPA 402-K-92-001
EPA 402-K-92-003
EPA 520-402-R-92-004
Regional Training Centers
(see below)
EPA 402-R-93-003
EPA 402-R-92-003
 These documents are available from the U.S. Government Printing Office
 Superintendent of Documents, Mail Stop: SSOP, Washington, D.C. 20402-
 9328; from the National Technical Information Service, U.S. Department of
 Commerce, Springfield, Virginia 22151; or your State or EPA Regional radon
 office.
EPA Regional Radon Training Centers-


Eastern Regional Radon Training Center, Rutgers University; (908)-932-2582.


Southern Regional Radon Training Center, Auburn University; (205)-844-6271.


Western Regional Radon Training Center, Colorado State University (303)-
491-7742.                                                         '


Northern Regional Radon Training Center, University of Minnesota; (612)-624-
6786.
                              1-2

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    This report provides guidelines that are primarily intended to aid State radiation
control programs, other organizations conducting indoor radon measurements, and
homeowners who want detailed information on radon measurements. The guidelines
herein can be adopted as part of a State program or can be provided by States to
interested individuals as recommendations. Adherence to these guidelines is a
requirement for participation in the National Radon Measurement Proficiency (RMP)
Program (EPA 520/1-91-006; U.S. EPA 1991). The method designations used in the
RMP Program are listed in Exhibit 1-2.  A two-letter code for each method has been
adopted, although ATDs (AT), RPISUs (RP), and EiCs/ECs (ES or EL) may still be
referred to by their traditional acronyms.

    EPA recognizes that radon concentrations in buildings may vary over time (Arvela
el aj- 1988, Dudney et a|. 1990, Fleischer and Turner 1984, Furrer et aJL  1991, Gesell
1983, Harley 1991, Hess 1985, Martzet a[. 1991, Nyberg and Bemhardt 1983, Perritt
et a}. 1990, Ronca-Battista and Magno 1988, Steck 1992, Stranden et a]. 1979,
Wilkening and Wicke 1986, Wilson งt a]. 1991). Furthermore, concentrations at
different locations in the same house often vary by a factor of two or more (Arvela iet
a]. 1988, Furrer et a]. 1991, George et M-1984, Hess 1985, Keller et aj. 1984,  Put and
deMeijer 1988, Steck 1992). EPA has carefully evaluated these findings, as well as
other factors (EPA 400-R-92-011; U.S. EPA 1992g), and has developed policies for
ensuring that the most representative and useful information is supplied by the
measurement results.  These guidelines may be evaluated periodically and refined to
reflect the increasing knowledge of, and experience with, indoor radon.          ,

    EPA recommends that initial measurements be short-term tests performed under
closed-building conditions. An initial short-term test, which lasts for two to 90 days,
ensures that residents are informed quickly should a home contain very high radon
levels.  Long-term tests give a better estimate of the year-round average radon level.
The closer the long-term test is to 365 days, the more representative it will be of
annual average radon levels.
                                      1-3

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                          Exhibit 1-2



Radon and Radon Decay Product Measurement Method Abbreviations
I METHOD CATEGORY
Continuous Radon Monitors
Alpha Track Detectors
Electret Ion Chambers
Short Term
Long Term
Activated Charcoal Adsorption Devices
(formerly called charcoal canisters)
Charcoal Liquid Scintillation
I Three-day Integrating Evacuated Scintillation Cells
| Pump/Collapsible Bag Devices
I (24 hour samplej
I Grab Radon Sampling
Scintillation Cells
Activated Charcoal
Pump-Collapsible Bag
Unfiltered Track Detectors
Continuous Working Level Monitors
Radon Progeny Integrating Sampling Units
Grab Sampling - Working Level
Abbreviations
Common
CRM
ATD
EIC/EC
CC
CLS



UTD
CWLM
RPISU

RMP
Method
CR
AT
ES
EL
AC
LS
SC
PB
GS
GC
GB
UT
CW
RP
GW
                            1-4

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            Section 2: DISCUSSION OF GUIDELINES PRESENTED IN
                       THE CITIZEN'S GUIDE TO RADON

2.1 INTRODUCTION AND SUMMARY

    The Citizen's Guide to Radon (EPA 402-K-92-001; U.S. EPA 1992a) presents a
measurement strategy for assessing radon levels in homes for the purpose of
determining the need for remedial action. This measurement strategy is intended to
reduce the risk to public health from exposure to radon in air in homes.  The strategy
begins with an initial measurement made to determine whether a home may contain
radon concentrations sufficient to cause  high exposures to its occupants.

    EPA recommends that initial measurements be short-term tests placed in the
lowest lived-in  level of the home, and performed  under closed-building conditions. An
initial short-term test ensures that residents are informed quickly should a home
contain very high levels of radon. Short-term tests are conducted for two days to 90
days. Closed-building conditions (Section 2.3.2) should be initiated at least 12 hours
prior to testing for measurements lasting less than  four days, and are  recommended
prior to tests lasting up to a week.

    If the short-term measurement result is equal to or greater than 4  picocuries per
liter (pCi/L), or 0.02 working levels (WL),  a follow-up measurement is recommended.
Follow-up measurements are conducted  to confirm that radon levels are high enough
to warrant mitigation.  If the result of the  initial measurement is below 4 pCi/L, or 0.02
WL, a follow-up test is not necessary.  However,  since radon levels change over time,
the homeowner may want to test again sometime in the future, especially if living
patterns change and a lower level of the  house becomes occupied or used regularly.

    There are two types of follow-up measurements that may be conducted, and the
choice depends, in part, on the results of the initial test:  An initial measurement result
of 10 pCi/L (or 0.05 WL) or greater should be followed by a second short-term test
under closed-building conditions. If the result of the initial measurement is between 4
pCi/L (or 0.02 WL) and 10 pCi/L (or 0.05 WL), the follow-up test may be made with
either a short-term or a long-term method.  Long-term tests are conducted for longer
than 90 days, and give a better estimate  of the year-round average radon level. The
closer the long-term measurement is to 365 days, the more representative  it will be of
annual average radon levels. On the other hand, short-term tests yield results more
quickly and can be used to make mitigation decisions. If the long-term follow-up test
result is 4 pCi/L, or 0.02 WL, or higher, EPA recommends remedial action.  If the
average of the initial and second short-term results is equal to or greater than 4 pCi/L,
or 0.02 WL, radon mitigation is recommended. These recommendations are
summarized in Exhibit 2-1.
                                     2-1

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                              Exhibit 2-1
                  Recommended Testing Strategy for
             Determining the Need for Mitigation in Homes
  Perform initial short-term radon measurement
  * or 0.02 WL
  *• or 0.05 WL
                                                    If the result is
                                                     > 10 pOi/L**
                                                     or results
                                                     are needed
                                                      quickly
 If the result
is>4pCi/L*
    but
 < 10 pCi/L
If the result
is<4pCi/L*
A follow-up test is
not necessary now
 Consider testing
   again in the
 future, however,
  and if a lower
 level (basement)
  becomes more
 frequently used,
   test there.
 Perform a
short-term or
 a long-term
  follow-up
measurement
                                                   A short-term
                                                    follow-up
                                                   measurement
                                                       is
                                                    performed
                          Average the
                          results of the
                           initial arid
                           follow-up
                           short-term
                         measurements
                          A long-term
                           follow-up
                         measurement
                              is
                          performed
                Is this
                result
              < 4 pCi/L* ?
                           Even if the test
                         result is < 4 pCi/L,*
                           consider testing
                         again sometime in
                            the future.
                        Remedial Action

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    In certain instances, such as may occur when measurements are performed in
different-seasons or under different weather conditions, the initial and follow-up tests
may vary by a considerable amount.  Radon levels can vary significantly between
seasons, so different values are to be expected.  The average of the two short-term
test results can be used to determine the need for remedial action.

    The testing strategy policies presented here allow homeowners to decide on the
need for mitigation with a high level of confidence that their decision is correct (EPA
400-R-92-011; U.S.  EPA 1992g).

2.2 MEASUREMENT LOCATION

    Short-term or long-term measurements should  be made in the lowest lived-in
level of the house.  The following criteria should be used to select the location of the
detectors within a room on this level:

      ii   The measurements should be made in the lowest level which contains
          a room that is used regularly. Test areas include family rooms, living
          rooms, dens, playrooms, and bedrooms. A bedroom on the lower
          level may be a good choice, because most people generally spend
          more time in their bedrooms than in any other room in the house
          (Chapin  1974, Moeller and Underhill 1976, Szalai 1972). If there are
          children  in the home, it may be appropriate to measure the radon
          concentration in their bedrooms or in other areas where they spend a
          lot of time, such as a playroom, that are situated in the lowest levels of
          the home.

      •   In general, measurements should not be made in kitchens, laundry
          rooms, or bathrooms. The measurements should  not be made in a
          kitchen because of the likelihood that an exhaust fan system and
          changes in small, airborne particles (caused by cooking) may affect
          the stability of WL measurements.  Measurements  should not be made
          in a bathroom because relatively little time is spent in a bathroom,
          because high humidities may affect the sensitivity of some detectors,
          and because of the likelihood that use of a fan may temporarily alter
          radon or decay product levels.

          Although radon in water may be a contributor to the concentration of
          airborne radon, radon in air should be measured before any diagnostic
          radon-in-water measurements are made. (Diagnostic measurements may
          be made in the bathroom; however, such diagnostic  measurements should
          not be used to determine the need for mitigation.)
                                        2-3

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       •  A position should be selected where the detector will not be disturbed
          during the measurement period and where there is adequate room for the
          device.

       •  The measurement should not be made near drafts caused by heating,
          ventilating and air conditioning vents, doors, fans, and windows.  Locations
          near heat, such as on appliances, near fireplaces or in direct sunlight, and
          areas of high humidity should be avoided.

       •  Because some detectors are sensitive to increased air motion, fans should
          not be operated in the test area. Forced air heating or cooling systems
          should not have the fan operating continuously unless it is a permanent
          setting.

       •  The measurement location should not be within 90 centimeters (three
          feet) of the doors and windows or other potential openings to the
          outdoors. If there are no doors or windows to the outdoors, the
          measurement should not be within 30 centimeters (one foot) of the
          exterior wall  of the building.

       •  The detector should be at least 50 centimeters (20 inches) from the floor,
          and at least  10 centimeters (four inches) from other objects. For  those
          detectors that may be suspended, an  optimal height is in the general
          breathing zone, such as two to 2.5 meters (about six to eight feet) from the
          floor.

    Sound judgement is required as to what space actually constitutes a room.
Measurements made in closets, cupboards, sumps, crawl spaces, or nooks  within the
foundation should not be used as a representative measurement.

2.3 INITIAL MEASUREMENTS

2.3.1 Rationale

    EPA recommends that a homeowner assessing the need for mitigation should first
make a short-term test.  Short-term measurements can be simple, produce results
quickly, and  allow the public to make decisions about radon reduction that are
cost-effective and protective of human health.

    The duration of short-term measurements can range from 48 hours to 90 days,
depending upon the method used.
                                     2-4


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2.3.2 Closed-Building Conditions

    Short-term measurements lasting between two and 90 days should be made
under closed-building conditions.  Closed-building conditions are necessary for
short-term measurements in order to stabilize the radon and radon decay product
concentrations and increase the reproducibilrty of the measurement.  Windows on a||
levels and external doors should be kept closed (except during normal entry and exit)
during the measurement period.  Normal entry and exit include a brief opening and
closing of a door, but--to the extent possible-external doors should not be left open
for more than a few minutes. In addition, external-internal air exchange systems (other
than a furnace) such as high-volume, whole-house and window fans should not be
operating.  However, attic fans intended to control attic and not whole building
temperature or humidity should continue to operate. Combustion or make-up air
supplies must  not be closed.

    In addition to maintaining closed-building conditions during the measurement,
closed-building conditions for 12 hours prior to the initiation of the measurement are a
required condition for measurements lasting less than four days, and are
recommended prior to measurements lasting up to a week in duration. Normal
operation of permanently installed energy recovery ventilators (also known as heat
recovery ventilators or air-to-air heat exchangers) may also continue during
closed-building conditions. In houses where permanent radon mitigation systems
have been installed, these systems should be functioning during the measurement
period.

    Closed-building conditions will generally exist as normal living conditions in
northern areas of the country when the average daily temperature is low enough so
that windows are kept closed. Depending on the geographical area, this can be the
period from late fall to early spring. In some houses, the most stable radon levels
occur during late fall and early spring, when windows are kept closed but the house
heating system (which causes some ventilation and circulation) is not used.  Available
information about variations of indoor radon levels in a particular area can be used to
choose a measurement time  when the radon concentrations are most stable.

    It may be  necessary, however, to make measurements during mild weather, when
closed-building conditions are not the normal living conditions.  It will then be
necessary to establish some  more rigorous means to ensure that closed-building
conditions exist prior to and during the measurements.

    Those performing measurements in southern areas that do not experience
extended periods of cold weather should evaluate seasonal variations in living
conditions and identify if there are times of the year when  closed-building  conditions
normally exist.  Ideally, measurements should be conducted during those  times. The
closed-building conditions must be verified and maintained more riqorouslv when thev
                                      2-5

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 are not the normal living conditions.  Air conditioning systems that recycle interior air
 can be operated during the closed-building conditions when radon measurements are
 being made.  However, homeowners should be aware that any air circulation system
 can after the radon decay product concentration without significantly changing the
 radon concentration.

     Short-term tests lasting just two or three days should not be conducted during
 unusually severe storms or periods of unusually high winds.  Severe weather will affect
 the measurement results in several ways. First, a high wind will increase the variability
 of radon concentration because of wind-induced differences in air pressure between
 the building interior and exterior. Second, rapid changes in barometric pressure
 increase the chance of a large difference in the interior and exterior air pressures,
 consequently changing the rate of radon influx. Weather predictions available on local
 news stations can provide sufficient information to determine if these conditions are
 likely.  While unusual variations between  radon measurements may be due to weather
 or other effects, the measurement system should be checked for possible problems.

     During any short-term test,  closed-house conditions should be maintained as
 much as possible while the test is in progress.  In tests lasting less than four days (96
 hours), closed-house conditions should be maintained for at least 12 hours before
 starting the test.  In tests lasting between four and seven days, closed-house
 conditions should be maintained while the test is in progress;  while recommended,
 the 12 hour closed-house condition before the start of the is not required.  In tests
 lasting more than seven days and less than 90 days, closed-house conditions should
 be maintained as much  as possible while the test is in progress.

 2.3.3  Interpretation of Initial Measurement Results

    If the initial measurement result is less than 4 pCi/L, or 0.02 WL, follow-up
 measurements are probably not needed. There is a relatively low probability that
 mitigation is warranted if the result is less than 4 pCi/L or 0.02 WL (EPA 400-R-92-011;
 U.S. EPA 1992g). Even  if the measurement result is less than 4 pCi/L, or 0.02 WL,
 however, a homeowner may want to test again sometime in the future.  If the
 occupants' living patterns change or renovations are made to the home and they
 begin using a lower level (such as a basement) as a living area,  a new test
 should  be  conducted on that level.

    The average year-round residential indoor radon level is estimated to be about 1.3
 pCi/L, and about 0.4 pCi/L of radon is normally found in outside air.  The U.S.
 Congress has set a long-term goal that indoor radon levels be no more than outdoor
 levels.  There is some risk of lung cancer from radon levels below 4  pCi/L,  and EPA
 recommends that the homeowner consider reducing the radon level if the average of
the first  and second short-term measurements or if a long-term follow-up
measurement is between 2 and 4 pCi/L (0.01 and 0.02 WL). While it is not yet
                                      2-6

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technologically achievable for all homes to have their radon levels reduced to outdoor
levels, the radon levels in some homes today can be reduced to 2 pCi/L or below.

    If the result of the short-term measurement is equal to or greater than 4 pCi/L, or
0.02 WL, the occupant should conduct a follow-up measurement using a short-term or
long-term test, as described in Section 2.4.

2.4 FOLLOW-UP MEASUREMENTS

2.4.1   Rationale

    The purpose of a follow-up measurement is to provide the homeowner with
enough information to make an informed decision on whether to mitigate to reduce
radon levels. The follow-up measurement, whether it is short-term or long-term,
provides an additional piece of information to confirm that radon levels are high
enough to warrant mitigation.  There are two major reasons why a second
measurement is necessary. First and most important, radon levels fluctuate over time
(see Section 1), and a second short-term measurement, when averaged with the first
test result, will provide a more representative value for the average radon level during
the period of the test, if a long-term follow-up measurement is conducted, that result
should provide an even more representative value for the long-term average radon
concentration. The second reason for making a follow-up measurement prior to
mitigation is that there is a small chance of laboratory or technician error in all
measurements, including radon measurements, and  a second test will serve as a
check on the first.

    Homes tested using the protocol in this section should not be mitigated on the
basis of a single short-term test.  A follow-up test is necessary for mitigation decision-
making regardless of the initial test result.

2.4.2   Short-Term and Long-Term Follow-Up Testing

    Follow-up testing should be conducted in the same location as the first
measurement (see Section 2.2).

    A follow-up test can be conducted with either a short-term or long-term
measurement device.  Long-term tests (> 90 days) will produce a reading that is more
likely to represent the home's year-round average radon level than a short-term test.
However, if the initial test result is high (for example,  greater than about 10 pCi/L, or
0.05 WL) or  if results are needed quickly, EPA recommends a second short-term test.
This will allow the homeowners to obtain information  necessary to decide quickly on
the need for mitigation. If the result of the initial measurement is between 4 pCi/L and
10 pCi/L (or between 0.02 WL and 0.05 WL), then either a short-term or long-term test
can be taken.
                                     2-7

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    If the long-term follow-up test result is 4 pCi/L, or 0.02 WL, or higher, then EPA
recommends remedial action.  Likewise, if the average of the initial and second
short-term results is equal to or greater than 4 pCi/L, or 0.02 WL, radon mitigation is
recommended. These recommendations are summarized in Exhibit 2-1.

    As with the initial short-term test, the second short-term test should be conducted
under closed-building conditions (Section 2.3.2). These conditions, however, are not
necessary for long-term tests (those lasting longer than 90 days).
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         Section 3:  DISCUSSION OF GUIDELINES PRESENTED IN THE
               HOME BUYER'S AND SELLER'S GUIDE TO RADON

3.1 INTRODUCTION

    The unique nature of a real estate transaction, involving multiple parties and
financial interests, presents radon measurement issues not encountered in non-real
estate testing.  EPA's objectives for issuing recommended protocols for radon
measurements made for real estate transactions are intended to reduce
misunderstanding and protect public health in several ways. First, EPA seeks to
provide home buyers, sellers, real estate agents, and testing organizations with a
common basis of understanding of the recommended procedures for radon
measurements. Second, the widespread implementation of this guidance will produce
results that are reliable indicators of the need for mitigation. A significant proportion of
radon measurements are conducted as part of real estate transactions, and all
aspects of these transactions are carefuHy scrutinized, so specific guidance from EPA
can help to ensure good quality measurements. When the results are interpreted
properly  and the appropriate remedial action is taken, these protocols will assist the
buyer and seller in reducing the risk to the occupants from radon exposure. The
availability of a nationally-recognized protocol for measurement and for the
interpretation of the measurement results will greatly assist home buyers, sellers, real
estate agents, builders, lenders, and radon measurement experts.

    These protocols are designed for use in residences, as described in the EPA
document, Home Buyer's and Seller's Guide to Radon (EPA 402-R-93-003; U.S. EPA
1993).  While that document offers general information on radon and testing, this
report presents a more technical description of EPA recommendations, including
discussion of guidelines for the interpretation of measurement results. As with all of
EPA's policies regarding radon measurements, these guidelines have been developed
after review and assistance from the radon measurement community and EPA's
Science Advisory Board. Technical information on a variety of radon measurement
methods is available in the EPA report titled Indoor Radon and Radon Decay Product
Measurement Device Protocols (EPA 520-402-R-92-004; EPA 1992c; these and other
EPA publications are available from the U.S. Government Printing Office [see Exhibit 1-
1], or your State or Regional EPA radon office, see Appendix A).

    The  radon testing guidelines in the Home Buyer's and Seller's Guide to Radon
have been developed specifically to deal with the time-sensitive nature of home
purchases and sales.  These guidelines are somewhat different from the guidelines in
other EPA publications, such as the 1992 Citizen's Guide to Radon (EPA 402-K-92-
001; U.S. EPA 1992a), which provide radon testing and reduction information for non-
real estate situations.

    There are also guidelines  in the Home Buyer's and Seller's Guide to Radon to
deal with the potential for radon test interference.  There are approaches that can  be
used to increase confidence in measurement results by detecting measurement
interference. For example, a device that offers a variety of ways to detect tampering

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 may serve to deter, as well as detect, interference with the device's operation or with
 proper closed-building measurement conditions.  Potential tampering indicators
 Include the ability of a device to record changes in radon levels, temperature, and
 humidity, or to detect movement of or around the device during the measurement.
 Refer to Section 3.5 for information and recommendations for interference-resistant
 testing.

      EPA investigated a variety of options for real estate testing.  EPA recommends
 testing in advance of putting the house on the-market. A long-term test, which is
 conducted for longer than 90 days, gives the most representative indication of the
 annual average radon concentrations in a home.  However,.for time-sensitive real
 estate transactions, the Home Buyer's Guide offers three short-term testing options.
 Short-term tests are conducted from two days to 90 days, depending on the
 measurement device.  Based on extensive quantitative analyses to evaluate the
 frequency with which long-term and short-term testing results lead to the same
 mitigation decision, EPA and its independent Science Advisory Board concluded that
 short-term tests can be used to assess whether a home should be remediated.

     The reliability of each radon measurement made for a real estate transaction, or
 for any purpose, is highly dependent upon the existence and documentation of an
 adequate quality assurance program implemented by both the tester and the analysis
 laboratory.  All the parties involved  in the real estate transaction depend upon the
 testers doing their job. This includes ensuring that the measurements are valid via the
 performance of quality control measurements and activities, and detecting
 measurement interference. The protocols outlined in this section were developed by
 EPA for testers and homeowners adhering to the quality assurance practices
 summarized in Section 4.4 of this report, and in EPA's Indoor Radon and Radon
 Decay Product Measurement Device Protocols (EPA 520-402-R-92-004- U S EPA
 1992c).

     Three options were determined to  be  satisfactory and are described here. The
 availability of three options will allow flexibility on the part of the party purchasing the
 test. Each of these options will produce results that can be used  to determine the
 need for mitigation.

     Both Options 1 and 2 require the use  of two measurements made for similar
 durations. Both  measurements should report results in units of pCi/L or both in WL
 Similar durations means that the two measurements must be made for a similar time
 period, with a two-hour grace period.  Specific information on measurement methods
 (listed in Exhibit 3-1) can be found in EPA's Indoor Radon and Radon Decay Product
Measurement Device Protocols (EPA 520-402-R-92-004; U.S. EPA 1992c).
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                                 Exhibit 3-1
                Radon and Radon Decay Product Measurement
                              Method Categories
                  A (DCi/Ll
    AC  Activated charcoal adsorption
integrating
    AT  Alpha track detection
    LS  Charcoal liquid scintillation

    CR  Continuous radon monitoring
    PB  Pump-collapsible bag
    SC  Evacuated scintillation cell
         (three-day integrating)
    EL  Electret ion chamber: long-term
    ES  Electret ion chamber: short-term
    UT  Unfiltered track detection
           B
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  3.2  OPTIONS FOR REAL ESTATE TESTING

  3.2.1    Option 1; Sequential Testing

      Sequential tests should be conducted under conditions that are as similar as
  possible, in the same location, and using similar devices and durations.  Both should
  produce results in the same units (pCi/L or WL). That is, both methods should be
  from column A or both from column B of Exhibit 3-1. Any EPA-recognized method
  may be used.  In addition, the results of the first test should not be reported prior to
  making the second measurement: both measurements should be reported at the
  same time in order to discourage tampering that may occur if the first test is known to
  be greater than 4 pCi/L or 0.02 WL  Note that measuring with different methods (e.g.,
  with AC and ES) may increase the potential for differences (e.g., measurement bias)
  between the results.  The results of both measurements should be reported, and the
  average of the two results should be used to determine the need for mitigation.  There
 will be some variation between the two results, which may be caused by the radon
 levels fluctuating in response to weather or other factors. If the variation is unusually
 large, it may be due to weather or other effects, but the measurement system should
 be checked for possible problems.

 3.2.2    Option 2: Simultaneous Testing

     This option involves the use of two tests, conducted simultaneously and side-by-
 side, made for similar durations, and producing results in the same units (i.e., both
 methods should be from column A or both should be from  column B of Exhibit 3-1).
 Any EPA-recognized method may be used. As with Option 1, using different methods
 for the two measurements (for example, ES and LS) may increase the potential for
 differences between the two results.  The two test results should be averaged to
 determine the need for remedial action.  The collocated devices should be placed four
 inches (10 centimeters) apart.

     Because radon  measurements,  like any measurements, usually  do not produce
 exactly the same results, even for simultaneous testing, there will usually be a
 difference between the two results. EPA offers the following guidance to testers for
 judging when two simultaneous, side-by-side measurements disagree to such an
 extent that two  additional measurements should be  performed.

    The results of the simultaneous measurements will fall into one of the three
 categories discussed below and illustrated in Exhibit 3-2.

 3.2.2.1  Both Measurement  Results Equal To or Greater Than
        4 pCI/L for 0.02 WL)

    In this case, the  average of the two results will  be equal to or greater than 4
pCi/L, or 0.02 WL, and mitigation is recommended.  The tester should report both
measurement results  as well as the average of the two results.
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                       Exhibit 3-2

Deciding on a Retest When Measurements Vary Significantly
                                  •  — 3
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                                    I?ง
                                 "11NP   18*
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3.2.2.2  Both Measurement Results Less Than A pCl/L for 0.02 WL1

     In this case, the average of the two measurements will be less than 4 pCi/L, or
0.02 WL, and both measurement results and the average result should be reported to
the client.

3.2.2.3  One Measurement Result Greater Than 4 oCl/L tor 0.02 WU. and
        One Measurement Result Leas Than 4 pCl/L tor 0.02 WU

     This is a special situation in which the average of the results is critical.  To assist
testers in ensuring that the difference between two measurements is small enough so
that clients may have confidence in, and understand, the results, EPA offers the
following simple guidance.

     If the higher result is twice or more the lower result, then the two results are not
within a factor of two, and a retest should be conducted. Section 3.2.2.5 provides
language for informing the client that a retest is warranted.

     If the higher result is less than twice the lower result, then the two results are
within a factor of two, and a retest is not necessary.  The results of both
measurements and the average of the two results should be reported to the client.
(See Section 4 for more detailed information on quality assurance and quality control
procedures.)

3.2.2.4  Precision Recommendations

     Measurements near the lower limit of detection (LLD) for the measurement
system  often have large and varying precision errors, and it is difficult to assign any
sort of probability level to very low results.

     Simultaneous measurement results that are-equal to-4-pCi/L, or 0.02 WL, or
greater should, however, exhibit some agreement. An example control chart for the
precision that may be expected is shown as Exhibit B-2 in Appendix B, which was
constructed using an average relative percent difference of 14 percent.  (Relative
percent difference is defined as the difference divided by the average.)  Using Exhibit
B-2, a relative percent difference greater than 36 percent should be observed less
than one percent of the time. Based upon this, EPA recommends that any side-by-
side, simultaneous measurements with results greater than or equal to 4 pCi/L, or 0.02
WL, and which exhibit a relative percent difference greater than 36 percent, be cause
for informing the client that the two results do not show good agreement. However,
since both results are greater than 4 pCi/L, or 0.02 WL, EPA recommends mitigation in
this case.  Testers should investigate the source of the error (see Appendix B).

     Results between 2 pCi/L (or 0.01 WL) and 4 pCi/L (or 0.02 WL), should also
exhibit some agreement. The level of agreement expected should be based upon the
tester's experience with duplicate measurements made with that technique in this
-range of radon concentrations.  An example control chart for the precision that may

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  be expected in this region is shown as Exhibit B-3 in Appendix B, which was
  constructed using an average relative percent difference of 25 percent. Using this
  chart, a relative percent difference between duplicates greater than 67 percent should
  be observed less than one percent of the time.  Based upon this, EPA recommends
  that any side-by-side, simultaneous measurements with  results less than 4 pCi/L or
  0.02 WL, and which exhibit a relative percent difference  greater than 67 percent 'be
  cause for informing the client that the two results do not show good agreement' but
  that both are less than 4 pCi/L, or 0.02 WL, and therefore mitigation is not
  recommended. Testers should investigate the source of the error (see Appendix B).

  3.2.2.5  Recommended Language for Informing the Client that a Retest is
         Warranted
      If a retest is warranted (see Section 3.2.2.3), EPA recommends that the tester
 inform the client that EPA provides guidance for how well two measurements should
 agree, that the measurements performed fall outside the range, and that a retest
 should be conducted. A retest should consist of measurements performed according
 to one of the protocols outlined in Sections 3.2.1, 3.2.2, or 3.2.3.

 3.2.3   Option 3: Single Test Option

      This option requires an active continuous monitor (method CR or CW) that has
 the capability to integrate and record a new result at least hourly.  Shorter integration
 periods  and  more frequent data logging afford greater ability to detect unusual
 variations in  radon or radon decay product concentrations.  The minimum
 measurement period is 48 hours.  The first four hours  of data from a continuous
 monitor  may be discarded or incorporated into the result using system correction
 factors (EPA 520-402-R-92-004; EPA 1992c). There must be at least 44 contiguous
 hours of usable data to produce a valid average.  (The "backing out" of data [i e
 removal  of portions imbedded in the two days] to account for weather or other "
 phenomena will invalidate the measurement.) The periodic results should be
 averaged to produce a result that is reported to the client.

     If the monitor cannot  integrate over a period of one hour or less, then an
 additional (secondary)  passive or active measurement  device must be used  The
 second measurement, which may be made with a passive or active device can be
 used  simultaneously or sequentially, as discussed in Options 1 and 2 (Sections 321
 and 3.2.2). If the two measurements are performed simultaneously, their results
 should be evaluated following the guidance in Section  3.2.2.  If the two measurements
 were performed sequentially, it can  be expected that the two results will be different
 As discussed in Section 3.2.1, the difference between sequential tests may be due to
 radon levels fluctuating in response to weather or other factors.

    In general, confidence in a radon measurement can be increased by performing
another measurement with  a second measurement device.  However, there are other
approaches or features that can be used to increase the confidence of a
measurement result obtained using  active monitor devices.  These approaches include

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the use of device self-diagnostic features, and data validation or verification
procedures, that could be employed before and/or after the measurement. Examples
of such approaches are the use of check sources before and after each
measurement, and the use of spectrum readouts.  These capabilities are examples,
and different technologies may be able to perform other similar self-diagnostic or
quality assurance checks.  Other features that increase the confidence of a single
active test include (but are not limited to) the ability to check air flow rates and voltage
meters before and after each measurement.  Measurement companies should
incorporate such checks into their routine instrument performance checks as part of
their standard operating procedures.

     Additional features that can increase confidence in measurement results are
those that detect measurement interference; these features are discussed in Section
3.5. For example,  a device that offers a variety of ways to detect tampering may serve
to deter, as well  as detect, interference with the device's operation or with proper
closed-building measurement conditions. Potential tampering indicators include the
ability of a device to record changes in temperature, humidity,  or movement of or
around the device  during the measurement.

         Instruments with greater efficiency or sensitivity, or a high signal-to-noise ratio
(see Glossary for definitions of these terms), can achieve results with a smaller
uncertainty than  instruments with low efficiency, poor sensitivity, or low signal-to-noise
ratio. Greater efficiencies,  sensitivities, or a high signal-to-noise ratio may also facilitate
tampering detection by being more sensitive to fluctuations in radon levels.  There
have been recommendations for setting minimum efficiency standards for active
devices at 16 counts per hour per pCi/L EPA plans to conduct research to establish
minimum standards in the future for all categories of devices, passive as well as active
detectors.  The reliability of any type of equipment, however, needs to be established
and documented via a complete quality assurance program.  This includes routine
instrument performance checks prior to and after each measurement, annual
calibrations, semi-annual instrument cross-checks, the performance  of duplicate
measurements in 10 percent of the measurement locations, and frequent background
and spiked measurements.

3.3 MEASUREMENT LOCATION

     EPA recommends that measurements made for a real estate transaction be
performed in the lowest level of the home which is currently suitable for
occupancy.  This  means the lowest level that is currently lived-in, or a lower level that
is not currently used (such as a basement, which a buyer could use for living space
without renovations).  Measurements should be made in a room that is used regularly,
such as a living  room, playroom, den, or bedroom. This includes a basement that can
be used as a recreation room, bedroom, or playroom.  This provides the buyer with
the option of using a lower level of the home as part of the living area, with the
knowledge that  it has been tested for radon.
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3.4  MEASUREMENT CHECKLIST

     EPA presents the following checklist to help ensure that a radon measurement
conducted for a real estate transaction is done properly. The seller, or an EPA-listed
or State-listed tester, should be able to confirm that all the items in this checklist have
been followed.  If the tester cannot confirm this, another test should be made.

     Before the radon test:

     •  Notify occupants of the importance of proper testing conditions. Give
        occupants written instructions or a copy of the EPA Home Buyer's and
        Seller's Guide to Radon (EPA 402-R-93-003; U.S. EPA 1993), or a State-
        required alternative, and explain the directions carefully.

     •  The radon measurement service and device used should be listed by EPA's
        National Radon Measurement Proficiency (RMP) Program  (EPA 520/1-91-006-
        U.S.  EPA 1991) or listed by your State. Follow the manufacturer's
        instructions that come with the device.

     •  If a testing professional  conducts the test, only EPA-listed or State-listed
        individuals should be  hired. Their photo identification should be provided to
        the client or homeowner at the time of, or before, the test,  and the
        contractor's identification number should be clearly visible  on the test report.

    •   The test should include method(s) to prevent or detect interference with
        testing conditions or with the testing device itself.

    •   Conduct the radon test for a minimum of 48 hours.  Some devices must be
        exposed for longer than the 48-hour minimum.

    •   In homes with  an  active  radon reduction system, check that the fan is
        running at least 24 hours before starting a short-term test lasting less than
       four days.  Air exhaust equipment, like radon reduction system fans and
       small  exhaust fans that typically operate for short periods (e.g., bathroom
       fan) may be used during the test.

    •  EPA recommends that short-term radon testing, which lasts for no more than
       a week in length, be done under closed-building conditions.  Closed-building
       conditions means  keeping all windows closed, keeping doors closed except
       for normal entry and exit, and  not operating fans or other machines that bring
       in air from outside. Note that fans that are part of a radon  reduction  system
       or small exhaust fans operating for only short periods of time may run durina
       the test.                                                              a
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    •  When doing short-term testing lasting less than four days, ft is Important to
        maintain closed-building conditions for at least 12 hours before the beginning
        of the test and for the entire test period. Do not operate fans or other
        machines that bring in air from the outside.

    During the radon test:

    •  Maintain closed-building conditions during the entire time of a short-term test,
        especially for tests shorter than one week in length.

    •  Operate the home's heating and cooling systems normally during the test.
        For tests lasting less than one week, only operate air conditioning units that
        recirculate interior air.

    •  Do not disturb the test device at any time during the test.

    •  If a radon reduction system is in place, make sure the system is working
        properly and will be in operation during the entire radon test.

    After a radon test:

    •  If a high radon level is confirmed, fix the home.  Pages 21 to 23 of'EPA's
        Home Buyer's and Seller's Guide to Radon (EPA 402-R-93-003; U.S. EPA
        1993) recommend the next steps that should be taken,  such as contacting a
        qualified radon reduction contractor to  lower the home's radon level.

    •  The radon tester or homeowner should be able to verify or provide
        documentation asserting that testing conditions were not violated during the
        testing period.

3.5 INTERFERENCE-RESISTANT TESTING

    EPA strongly encourages the use of radon testing devices with interference-
resistant features inherent in, or associated with, the device.

    Interference with a radon measurement is defined as the altering of test
conditions prior to or during the measurement to either change the radon or decay
product concentrations or alter the performance of the measurement equipment. The
following discussion reviews some of the types of test interferences and methods of
detecting and preventing such  interferences.
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      Test interference typically causes measurement results to be different than if all
 proper test conditions were maintained.  False low results have been primarily
 associated with testing during a real estate transaction, although they also happen
 when the occupants of the dwelling are not properly informed about the necessary
 test conditions. Test interference can also inadvertentJy increase measurement results,
 although the intent is generally to lower the results.

     The current occupant may have an interest in the test results being as low as
 possible to avoid hindering the sale of the dwelling or incurring the added expense of
 having to install a mitigation system. The potential for test interference puts the
 professional radon tester into the position of verifying that the equipment and the
 required test conditions have been maintained. A measurement result that is below
 the action guideline may be suspect if the tester cannot verify that the necessary test
 conditions were maintained.

     If the tester arrives at a  property and finds windows or doors open, or suspects
 that closed-building conditions were not maintained for 12 hours prior to arrival, then
 the tester should extend the test period to account for this condition.

 3.5.1    influencing Test Area Concentration

     The primary method of temporarily reducing radon levels is to ventilate the test
 area with outdoor air.  Ventilation will slow down radon entry by both reducing
 negative pressure in the test  area and by diluting the reduced radon concentration.
 Even small openings of a single window in the test area can have a large effect.
 Ventilating the floors above the test area has significantly  less effect, unless the test
 area is connected with the ventilated room (s) by an operating central air handling
 system.

     Radon decay product levels are sensitive  to air movement.  As air movement
 increases, decay products will plate out on walls and other surfaces, including fans,   :
thereby reducing airborne decay product concentrations.  Decay products will be
further reduced if the fan also includes a filter.  Radon levels are, however, not affected
by filtering or air movement.

     It is also possible to alter concentrations in a tight room if the heating system is
operating in an abnormal fashion. Since this may not be the typical operation of the
system, it is, in effect, interfering with normal house conditions.

     It is important to recognize that test interference  can  increase radon or decay
product levels, despite intent to lower the results.
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3.5.2    Equipment Interference

     The primary method of interfering with testing equipment is to move the detector
to an area of low radon concentration.  Other types of interference vary in their ability
to influence different types of detectors.  For example, interfering with the air sampling
mechanisms can maintain the radon concentration at the time of interference, or cause
a large decrease in the reported concentration.  Similarly, covering a decay product or
charcoal detector could cause a large drop in the reported values, while other types of
radon detectors would only show a reduced response time to changes in the test area
level. In addition, charcoal detectors are sensitive to heat.  Some active radon
monitors and open face charcoal canisters are also sensitive to high humidity.  Any
detector that yields a single result could be turned off or sealed in its container or lid
during most of its exposure period.

3.5.3    Preventing Interference

     EPA recommends that a radon measurement conducted for a real estate
transaction be performed using tamper-resistant testing techniques. It is more
advantageous for the tester to take steps to prevent interference rather than to simply
detect ft.  Preventing interference can best be accomplished by:

     •   Educating the parties to a real estate transaction about the necessary test
         conditions.

     •   Including in the standard documentation for each measurement an
         agreement signed by the  parties involved in the real estate transaction listing
         the necessary test conditions and their agreement not to interfere with the
         conditions.

         The agreement should also state .that the tester, in their discretion may nullify
         the test results if ft appears that, in their professional judgement, the test
         results were rendered unreliable.

     •   Informing the parties that  interference with the test conditions may increase
         the radon levels.

     •   Informing the parties that  the tester is using interference-detecting
         techniques.and that these allow the detection and documentation of test
         interference.
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3.5.4   Interference-Resistant Detectors

     The following is a partial list of common equipment and measures that can serve
to prevent and/or detect test interference. There may be other methods available.
Equipment that offers a combination of tamper-detecting features also offers a greater
chance of detecting interference.

     •  The ability to integrate and record frequent radon measurements over short
        intervals (an hour or less) is an important tamper detection feature.
        Continuous (active) monitors that provide frequent measurements can
        indicate unusual concentration changes that can be indicators of test
        interference.

     •  Measuring  other parameters may provide additional indicators of test
        interference, such as a detector tilt indicator or a continuous recording of
        pump flow rate.

     •  A motion indicator can also indicate when the detector was approached or
        moved.

     ซ  A simultaneous, several-day continuous measurement of both radon and
        decay product concentrations will produce  a series of equilibrium ratio
        values. These values can be inspected for unusual swings or abnormal
        levels, possibly indicating interference.

     •  Measurement of CO2 levels can indicate changes in the test area infiltration
        rate of outdoor air.

     ซ  The performance of a grab radon measurement, a grab decay product
        measurement, or both, before and after a longer-term measurement can offer
        useful information.  For example, the initial and final concentrations and
        equilibrium ratios can be compared for consistency.  Note:  The results of
        measurements lasting less than 48 hours (e.g., grab samples) should not be
        used  as the basis for deciding to fix a home.

     ซ  Frequent temperature readings may help to indicate changes in the test area
        infiltration rate of outdoor air.

     ป  Humidity (as well as temperature) recordings can be especially helpful in
        identifying potential unusual changes  in test conditions that occur during the
        test period.

     •  Instruments that do not allow occupants to  view preliminary results (via a
        visible printer or screen) may reduce occupants' interference.
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 Placement indicators can also indicate if a detector has been tampered with
 or moved. The position of the detector should be noted so that, upon
 retrieval, any handling of the detector can be indicated by a change in its
 position. A detector may be hung or placed slightly over the edge of its
 support to discourage covering it. Passive detectors may be hung or
 suspended in a radon-permeable bag that uses a strap and seal to prevent
 removing or covering it.  Cages can be equipped with a movement indicator
 to deter handling of the cage or the detector within it.

 Seals can aid in detecting and discouraging test interference, and they are
 especially important in the absence of other tamper detection measures.
 Non-sealable caulks and/or tapes can be used to verify that detectors have
 not been altered or moved, or that windows or non-primary exterior doors
 have not been opened.  Seals alone will not prevent excessive ventilation
 through primary doors.

 Seals should be placed on the lowest operable windows and  non-primary
 exterior doors, as well as between the detector and its support and any other
 components of the detector that could be tampered with.  It may be
 advisable to place a seal on the furnace control fan switch. It may also be
 necessary to attach to the caulk seal  something fragile that protrudes out, to
 indicate any  handling or covering of the detector.

 A number of different products or combination of products can be used for
 tamper seals. For a seal to be effective, it needs at least the following unique
 qualities.

 • The seal must adhere readily to a multitude of surfaces, and yet be easily
   removed without marring the surface.

 • It needs to be non-resealable or show evidence of disturbances

 • It must be unique enough to prevent easy duplication.

 • It should be visible enough to discourage tampering.

The tamper resistance of the seal can be increased by using a caulk over the
seal edges or by slicing a large portion of the center of the seal to ensure the
seal is broken in case of tampering.

Most paper or plastic tapes and caulks have only some of these qualities.
There are, however, a number of seals manufactured specifically for radon
testing. It would be advisable to use one of these products and follow the
manufacturer's installation recommendations.  The best caulking to use as a
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        seal is a removable weatherstripping caulk. This type of caulking adheres
        readily to most surfaces, yet comes off easily without leaving a mark or being
        resealable.

     Upon retrieval of the detector, the tester should carefully inspect the following:

     •  That all closed-building conditions are still being maintained;
     ii  Any changes in the detector placement;
     n  The condition of all seals; and
     •  Any abnormal variations in any of the measurements made.

This information should be recorded, as described in Section 4.3.5.
                                      3-15

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 4.1
     Section 4: GENERAL PROCEDURAL RECOMMENDATIONS

INTRODUCTION
      This section outlines basic procedural recommendations for anyone involved in
 the measurement of radon in homes for both real estate and non-real estate related
 measurements.

 4.2   INITIAL CLIENT INTERVIEW

      Reasonable efforts should be made to determine whether the home is new
 and/or occupied, and who will be in charge of the home during the measurement
 period.  Testing organizations should inform the client and other parties to the real
 estate transaction of:

      •    The appropriate EPA testing recommendations as outlined in this report,
            the 1992 Citizen's Guide to Radon (EPA 402-K-92-001; U.S. EPA 1992a),
            or the Home Buyer's and Seller's Guide to Radon (EPA 402-R-93-003;
            U.S. EPA 1993); and

      •    The types of devices they will be using for that test, and EPA
            documentation indicating that the testing organization or individual is
            RMP-listed for that device.

 4.3   MEASUREMENT RECOMMENDATIONS

 4.3.1  Selecting a Measurement Approach

      The purpose of the measurements, as well as budget and time constraints,
 dictate the protocol used. Measurements made for the purpose of assessing the
 need for mitigation of one's own property should be made according to the guidance
 discussed in Section 2 of this document; Section 3 outlines options for protocols for
 measurements made for real estate transactions. Organizations that provide
 consultant services, or place or retrieve devices, should review the protocol options
 and the  clients' needs, and inform clients of the buildings and test period conditions
 necessary for conducting valid measurements. In some areas, companies may offer
 different types of radon  service agreements.  Some agreements allow for a one-time
fee that  covers both testing, and if needed, radon reduction.

      The organizations or individuals performing the measurement service should
 use only those specific devices or methods for which that organization or individual is
 listed according to the National RMP Program (EPA 520/1-91-006; U.S. EPA 1991).
Adherence to the EPA device protocols, Indoor Radon and Radon Decay Product
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Measurement Device Protocols (EPA 520-402-R-92-004; U.S. EPA 1992c) is a
requirement for participation in the RMP Program.

      4.3.2   Written Measurement Guidance

      Measurement organizations should provide clients with written measurement
instructions that clearly explain the responsibilities of the client and the other parties to
the real estate transaction during the test period.  Written and verbal guidance should
be in accordance with EPA's Indoor Radon and Radon Decay Product Measurement
Device Protocols  (EPA 520-402-R-92-004; U.S. EPA 1992c) and guidance published in
the RMP Program Handbook (EPA 520/1-91-006; U.S. EPA 1991). At a minimum, the
guidance should include the following elements:

      •    A statement of whether the device measures radon or radon decay
            products and a discussion of the units in which all results will be
            reported.

            The results of radon decay product measurements should be reported in
            working levels (WL).  If the WL value is converted to a radon
            concentration and is reported to the homeowner, it should be stated that
            this approximate conversion is based on a 50 percent equilibrium ratio
            (unless the actual equilibrium ratio is determined).  In addition, the report
            should indicate that this ratio is an assumed average found in the home
            environment; any indoor environment may have a different and varying
            relationship between radon and its decay products.

      •    A description of closed-building conditions and a stated requirement that
            these conditions be maintained 12 hours prior to and during all
            short-term measurements lasting less than four days and preferably for
            those lasting up to one week.

      •    Directions that the building's heating, ventilating, and air conditioning
            (HVAC) system and any existing mitigation system should be normally
            operated 24 hours prior to and during all measurements.

      •    A permanent radon reduction system should be fully operational for at
            least 24 hours  prior to testing to determine the mitigation system's
            effectiveness.  The mitigation system is to be operated  normally and
            continuously during the entire measurement period.

      ป     Specific information on the minimum and maximum duration of exposure
            for the measurement device(s).

      •     If the client will be performing the test, procedures for placing, retrieving,
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             and handling the device.

       •     A written non-interference agreement (see Sections 3.5.3 and 4.3.4) to
             be signed and returned by the parties to the real estate transaction
             which confirms that they followed all instructions and did not interfere
             with the conditions or the measurement device.

4.3.3  Conditions for a Valid Measurement

       Measurements should not be conducted if temporary radon reduction
measures have been implemented.  These include the introduction of unconditioned
air into the home or closure of normally accessible areas of the home.  In this case,
the measurement organization or individual should inform the client and other parties
to the real estate transaction that these conditions will invalidate measurement results
and decline to conduct a measurement until the conditions have been corrected.

       A permanent radon reduction system should be fully operational for at least 24
hours prior to testing to determine the mitigation system's effectiveness. The
mitigation system is to be operated normally and continuously during the entire
measurement period.

4.3.4  Non-interference Controls

       The measurement  organization should provide parties to a real estate
transaction with a written  statement that discusses the importance of proper
measurement conditions and of not interfering with the measurement device or
building conditions. The reader should refer to Section 3.5.3 for more information on
non-interference agreements.

       Organizations  that  place and retrieve devices should, in addition to providing
written guidance, take steps to identify attempts to  interfere with the measurement
device or building conditions.  There is increasing use of non-interference agreements
signed by parties involved in real estate transactions to help prevent interference with
the radon test and test conditions. The reader should refer to Section 3.5 for more
information on tamper-resistant testing.

      The signed non-interference agreement, a description of all non-interference
controls employed, and a statement addressing any observed breaches of the
non-interference agreement/controls should be made part of the permanent
measurement documentation for each measurement.
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4.3.5 Measurement Documentation

      Measurement organizations should record sufficient information on each
measurement in a permanent log to allow for future data comparisons, interpretations,
and reporting to clients.  EPA recommends that a measurement log be kept with the
following information and be maintained for five years. Additional method-specific
documentation is outlined in EPA's Indoor Radon and Radon Decay Product
Measurement Device Protocols (EPA 520-402-R-92-004; U.S. EPA 1992c).

      •     A copy of the final report, including the measurement results, and the
            statement outlining any recommendations concerning retesting or
            mitigation provided to the building occupant or agent.

      •     The address of the building measured, including zip code.

      •     The exact locations of all measurement devices  deployed.  It is advisable
            to diagram the test area, noting the exact location of the detector.

      •     Exact start and stop dates and time of the measurement period as
            required for analysis.

      •     A description of the device used, including its RMP device identification
            number and serial number if any.

      •     A description of the condition of any permanent vents, such as crawl
            spacf vents or combustion air supply to combustive appliances.

      ป     The name and RMP identification number (EPA 520/1-91-014-3N; U.S.
            EPA 1992e) of the serivce or analysis organizations used to analyze
            devices.

      •     The name and RMP identification number (or State license number) of
            the individual who conducted the test.

      ป     A description of any variations from or uncertainties about standard
            measurement procedures, closed-building conditions, or other factors
            that may affect the measurement result.

      •     A description of any non-interference controls used and copies of signed
            non-interference agreements.

      •     A record of any quality control measures associated with the test, such
            as results of simultaneous or secondary measurements.
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4.4   QUALITY ASSURANCE IN RADON TESTING

      Anyone providing measurement services using radon or radon decay product
measurement devices should establish and maintain a quality assurance program.
These programs should include written procedures for attaining quality assurance
objectives and a system for recording and monitoring the results of the quality
assurance measurements described below. EPA offers general guidance on
preparing quality assurance plans (QAMS-005/80; U.S. EPA 1980); a draft standard
prepared by a radon industry group is also available (AARST 1991). The quality
assurance program should include the maintenance of control charts and related
statistical data, as described by Goldin (Goldin 1984), by EPA (EPA 600/9-76-005; U.S.
EPA 1984), and in Appendix B of this document.

4.4.1  Calibration Measurements

      Calibration measurements are measurements made in a known radon
environment, such as a calibration chamber.  Detectors requiring analysis, such as
charcoal canisters, alpha track detectors, electret ion chambers, and radon  progeny
integrating samplers are exposed in a calibration chamber and then analyzed.
Instruments providing immediate results, such as continuous working level and radon
monitors, should be operated in  a chamber to establish individual instrument
calibration factors.

      Calibration measurements must be conducted to determine and verify the
conversion factors used to derive the concentration results. These factors are
determined normally for a range  of concentrations and exposure times, and for a
range of other exposure and/or analysis conditions pertinent to the  particular device.
Determination of these calibration factors is a necessary part of the  laboratory
analysis, and is the responsibility of the analysis laboratory. These calibration
measurement procedures, including the. frequency, of tests .and the number of devices
to be tested, should be specified in the quality assurance program maintained  by
manufacturers and analysis laboratories.

4.4.2 Known Exposure Measurements

      Known exposure measurements or spiked samples consist of detectors that
have been exposed to known concentrations in a radon calibration  chamber. These
detectors are labeled and submitted to the laboratory in the same manner as ordinary
samples to preclude special processing.  The results of these measurements are used
to monitor the accuracy of the entire measurement system. Suppliers and analysis
laboratories should provide for the blind introduction of spiked samples into their
measurement processes and the monitoring of the results in their quality assurance
programs. All organizations providing measurement services with passive
devices should conduct spiked measurements at a rate of three per 100
                                     4-5

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 measurements, with a minimum of three per year and a maximum required of six per
 month. Providers of measurements with active devices are required to recalibrate
 their instruments at ieast once every 12 months and perform cross-checks with RMP-
 listed devices at least once every six months.  Participation in EPA's National RMP
 Program will not satisfy the need for annual calibration, as this Program is a
 performance test, not a calibration procedure.

 4.4.3  Background Measurements

       Background measurements are required both for continuous monitors and for
 passive detectors requiring laboratory analysis. Users of continuous monitors must
 perform sufficient instrument background measurements to establish a reliable
 instrument background and to check on instrument operation. For more specific
 information on how often background measurements should be made, refer to EPA's
 Indoor Radon and Radon Decay Product Measurement Device Protocols (EPA 520-
 402-R-004; U.S. EPA 1992c).

       Passive detectors requiring laboratory analysis require one type of background
 measurement made in the laboratory and another in the field. Suppliers and analysis
 laboratories should measure routinely the background of a statistically significant
 number of unexposed detectors from each batch or lot to establish the laboratory
 background for the batch and the entire measurement system. This laboratory blank
 value is subtracted routinely (by the laboratory) from the field sample results reported
 to the  user, and should be made available to the users for quality assurance
 purposes.  In addition to these background measurements, the organization
 performing the measurements should calculate the lower limit of detection (LLD) for its
 measurement system (Altshuler and Pasternack 1963, ANS11989, U.S. DOE 1990).
 This LLD is based on the detector and analysis system's background and can restrict
 the ability of some measurement systems to measure low concentrations.

       Providers of passive detectors should employ field controls (called blanks)
 equal to approximately five percent of the detectors that are deployed, or 25 each
 month, whichever is smaller. These controls should be set aside from each detector
 shipment, kept sealed and in a low radon environment, labeled in the same manner as
the field samples to preclude special processing, and returned to the analysis
 laboratory along with each shipment.  These field blanks measure the background
exposure that may accumulate during shipment and storage, and the results should
be monitored and recorded. The recommended action to be taken if the
concentrations measured by one or more of the field blanks is significantly greater
than the LLD is dependent upon the type of detector.  More information is available in
EPA's Indoor Radon and Radon Decay Product Measurement Device Protocols (EPA
520-402-R-92-004; U.S. EPA 1992c).

                                     4-6

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 4.4.4  Duplicate Measurements

       Duplicate measurements provide a check on the quality of the measurement
 result, and allow the user to make an estimate of the relative precision.  Large
 precision errors may be caused by detector manufacture, and/or improper data
transcription or handling by suppliers, laboratories, or technicians performing
placements.  Precision error can be an important component of the overall error, so it
is important that all users monitor precision.

       Duplicate measurements for both active and passive detectors should be side-
by-side measurements made in at least 10 percent of the total number of
measurement locations, or 50 each month, whichever is smaller.  The locations
selected for duplication should be distributed systematically throughout the entire
population of samples. Groups providing measurement services to homeowners can
do this by providing two measurements, instead of one, to a random selection of
purchasers, with the measurements made side-by-side.  As with spiked samples
introduced into the system as blind measurements, the precision of duplicate
measurements should be monitored and recorded in the quality assurance records.
The analysis of data from duplicates should follow the methodology described in
Appendix B of this document. If the precision estimated by the user is not within the
precision expected of the measurement method, the problem should be reported to
the analysis laboratory and the cause investigated.

4.4.5  Routine  Instrument Performance Checks

       Proper functioning of analysis equipment and operator usage  require that the
equipment and  measurement system be subject to routine checks.  Regular
monitoring of equipment and operators is vital to ensure consistently accurate results.
Performance checks of analysis equipment includes the frequent use of an instrument
check  source. In addition, important components of the device (such as a pump and
pump flow rate, battery, or electronics)  should be checked prior to each measurement
and the results noted in a log. Each user should develop methods for regularly (daily,
or at least prior to each measurement) monitoring their measurement system, and for
recording and reviewing results.

4.4.6   Quality Assurance Plans

      All organizations should develop, implement, revise periodically, and maintain a
detailed quality assurance plan (GAP) appropriate to each device or method used.
This is  a requirement for participation in EPA's National Radon Measurement
Proficiency (RMP) Program. Specific guidance on the necessary quality control
measures for each measurement method is provided in EPA's Indoor Radon and
                                     4-7

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Radon Decay Product Measurement Device Protocols (EPA 520-402-R-92-004; U.S.
EPA 1992C).

      Organizations that do not use continuous monitors or do not analyze detectors
also need to write and follow a QAP, and conduct quality control measurements.
These include duplicate, blank, and spiked measurements as described in Section
4.4.   For further information on EPA's RMP Program, please contact:

                  RMP Program Information Service
                  Research Triangle Institute
                  3040 Cornwallis Road-Building 7
                  P.O. Box 12194
                  Research Triangle Park, NC 27709-2194
                  (919-541-7131/FAX -7386)

4.5   STANDARD OPERATING PROCEDURES

      Organizations performing radon measurements should have a written,
device-specific standard operating procedure  (SOP) in place for each radon
measurement system they use.  An SOP must include specific information describing
how to operate and/or analyze a particular measurement device.  Organizations that
analyze devices should develop their own SOP or adapt manufacturer-developed
SOPs for their devices. Organizations that receive results from a laboratory should
have a device-specific SOP for each brand/model/type of device that they use.  All
SOPs should be consistent with the appropriate protocol outlined in EPA's Indoor
Radon and Radon Decay Product Measurement Device Protocols (EPA 520-402-R-92-
004; U.S. EPA 1992c).

4.6   PROVIDING INFORMATION TO  CONSUMERS

      Organizations should provide the customer with the following information:

      •     Devices that will be placed by the customer must be accompanied by
            instructions on how to use the device. These instructions should be
            consistent with EPA's Indoor Radon and Radon Decay Product
            Measurement Device Protocols (EPA 520-402-R-92-004; U.S. EPA 1992c)
            and include specific information on the minimum and maximum length of
            time that the device must be exposed.

      •     The service organization should inform clients about sources of
            information on mitigation, such as EPA's Consumer's Guide to Radon
            Reduction (EPA 402-K-92-003; U.S. EPA 1992b),  and other information

                                       4-8

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            available through their State Radon office. The organizations should also
            provide any State-required brochures which provide information on
            mitigation.

      •     If service organizations distribute the Consumer's Guide brochure, it
            should be reproduced in its entirety.

4.7   REPORTING TEST RESULTS

      Organizations should return radon measurement results to clients within a few
weeks of retrieving exposed devices or receiving an exposed device which has been
delivered for analysis.  At a minimum, the client report should contain the following
information:

      •     Measurement results reported in the units that the device measures. Any
            measurement results based on radon gas (pCi/L of air) should be
            reported to no more than one decimal place, e.g., 4.3 pCi/L Any
            measurement result based on radon decay products (WL) should be
            reported to no more than three decimal places, e.g., 0.033 WL. Any
            conversions from WL to pCi/L or from pCi/L to WL should be presented
            and explained clearly.

            If the WL value is converted to a radon concentration, it should be stated
            in the report to the homeowner that this approximate conversion is
            based on a 50 percent equilibrium ratio (unless the  actual equilibrium
            ratio is determined). In addition, the report should indicate that this ratio
            is typical of the home environment, but that any indoor environment  may
            have a different and varying relationship between radon and its decay
            products.

      •     The dates of the  measurement period and address  of the building
            tested.

      •     A description of the device used, its manufacturer, model or type, and
            the device identification (serial) numbers.

      •     The name and RMP identification numbers of the organization and
            individual placing and retrieving the device and the organization
            analyzing the device, if they are different.

      •     A statement concerning any observed tampering or deviations from the
            required test conditions.

      •     Organizations that offer measurement services with grab sampling
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            devices should provide clients with written notification stating that grab
            sample results can be useful diagnostic tools, but should not be used for
            deciding whether or not to mitigate.

4.8   TEMPORARY RISK REDUCTION MEASURES

      Contractors should refer the occupants of the house and real estate agents to
EPA's Interim Radon Mitigation Standards (U.S. EPA  1992d) or the Consumer's Guide
to Radon Reduction (EPA 402-K-92-003; U.S. EPA 1992b) for information on
temporary and permanent risk reduction measures.

      If any radon reduction efforts are identified during measurement procedures,
testers should inform clients and other parties to the real estate transaction that
altered conditions during the measurement will invalidate the results and decline to
conduct a measurement until the conditions have been corrected.

4.9   RECOMMENDATIONS FOR MITIGATION

      The measurement organization should inform consumers that EPA
recommends fixing houses with radon levels equal to or greater than 4 pCi/L, and that
EPA recommends in its "Consumer's Guide to Radon Reduction" the use of EPA
Radon Contractor Proficiency (RCP)-listed and/or State-listed mitigation contractors to
perform the work (EPA 402-K-92-003; U.S. EPA 1992b).

      Organizations should refer customers to their State radon office for copies of
EPA's "Consumer's Guide to Radon Reduction" (EPA 402-K-92-003; U.S. EPA 1992b)
and a list of EPA RCP-proficient and State-listed mitigators.

      Homes should also be tested again after they are fixed to be sure that radon
levels have been reduced.  If the occupants' living patterns changes and they begin
occupying a lower level of their home (such as a basement), the home should be
retested on that level.  In addition, it is a good idea for homes to be retested
sometime in the future to be sure  radon levels remain low.

4.10  WORKER SAFETY

      Individuals and organizations should comply with all applicable Occupational
Safety and Health Administration (OSHA) standards and guidelines relating to
occupational worker exposure, health, and safety. Information on worker health and
safety contained in EPA or State publications is not considered a substitute for any
provisions of the Occupational Safety and Health Act  of 1970 or for any standards
issued by OSHA.
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                                APPENDIX A
                 STATE AND EPA REGIONAL RADON OFFICES

 A.1    STATE RADIATION AND RADON OFFICES

       The State radiation and radon offices distribute EPA's radon-related technical
 and guidance documents.      ,    '•
 Alabama
 Division of Radiation Control
 State Department of Public Health
 434 Monroe Street Room 510
 Montgomery, AL 36130-1701
 (205) 242-5315
 (800) 582-1866 in Alabama

 Alaska
 State Department of Health and Social
 Services
 Division of Public Health
 P.O. Box H
 Juneau, AK  99811-0610
 (907) 465-3019
 (800) 478-4845 in Alaska

 Arizona
 State Radiation Regulatory Agency
 4814 South 40th Street
 Phoenix, AZ 85040
 (602)  255-4845

Arkansas
Division of Radiation Control and
 Emergency Management
State  Department of Health
4815 West Markham Street
Little Rock, AR 72205-3867
(501) 661-2301
 California
 State Department of Health Services
 Environmental Management Branch
 601 North 7th Street
 P.O. Box 942732
 Sacramento, CA 94234-7320
 (916)324-2208
 (800) 745-7236 in California

 Colorado
 Radiation Control Division
 State Department of Health
 4210 East 11th Avenue
 Denver, CO 80220
 (303)  692-3057
 (800)  846-3986 in Colorado

 Connecticut
 State  Department of Health Services
 Radon Program
 150 Washington Street
 Hartford, CT 06106-4474
 (203) 566-3122

 Delaware
 Office of Radiation Control
State Bureau of Environmental Health
 Division of Public Health
P.O. Box 637
Dover, DE 19903
 (302) 739-5728
(800) 554-4636 in Delaware
                                    A-1

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District of Columbia
D.C. Department of Consumer and
  Regulatory Affairs
614 H Street, N.W.
Room 1014
Washington, D.C. 20001
(202) 727-5728; hotline

Florida
Office of Radiation Control
State Department of Health and
  Rehabilitative Services
1317 Winewood Boulevard
Tallahassee, FL 32399-0700
(904) 488-1525
(800) 543-8279 in Florida;
   consumer inquiries only

Georgia
State Department of Human Resources
878 Peachtree Street
Room 100
Atlanta, GA  30309
(404) 657-6534
(800) 745-0037 in Georgia

Guam
Guam Environmental Protection Agency
IT&E Harmon Plaza
D-107
130 Rojas Street
Harmon, Guam 96911
(617) 646-8863

Hawaii
Radiation Branch
State Department of Health
591 Ala Moana Boulevard
Honolulu, HI 96813-2498
(808) 586-4700
Idaho
State Department of Health and Welfare
Bureau of Preventive Medicine
450 West State Street
Boise, ID 83720
(208) 334-6584
(800) 445-8647 in Idaho

Illinois
State Department of Nuclear Safety
1301 Knotts Street
Springfield, IL 62703
(217) 786-7127
(800) 325-1245 in Illinois

Indiana
Radiological Health Section
State Board of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN  46206
(317) 633-0150
(800) 272-9723 in Indiana

Iowa
Radon Control Program
Bureau of Radiological Health
State Department of Public Health
Lucas State Office Building
Des Moines, IA  50319-0075
(515) 242-5992
(800) 383-5992 in Iowa

Kansas
Radiation Control Program
Environmental Health Services
State Department of Health and
  Environment
109 SW 9th Street
6th Floor, Mills Building
Topeka, KS 66612
(913) 296-1561
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 Kentucky
 Radiation Control Branch
 Division of Community Safety
 State Department of Health Services
 Cabinet for Human Resources
 275 East Main Street
 Frankfort, KY 40621
 (502) 564-3700

 Louisiana
 Radiation Protection Division
 Louisiana Department of Environmental
  Quality
 P.O. Box82135
 Baton Rouge, LA 70884-2135
 (504) 925-7042
 (800) 256-2494 in Louisiana

 Maine
 Department of Human Resources
 Division of Health Engineering
 State House, Station 10
 Augusta, ME 04333
 (207) 287-5676
 (800) 232-0842 in Maine

 Maryland
 Radiological Health Program
 State Department of the Environment
 2500 Broening Highway
 Baltimore, MD  21224
 (410) 631-3300
 (800) 872-3666 in Maryland

 Massachusetts
 State Department of Public Health
Western MA Health Office
23 Service Center
 Northampton, MA 01060
 (413)586-7525
 (800) 445-1255
 Michigan
 Division of Radiological Health
 Bureau of Environmental and
  Occupational Health
 State Department of Public Health
 3423 North Logan Street/
  Martin L King Jr. Blvd.
 P.O. Box30195
 Lansing, Ml  48909
 (517) 335-8190

 Minnesota
 State Indoor Air Quality Unit
 925 Delaware Street, SE
 P.O. Box 59040
 Minneapolis, MN  55459-0040
 (612) 627-5012
 (800) 798-9050 in Minnesota

 Mississippi
 Division of Radiological Health
 State Department of Health
 3150 Lawson Street
 P.O. Box 1700
Jackson, MS  39215-1700
 (601)  354-6657
 (800)  626-7739 in Mississippi

 Missouri
 Bureau of Radiological Health
State  Department of Health
 1730 East  Elm
P.O. Box 570
Jefferson City, MO 65102
 (314)  751-6083
 (800)  669-7236 in Missouri

Montana
Occupational Health Bureau
State  Department of Health and
 Environmental  Sciences
Cogswell Building A113
Helena, MT 59620
(406)  444-3671
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 Nebraska
 Division of Radiological Health
 State Department of Health
 301 Centennial Mall, South
 P.O. Box 95007
 Lincoln, NE 68509
 (402)471-2168
 (800) 334-9491 in Nebraska

 Nevada
 Radiological Health  Section
 State Health Division
 505 East King Street, Room 203
 Carson City, NV 89710
 (702)687-5394

 New Hampshire
 Bureau of Radiological Health
 State Div. of Public Health Services
 Health and Welfare Building
 Six Hazen Drive
 Concord, NH  03301
 (603) 271-4674; hotline
 (800) 852-3345x4674 in NH

 New Jersey
 Radiation Protection Programs
 Bureau of Environmental Radiation
 Department of Environmental Protection
  and Energy
 CN 415
 729 Alexander Road
Trenton, NJ 08625-0415
 (609) 987-6396
 (800) 648-0394 in New Jersey

 New Mexico
Hazardous and Radioactive Materials
  Bureau
New Mexico Environment Department
525 Camino De Los  Marquez
P.O. Box 26110
Santa Fe, NM  87502
(505) 827-4300
 New York
 Bureau of Environmental Radiation
  Protection
 State Health Department
 Two University Place
 Albany, NY  12203
 (518) 458-6451
 (800) 458-1158 in New York

 North Carolina
 Division of Radiation Protection
 State Department of Environment,
  Health, and Natural Resources
 P.O. Box 27687
 Raleigh, NC 27611-7687
 (919) 571-4141

 North Dakota
 Division of Environmental
  Engineering
 State Department of Health
 1200 Missouri Avenue, Room 304
 P.O. Box 5520
 Bismarck, ND 58502-5520
 (701) 221-5188

 Ohio
 Ohio Department of Health
 Bureau of Radiological Health Services
246 N. High Street
 P.O. Box 118
 Columbus, OH 43266-0118
 (614) 644-2727
 (800) 523-4439 in Ohio; hotline

Oklahoma
Radiation Protection Division
Oklahoma State Department of Health
P.O. Box 53551
Oklahoma City, OK 73152
(405) 271-5221
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 Oregon
 Department of Human Resources
 State Health Division
 1400 SW 5th Avenue
 Portland, OR 97201
 (503) 731-4014

 Pennsylvania
 State Department of Environmental
  Protection
 Bureau of Radiation Protection
 P.O. Box 2063
 Harrisburg, PA  17120
 (717) 783-3595
 (800) 237-2366 in Pennsylvania

 Puerto Rico
 Radiological Health Division
 G.P.O. Call Box 70184
 Rio Pierdras, Puerto Rico 00936
 (809) 767-3563

 Rhode island
 Division of Occupational and
  Radiological Health
 State Department of Health
 206 Cannon Building
 3 Capitol- Hill
 Providence,  Rl 02908
 (401) 277-2438

South Carolina
Bureau of Radiological Health
State Department of Health and
 Environmental Control
2600 Bull Street
Columbia, SC 29201
(803)  734-4631
(800)  768-0362 in South  Carolina
South Dakota
State Department of Water and
  Natural Resources
523 E. Capitol
Pierre, SD  57501
(605)773-3351
(800) 438-3367

Tennessee
State Department of Health and
  Environment
Division of Air Pollution Control
701 Broadway, 4th Floor
Nashville, TN 37247-3101
828-28861(615)532-0733
(800) 232-1139 in Tennessee

Texas
Radiological Assessment Program
Bureau of Radiation Control
State Department of Health
1100 West 49th Street
Austin, TX 78756
(512)  834-6688

Utah
Division of Radiation Control
Department of Environmental Quality
160 North 1950 West
Salt Lake, UT 84114-4850
(801)  538-6734

Vermont
Occupational and Radiological
  Health Operations
Division of Occupational and
  Radiological Health
State  Department of Health
10 Baldwin  Street,
  Administrative Bldg.
Montpelier,  VT 05602
(802)865-7730
(800)640-0601 in Vermont
                                     A-5

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 Virginia
 Bureau of Radiological Health
 State Department of Health
 109 Governor Street
 Richmond, VA 23219
 (804) 786-5932
 (800) 468-0138 in Virginia

 Virgin Islands
 Contact the U.S. EPA, Region 2 in
  New York
 Mail Code 2AWM-RAD
 26 Federal Plaza
 New York,  NY 10278
 (212)264-4110

 Washington
 Division of  Radiation Protection
 State Department of Health
 Airdustrial Building 5, LE-13
 Olympia, WA 98504
 (206)  753-4518
 (800)  323-9727 in Washington; hotline

 West Virginia
 Office of Environmental Health
  Services
 Industrial Hygiene Division
 State  Bureau  of Public Health
 151 11th Avenue
 South Charleston, WV 25303
 (304) 558-3526
 (800) 922-1255 in West Virginia

Wisconsin
 Radon Program
Radiation Protection Section
Division of Health
State Department of Health and
  Social Services
P.O. Box 309
Madison, Wl 53701-0309
(608) 267-4795
Wyoming
Environmental Health Programs
State Department of Health
Hathway Building, 4th Floor
 (Room 482)
Cheyenne, WY 82002-0710
(307) 777-6015
(800) 458-5847 in Wyoming
                                     A-6

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A.2   EPA REGIONAL RADIATION (RADON) PROGRAM MANAGERS
      There are 10 EPA Regional Program Managers, one for each EPA geographical
Region. (Exhibit A-1 of this appendix contains a map showing the States and their
EPA Regions.)
Region 1
Radiation Program Manager, Region 1
U.S. Environmental Protection Agency
John F. Kennedy Federal Building
Room 2311
Boston, MA  02203
(617) 565-4502

Region 2
Chief, Radiation Branch (AWM-RAD)
U.S. Environmental Protection Agency
26 Federal Plaza, Room 1005A
New York, NY 10278
(212)264-4110

Region 3
Radiation Program Manager, Region 3
Special Program Section (3AM12)
U.S. Environmental Protection Agency
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326

Region 4
Radiation Program Manager, Region 4
U.S. Environmental Protection Agency
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907

Region 5
Radiation Program Manager, Region 5
(5AR26)
U.S. Environmental Protection Agency
230 S.  Dearborn Street
Chicago, IL 60604
(312) 353-2206
Region 6
Radiation Program Manager, Region 6
U.S. Environmental Protection Agency
Chief, Technical Section (6T-ET)
Air, Pesticides and Toxics Division
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7223

Region 7
Radiation Program Manager, Region 7
U.S. Environmental Protection Agency
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7020

Region 8
Radiation Program Manager, Region 8
(8AT-RP)
U.S. Environmental Protection Agency
999 18th Street, Suite 500
Denver, CO 80202
(303) 293-1709

Region 9
Radiation Program Manager, Region 9
(A-1-1)
U.S. Environmental Protection Agency
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048

Region 10
Radiation Program Manager, Region 10
(AT-082) U.S. EPA
1200 Sixth Avenue
Seattle, WA  98101
(206) 442-7660
                                    A-7

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                                  Exhibit A-1

                            MAP OF EPA REGIONS

      Each of the 50 United States, as well as the District of Columbia, the Virgin
islands, and Puerto Rico, has been assigned to one of 10 Federal.Regions.  This map
shows the Regional assignments for the 50 States.  Puerto Rico and the Virgin Islands
are assigned to Region 2; the District of Columbia is in Region 3.
                                                                            RI
        HI
            o
                                    A-8

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                                  APPENDIX B

    INTERPRETATION OF THE RESULTS OF SIDE-BY-SIDE MEASUREMENTS

 B.1   ASSESSMENT OF PRECISION

      Radon and working level measurements, like all measurements, usually do not
 produce exactly the same results, even for collocated measurements. It is therefore
 critical to understand, document, and monitor the variability, or precision, of the
 measurements. This knowledge and proper documentation will allow you to
 characterize precision error to clients. Furthermore, the continual monitoring of
 precision provides a check on every aspect of the measurement system.

      The objective of  performing simultaneous or duplicate measurements is to
 assess the precision error of the measurement method, or how well two side-by-side
 measurements agree.  This precision error is the "random" component of error (as
 opposed to the calibration error, which is systematic).  The precision error,  or the
 degree of disagreement between duplicates, can be composed of many factors.
 These include the error caused by the random nature of counting radioactive decay,
 slight differences between detector construction (for example, small differences in the
 amount of carbon in activated carbon detectors), and differences in handling of
 detectors (for example, differences in accuracy of the weighing process, and
 variations of analysis among detectors).

      There is a variety of ways to quantitatively assess the precision error based on
 duplicate measurements. It is first necessary to understand that precision is
 characterized by a distribution: that is, your side-by-side  measurements will exhibit a
 range of differences. There is some chance that any level of disagreement  will be
 encountered, due merely to the statistical fluctuations of counting radioactive decays.
 The probability of encountering a very large difference between duplicates is smaller
 than the  chance of observing a small difference similar to those that are routinely
 observed. It is important to recognize that a few high precision errors do not
 necessarily mean that the measurement system is flawed.

      Ideally, the results of duplicates should be assessed in a way that allows for the
 determination of what level of chance is associated with a particular difference
 between  duplicates. This will allow for the pre-determination of limits for the allowable
 differences between duplicates before an investigation into the cause of the large
 differences is made. For example, the warning level, or the level of discrepancy
 between  duplicates which triggers an investigation, may be set at a five percent
 probability. This level is a difference between duplicates  that is so large that, when
 compared with previous precision  errors, should only be observed five percent of the
time.  A control limit, where further measurements should cease until the problem is
 corrected, may be  set at one percent probability.
                                      B-1

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       A control chart for duplicates is not as simple as a control chart used to
 monitor instrument performance, as for a check source. This is because the
 instrument's response to a check source should be fairly constant with time.
 Duplicates are performed at various radon concentrations, however, and the total
 difference between two measurements is expected to increase as radon levels
 increase.

       Use of statistics such as the relative percent difference (RPD; difference divided
 by tine mean) or the coefficient of variation (COV; standard deviation divided by the
 mean) can be used in a control chart for duplicate measurements at radon
 concentrations where the expected precision error is fairly constant in proportion to
 the mean, e.g., at levels greater than around 4 pCi/L or 0.02 WL At lower
 concentrations, for example, between 2 pCi/L (or 0.01 WL) and 4 pCi/L  (or 0.02 WL), a
 control chart may be developed by plotting these same statistics; however, the
 proportion of the precision  error to the mean will be greater than that proportion at
 levels above 4 pCi/L or 0.02 WL At concentrations less than about 2 pCi/L, or 0.01
 WL, the lower limit of detection may be approached, and the precision error may be
 so large as to render a control chart not useful.

       Example control charts, using three different statistics, are described in the
 following sections.

 B.2    EXAMPLE CONTROL CHARTS FOR PRECISION

       Before a control chart can be developed, it is necessary to know, from a history
 of making good quality measurements with the  exact measurement system  (detectors,
 analysis equipment, and procedures), the level of precision that is routinely
 encountered when the system is operating well  or "in control."  ft is that "in control"
 precision error that forms the basis of the control chart, and upon which all the
 subsequent duplicate  measurements will be judged.  There are two ways of initially
 determining this "in control" level. The first, and preferable, way is to perform at least
 20 duplicate pairs of measurements at each range of radon concentrations for which a
 control chart is to be prepared.  For example, if you will only assess precision at
 concentrations greater than 4 pCi/L, or 0.02 WL, you will need at least 20 pairs of
 measurements at concentrations greater than 4 pCi/L, or 0.02 WL, to assess the "in
 control" level. The average precision error (RPD or COV) should be the "in control"
 level.

      The second way to initially set the "in  control" precision  error level is to use a
 level that has been used by others, and that is recognized by  industry and EPA as a
goal for precision, for example, a 10 percent COV (corresponding to a 14 percent
 RPD).  After at least 20 pairs of measurements are plotted, it will become apparent
                                      B-2

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 whether the 10 percent COV (or 14 percent RPD) is appropriate for your system  If it
 is not, a new control chart (using the guidelines below) should be prepared so that
 the warning and control limits are set at the correct probability limits for your system.

 B.2.1 Sequential Control Chart Based on Coefficient of Variation

       It can be shown (Iglewicz and Myers 1970, EPA 600/9-76-005; U.S. EPA 1984)
 that when the expected precision is a constant function of the mean, control limits can
 be expressed in terms of the COV (COV=S/Xm; where S is the variance or the square
 of the standard deviation, and ^ is the mean or average of the two measurements)
 One method for obtaining percentiles for the distribution of the COV is to apply a chi-
 squared fo2) test:
                                                  (Equation 1)


 where    B = n[1 + (1/COV2)];

       COVn = the observed COV of the n* pair (the pair that is to be evaluated); and

       COV  = the "in control" COV (e.g., 10 percent at levels greater than 4 pCi/L).

 For duplicates, where n=2, Equation 1 becomes
       X2- [2 + (2/COV2)J[COVn2/(2 + COV,,2)]       (Equation 2)
 For a value of 0.10 for COV, jt further reduces to
= 202[COVn2/(2 + COVn2)]
                                                (Equation 3)
Referring to a %  chart, you learn that the probability of exceeding a x2 of 3 84 is only
five percent. Inserting this value of 3.84 for %2 and solving for COVn, produces a
COVn of 0.20.  This level of probability forms the warning level shown in Exhibit B-1
The control limit corresponds to a x2 of 6.63 and a COVn of 0.26, where the
probability of exceeding those values is only one percent.

      This  sequential control chart should be used by plotting results from each pair
on the y-axis, and noting the  date and measurement numbers on the x-axis.
                                     B-3

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B.2.2 Sequential Control Chart Baaed on Relative Percent Difference

      The RPD (or percent difference) is another expression of precision error, and is
given by
      RPD =
(Equation 4)
For
                                                (Equation 5)
The control limits for RPD can be obtained simply by multiplying the control limits for
COV by the square root of two, or 1.41. These limits are shown in Exhibit B-2. This
sequential control chart for RPD should be used in the same way as the control chart
for COV, that is, with the vertical scale in units of RPD and the horizontal scale in units
of date and measurement numbers.

      A control chart using the statistic RPD based on an "in control" level of 25
percent RPD is shown in Exhibit B-3. The warning level and control limit are set at 50
percent and 67 percent, respectively.  Use of these limits may be  appropriate for
measured radon concentrations less than  4 pCi/L
                                      B-4

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                                  Exhibit B-1
                          ซ

                 Control Chart* for Coefficient of Variation (COV)
                      Based on an "In Control" Level of 10%
                (For duplicates where average .>4 pCi/L or 0.02 WL)
               26%
                              Control Limit
         I
         'o
         •ฃ
         j>
         _o
         s
         5
20%
                              - Expect to see duplicates produce COV greater
                               than 26% only 1% of the time (1/100 chance)
                Warning Level
              10%
               - Expect to see duplicates produce COV greater
                 than 20% only 5% of the time (1/20 chance)
                              'In Control" Level
                             - Expect to see results routinely produce this COV
                              -I—I-
                                Date and Measurement Number

COV=standard deviation of two measurements divided by their average
Example:  Detector A=5 pCi/L, B=6 pCi/L, COV=13%

If COV exceeds the control limit-cease measurements until the problem is identified
and corrected.

If COV exceeds the warning level-follow guidance in Section B.3 and see Exhibit B-5.

*As calculated from guidance provided in "Quality Assurance Handbook for Air
Pollution Measurement Systems: Volume I" (EPA 600/9-76-005; U.S. EPA 1984)
                                    B-5

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                                Exhibit B-2

             Control Chart* for Relative Percent Difference (RPD)
            Based on an "In Control" Level of 14% (=COV of 10%)
              (For duplicates where average ^4 pCi/L or 0,02 WL)
           36%

      i
      1
           28
           14%
                          Control Limit
                          - Expect to see duplicates produce RPD greater
                           than 36% only 1% of the time (1/100 chance)
                          Warning Level
- Expect to see duplicates produce RPD greater
 than 28% only 5% of the time (1/20 chance)
                           'In Control" Level
                          - Expect to see results routinely produce this
                              Date and Measurement Number
RPD=d'rfference between two measurements divided by their average
Example: Detector A=5 pCi/L, B=6 pCi/L, RPD=18%

If RPD exceeds the control limit-cease measurements until the problem is identified
and corrected.

If RPD exceeds the warning level-follow guidance in Section B.3 and see Exhibit B-5.

*As calculated from guidance provided in "Quality Assurance Handbook for Air
 Pollution Measurement Systems: Volume I" (EPA 600/9-76-005; U.S. EPA 1984)
                                    B-6

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        3
        ฃ
        0)

                                  Exhibit B-3

               Control Chart* for Relative Percent Difference (RPD)
              Based on an "In Control" Level of 25% (=COV of 18%)
                (For duplicates where average <4 pCi/L or 0.02 WL)
            67%
            50%
 Control Limit
1^I^^^M             	
 - Expect to see duplicates produce RPD greater
  than 67% only 1% of the time (1/100 chance)
Warning Level	
- Expect to see duplicates produce RPD greater
 than 50% only 5% of the time (1/20 chance)
            25%J
 In Control" Level    	
- Expect to see results routinely produce this RPD
                              Date and Measurement Number
RPD=difference between two measurements divided by their average
Example:  Detector A=2 pCi/L, B=3 pCi/L, RPD=40%

If RPD exceeds the control limit-cease measurements until the problem is identified
and corrected.

If RPD exceeds the warning level-follow guidance in Section B.3 and see Exhibit B-5.

*As calculated from guidance provided  in "Quality Assurance Handbook for Air
Pollution Measurement Systems: Volume I" (EPA 600/9-76-005; U.S. EPA 1984)
                                    B-7

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B.2.3. Range Control Chart

      A range control chart (Goldin 1984) can be constructed to evaluate precision,
using the statistics of the range (difference between two measurements) plotted
against the average of the two measurements. The control limits are again based on
the variability of the  measurements, as decided upon from previous results or using an
industry standard (e.g., 10 percent).

      In this type of control chart, the limits are expressed in terms of the mean range
    , where, for n=2,
                                                (Equation 6)
where s(x) is the standard deviation of a single measurement, which reflects counting
and other precision errors. Goldin shows that the limits can be expressed as follows:
       Control limit = 3.69 s(x)
(Equation 7)
       Warning level = 2.53 s(x)
(Equation 8)
 An example range control chart, using an assumed s(x) equal to 10 percent of the
 mean concentration, is shown in Exhibit B-4.  The chart is used by plotting the range
 versus average concentration as duplicate measurements are analyzed.
                                       B-8

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                                    Exhibit B-4

                     Range Control Chart to Evaluate Precision
                           (Limits Based on sfxJ^O.
                      0        5       10       15       20       25
                         Average Value of Two Measurements, pCi/L
                                    measurements until the problem is identified
If results exceed the warning level-follow guidance in Section B.3 and see Exhibit B-5.
                                     B-9

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B.3   INTERPRETATION OF PRECISION CONTROL CHARTS

      The control chart should be examined carefully every time a new duplicate
result is plotted.  If a duplicate result falls outside the control limit, repeat the analyses
if possible.  If the repeated analyses also fall outside the control limit, stop making
measurements and identify and correct the problem.

      If any measurements fall outside the warning level, use the table in Exhibit B-5.
Refer to the row showing the number of duplicate results outside the warning level.  If
the total number of duplicate results accumulated in the control chart is contained in
column A, investigate the cause of the high level of precision error but continue
making measurements.  If the total number of duplicate results on the chart is
contained in column B, stop making measurements until the cause for the high
precision error is found, and it is determined that subsequent measurements will not
suffer the same high level of precision error.

      Note that the example control charts shown here are simplifications of actual
conditions, because they are premised on the assumption that the precision error is a
constant fraction of the mean concentration. In fact, the total precision error may best
be represented by a different function of the mean concentration, for example, the
square root of the concentration. The most accurate control chart can be rendered
by a  range control chart using the measurement uncertainty expressed as the
standard deviation, s(x), expected at the concentrations where measurements are
made. If the precision error is not a constant fraction of the mean, the control limits
will not appear as straight lines, but may exhibit changing slope.  However,  methods
discussed here present a conservative way to monitor, record, and evaluate precision
error and are very useful for comparing observed precision errors with an industry
standard.
                                      B-10

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                               Exhibit B-5

  Criteria for Taking Action for Measurements Outside the Warning Level*
   Number of
Duplicate Results
   Outside the
 Warning Level
                           Total Number of  Duplicates
  Investigate, But
Continue Operations
Stop Operations
Until Problem is
   Corrected

       B
                            8-19
                              2-7
                            17-34
                              8-16
                            29-51
                             17-28
                            41-67
                             29-40
                            54-84
                             41-53
                           67-100
                             54-66
   Modified from Goldin (Goldin 1984) and based upon cumulative probability
   tables of the binomial distribution.
                                B-11

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                                  GLOSSARY

 Accuracy:  The degree of agreement of a measurement (X) with an accepted
       reference or true value (T); usually expressed as the difference (or bias)
       between the two values (X - T), or the difference as a percentage of the
       reference or true value (100[X - TjA), and sometimes expressed as a ratio
       (X/T).

 Active radon/radon decay product measurement device:  A radon or radon decay
       product measurement system which uses a sampling xlevice, detector, and
       analysis system integrated as a complete unit or as separate, but portable
       components.  Active devices include continuous radon monitors, continuous
       working level monitors, and grab radon and grab working level measurement
       systems, but do not include devices such as electret ion chamber devices
       activated carbon or other adsorbent systems, or alpha track devices!

 Alpha particle:  Two neutrons and two protons bound as a single particle that is
       emitted from the nucleus of certain radioactive isotopes in the process of
       radioactive decay.

 Background instrument (analysis system, or laboratory) count rate:  The nuclear
       counting rate obtained on a given instrument with a background counting
       sample. Typical instrument background measurements are:-

       •      Unexposed carbon: for activated carbon measurement systems.

       •      Scintillation vial containing scintillant and sample known to contain no
             radioactivity: for scintillation counters.

       •      Background measurements made with continuous.radon monitors
             exposed onjy to radon-free air (aged air or nitrogen).

Background field measurement (blanks):  Measurements made by analyzing
      unexposed (closed) detectors that accompanied exposed detectors to the field
      Tlie purpose of field background measurements is to assess any  exposure to
      the detector caused by radon exposure other than from the concentration in
      the environment to be measured.  Results of background field measurements
      are subtracted from the actual field measurements before calculating the
      reported concentration.  Background levels may be due to electronic noise of
      the analysis system, leakage of radon into the detector, detector response to
      gamma radiation, or other causes.
                                    G-1

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Background radiation: Radiation arising from radioactive materials, the sun, and
      parts of the universe, other than that under consideration. Background
      radiation due to cosmic rays and natural radioactivity is always present;
      background radiation may also be due to the presence of radioactive
      substances in building  materials.

Becquerel (Bq):  The International System of Units (SI) definition of activity.  1 Bq = 1
      disintegration per second.

Calibrate:  To determine the response or reading of an instrument relative to a series
      of known values over the range of the instrument;  results are used to develop
      correction or calibration factors.

Check source: A radioactive source, not necessarily calibrated, which is used to
      confirm the continuing  consistent and  satisfactory  operation of an instrument.

Client:  The individual or parties who hire(s)  the radon tester.

Closed House Conditions: During any short-term test,  closed-house-conditions
should be maintained as much as possible while the test is in progress. In tests of
less than 4 days duration, closed-house-contiions should be maintained for at least
12-hours before starting the test and for the  duration of the test. While closed-house-
conditions are not required before the start of tests that are between 4 and 90-days
long,  closed-house-conditions should be maintanined as much as possible.

Coefficient of variation (COV), relative standard deviation  (RSD): A measure of
      precision, calculated as the standard deviation (s or a) of a set of values
      divided by the average (Xave or n), and usually multiplied by 100 to be
      expressed as a percentage.

      COV = RSD = (s/Xave) x 100 for a sample,

      or

      COV' = RDS' = (a//u) x 100 for a population.

      See Relative percent difference.

Curie (Ci):  A commonly used measurement unit for radioactivity in the United States,
      specifically the approximate rate of decay for a gram of radium = 37 billion
      decays per second. A unit of radioactivity equal to 3.7 x 1010 disintegrations
      per second.
                                       G-2

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  Duplicate measurements: Two measurements made concurrently and in the same
        location, side-by-side.  Use to evaluate the precision of the measurement
        method.

  Efficiency, intrinsic detector: The relationship between the number of events
        recorded (counts, voltage lost, tracks) and the number of radioactive particles
        incident upon the sensitive element of the detector per unit time.  Efficiencies
        for radon detectors are commonly expressed in terms of the calibration factor
        which is the number of events (counts) per time (hour or minute) per radon  '
        concentration (pCi/L).  Methods with high efficiencies will exhibit more counts
        (signal) per time in response to a given radon level than will a method with a
        low efficiency.

 Equilibrium ratio, radon:  Equilibrium ratio = [WL(100)]/(pCi/L). At complete
       equilibrium (i.e., at an equilibrium ratio of 1.0), 1 WL of RDPs would be present
       when the radon concentration was 100 pCi/L. The ratio is never  1.0 in a house
       Due to ventilation and plate-out, the RDPs never reach equilibrium in a
       residential environment. A commonly assumed equilibrium ratio is 0.5 (i e  the
       decay products are halfway toward equilibrium), in which  case 1 WL would
       correspond to 200 pCi/L  However, equilibrium ratios vary with time and
       location, and ratios of 0.3 to 0.7 are commonly observed.

 Equilibrium equivalent concentration (EEC): The radon concentration in equilibrium
       with its short-lived progeny, that has the same potential alpha energy per
       volume as exists in  the environment being measured (see working level).

 Exposure time:  The length of time a specific device must be in  contact with radon or
       radon decay products to get an accurate radon measurement. Also called
       exposure  period, exposure parameter, or duration of exposure.

 Gamma radiation: Short.wavelength electromagnetic radiation of nuclear origin  with
       a wide range of energies.                                         a

 Integrating device: A device that produces a measurement of the average
      concentration over a period of time.  Also called a time-integrating device.

Lower limit of detection (LLD): The smallest amount of sample activity  which  will
      yield a net count for which  there is confidence at a predetermined level that
      activity is present. For a five percent probability of concluding falsely that
      activity is present, the LLD may be approximated by a value of 4.65 times the
      standard deviation of the background counts (assuming large numbers of
      counts where Gaussian statistics can be used [ANS11989, Pasternack and
      Harley 1971, U.S.  DOE 1990]).
                                     G-3

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Lowest level suitable for occupancy: The lowest level currently lived jn or, a lower
      level not currently used, such as a basement, which a prospective buyer could
      use for living space without renovations. This includes a basement that could
      be used regularly, as for example a recreation room, bedroom, den, or
      playroom.

Lowest lived-ln level: The lowest level or floor of a home that is used regularly,
      including areas such as family rooms, living rooms, dens, playrooms, and
      bedrooms.

Passive radon measurement device: A radon measurement system in which the
      sampling device, detector, and measurement system do not function as a
      complete, integrated unit.  Passive devices include electret ion chamber
      devices, activated carbon or other adsorbent systems, or alpha track devices,
      but do not include continuous radon/radon decay product monitors, or grab
      radon/radon decay product measurement systems.

Plcocurie (pCi):  One pCi is one trillionth (10'12) of a curie, 0.037 disintegrations per
      second, or 2.22 disintegrations per minute.

Picocurie per liter (pCi/L): A unit of radioactivity corresponding to an average of
      one decay every 27 seconds in a volume of one liter, or 0.037 decays per
      second in a liter of air or water. 1  pCi/L = 37 Becquerels per cubic meter
      (Bq/m3).

Precision: A  measure of mutual agreement among individual measurements made
      under similar conditions.  Can be expressed in terms of the variance, pooled
      estimate of variance, range, standard deviation at a particular concentration,
      relative percent difference, coefficient of variation or other statistic.

Quality assurance:  A complete program designed to produce results which are
valid, scientifically defensible, and of known precision, bias, and accuracy.  Includes
      planning, documentation, and quality control activities.

Quality control:  The system of activities to ensure a quality product, including
      measurements made to ensure and monitor data quality.  Includes calibrations,
      duplicate, blank, and spiked measurements, interlaboratory comparisons, and
       audits.

Radon (Rn):  A colorless, odorless, naturally occurring, radioactive, inert, gaseous
       element formed by radioactive decay of radium (Ra) atoms.  The atomic
       number is 86.  Although other isotopes of radon occur in nature,  radon in
       indoor  air is primarily Rn-222.
                                      G-4

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  Radon chamber:  An airtight enclosure in which operators can induce and control
        different levels of radon gas and radon decay products. Volume is such that
        samples can be taken without affecting the levels of either radon or its decay
        products within the chamber.                                          y

  Relative percent difference (RPD):  A measure of precision, calculated by:

        RPD -  [(IX, - XjJj/X^J x 100

        where:

        X^concentration observed with the first detector or equipment;

        ^concentration observed with the second detector, equipment, or absolute
            value;

        IX, - Xjj^absolute value of the difference between X, and X& and

       xซve=average concentration =  ((X, +XJ/2).

       The RPD and coefficient of variation (COV) provide a measure of precision but
       they are not equal.  Below are example duplicate radon results and the
       corresponding values of RPD and COV:
       Rn1
     foCi/U
        8
       13
       17
       26
        7.5
  Rn2
foCi/L)
  9
  15
  20
  30
  10
RPD
COV
12
14
16
14
29
  8
 10
 11
 10
 20
       Note that the RPD/1/2 = COV.
      See Coefficient of variation (COV).

Relative standard deviation: See Coefficient of variation.

Sensitivity: The ability of a radon or WL measurement method to produce reliable
      measurements at low concentrations. This ability is dependent upon the
      variability of the background signal (counts not due to radon or WL exposure)
      which the method records, as well as its efficiency.  Methods with stable
      background rates and high efficiencies will be able to produce reliable
                                     G-5

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      measurements at lower concentrations than methods with variable background
      rates and low efficiencies.  Sensitivity can be expressed in terms'of the lower
      limit of detection or minimum detectable activity.

Signal-to-noise ratio:  For radon and WL detectors, this term expresses the
      proportion of the number of counts due to exposure to radon or WL (signal) to
      the number of counts due to background (noise). Measurement methods with
      high signal-to-noise ratios will produce more counts due to radon or WL
      exposure (signal) in proportion to the background counts (noise) than will
      methods with low signal-to-noise ratios.  A method with a high signal-to-noise
      ratio is more likely to exhibit good sensitivity, i.e., be able to produce reliable
      measurements at low concentrations.

Spiked measurements, or  known exposure measurements: Quality control
      measurements in which the detector or instrument is exposed to a known
      concentration in a calibration facility and submitted for analysis. Used to
      evaluate accuracy.

Standard deviation (s):  A measure of the scatter of several sample values around
      their average.  For a sample, the standard deviation (s) is the positive square
      root of the sample variance:
                            s =
                                    ฃ (Xi -Xave)
       For a finite population, the standard deviation (a) is:
                              o =
                                         v/N
       where p. is the true arithmetic mean of the population and N is the number of
       values in the population.  The property of the standard deviation that makes it
       most practically meaningful is that it is  expressed in the same  units as the
       observed variable X.  For example, the upper 99.5 percent probability limit on
       differences between two values is 2.77 times the sample standard deviation.

 Standard  operating procedure:   A written document which  details  an  operation,
       analysis, or action whose mechanisms are prescribed thoroughly  and which is
       commonly accepted as the method for performing certain routine or repetitive
       tasks.
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  Statisticafjsontrol chart (Shewhart control chart): A graphical chart.with statistical
        control limits and plotted values (for some applications in chronological order) of
        some measured parameter for a series of samples. Use of the charts provides a
        visual display of the pattern of the data, enabling the early detection of time trends
        and shifts in level.  For maximum usefulness in control, such char> should be
        plotted in a timely manner (i.e., as soon as the data are available). See Appendix
        B.

  Statistical controS chart limits:  The limits  on control charts that have been  derived
        by statistical analysis and are used as criteria for action, or for judging whether a
        set of data does or does not indicate lack of control.  On a means control chart
        the warning level (indicating the need for an investigation) may be two standard
        deviations above and below the mean, and the control limit (indicating the need
        to haft operations until the problem is identified and corrected) may be  three
        standard deviations above and below the mean.

 Systeme Internationale  (SI):  The  International System of Units as  defined  by the
        Conference of Weights and Measures in 1960.

 Test Interference:  The altering of test conditions prior to or during the measurement in
       order to change the radon or radon decay product concentrations or the altering
       of the performance of the measurement equipment.

 Time  integrated measurement:   A measurement conducted over a specific time
       period (e.g., from two days to a year or more) producing results representative of
       the average value for that period.

 Uncertainty:  The range of values within which the true value is estimated to lie  It is
       1SS.TmatS of Pฐssible error due  to both random errors (imprecision) and
       systematic errors (that produce -bias, or inaccuracies),

 Working level (WL): Any combination of short-lived radon decay  products in one liter
       of air thatwill result in the ultimate emission of 1.3 x 10s MeV of potential alpha
       energy  This number was chosen because it is approximately the alpha energy
       released from the decay  products in  equilibrium with 100  pCi of Rn-222

       ? W=
Working  level  months  (WLM):    (working  level  x hours of  exposure
      hours/working month).  In SI units, 1  WLM = 6 x 105 Bq-h/m3 (EEC).
                                     G-7

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                                  REFERENCES

  Aftshuler, B. and Pasternack, B., 1963, Statistical Measures of the Lower Limit of
  Detection of a Radioactivity Counter, Health Phvsics. Vol. 9, pp. 293-298.

  American Association of Radon Scientists and Technologists (AARST), 1991  Draft
  Standard: Radon/Radon Decay Product Instrumentation Test and Calibration  AARST
  Park Ridge, New Jersey.


  American National Standards Institute (ANSI), 1989, Performance Specifications for
  Health Physics Instrumentation-Occupational Airborne Radioactivity Monitoring
  Instrumentation, ANSI N42.17B-1989, The Institute of Electrical and Electronics
  Engineers, Inc., New York, New York.


 Arvela, H.f Voutilainen, A., Makelainen, I., Castren, O., and Winqvist, K.  1988
  Companson of Predicted and Measured Variations of Indoor Radon Concentration
  Radiat. Prot. Dosim  Vol. 24, No. 1/4, pp. 231-235.

  Chapin, Jr., F.S., 1974, Human Activity Patterns in the City: Things People Do in Time
 and Space, John Wiley and Sons, New York, NY.


 5Ud"eyUC>S" Hawthome. A.R.. Wallace, R.G., and Reed, R.P., 1990, Radon-222
 Rn-222 Progeny and Rn-222 Progeny Levels in 70 Houses, Health Phvsics  Vol. 58,
 NO. 3, pp. 297-31 1 .


 Fleischer R.L and Turner, L.G., 1984, Indoor Radon Measurements in the New York
 Capital District, Health Phvsies Vol. 46, pp. 999-1011.
 rrVo yh0?"1-9^- 3"d Bu:kart' W" 1991' **ปป*ป ofRn Transport From the
 Cellar to the Living Area in an Unheated House, Health Phvsics  Vol. 60, No. 3, pp.
    ~
Gesell, T.F., 1983, Background Atmospheric Rn-222 Concentrations Outdoors and
Indoors: A Review, Health Phvsics. Vol. 45, pp. 289-302.


George, A.C., Duncan, M., and Franklin, H., 1984, Measurements of Radon in
29?-294   Buildin9S in Wa/y/and and Pennsylvania, Radiat. Prot. Dosim  Vol. 7, pp.


Goldin, A.S., 1984, Evaluation of Internal Quality Control Measurements and
Radioassay, Health Phvsics  Vol. 47, No. 3, pp. 361-364.


Harley, N.H  1991, Radon Levels in a High-Rise Apartment, Health Phvsics Vol. 61,
No. 2, pp. 263-265.
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-------
Hess, C.T., 1985, Field and Laboratory Tests of Etched Track Detectors for Rn-222:
Summers-Winter Variations and Tightness Effects in Maine Houses. Health Physics.
Vol. 49, pp. 65-79.

Iglewicz, B. and Myers. R.H., February 1970, Comparison of Approximations to the
Percentage Points of the Sample Coefficients of Variation, Technometrics. Vol. 12, No.
1, pp. 166-170.

Keller, G., Folkerts, K.H., and Muth, H., 1984, Special Aspects of the Rn-222 and
Daughter Product Concentrations in Dwellings and the Open Air, Radiat. Prot. Dosim..
Vol. 7, pp. 151-154.

Martz, D.E., Rood, A.S., George, J.L, Pearson, M.D., and Langner, Jr., G.H., 1991,
Year-to-Year Variations in Annual Average Indoor Rn-222 Concentrations, Health
Physics. Vol. 61. No. 3. pp. 409-413.

Moeller, D.W. and Underhill, D.W.,  December 1976, Final Report on Study of the
Effects of Building Materials on Population Dose Equivalent, School of Public Health,
Harvard University, Boston, MA.

Nyberg, P.O. and Bemhardt, D.E., 1983, Measurement of Time-Integrated Radon
Concentrations in Residences, Hearth Phvsics. Vol. 45, pp. 539-543.

Pastemack, B.S. and Harley, N.H., 1971, Detection Limits for Radionuclides in the
Analysis of Multi-Component Gamma Ray Spectrometer Data, Nuclear Instr. and
Methods. Vol. 91, pp. 533-540.

Perritt, R.L, Hartwell, T.D., Sheldon, L.S., Cox, B.G., Clayton, C.A., Jones, S.M., and
Smith, M.L, 1990, Radon-222 Levels in New York State Homes, Health Phvsics. Vol.
58, No. 2, pp. 147-155.

Put, LW. and de Meijer, R.J., 1988, Variation of  Time-Averaged Indoor and Outdoor
Radon Concentrations with Time, Location and  Sampling Height, Radiat. Prot. Dosim..
Vol. 24, No. 1/4, pp. 317-320.

Ronca-Battista, M. and Magno, P., 1988, A Comparison of the Variability of Different
Techniques and Sampling Periods for Measuring Rn-222 and its Decay Products,
Health Phvsics. Vol. 55, No. 5, pp. 801-807.

Steck, D.J., 1992, Spatial and Temporal Indoor Radon Concentrations,  Health Phvsics.
Vol. 62, No. 4, pp. 351-355.

Stranden, E., Berteig, L, and Ugletveit, F., 1979, A Study on Radon in Dwellings,
Health Phvsics. Vol. 36, pp. 413-421.
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  Szalai, A., 1972, The Use of Time: Daily Activities of Urban and Suburban Populations
  in Twelve Countries, Mouton, The Hague, Paris.

  U.S. Department of Energy, 1990, Procedures Manual, U.S. DOE Environmental
  Measurements Laboratory, 376 Hudson Street, N.Y., N.Y. 10014-3621 (HASL-300).

  U.S. Environmental Protection Agency, 1980, Interim Guidelines and Specifications for
  Prepanng Quality Assurance Project Plans, QAMS-005/80, Office of Monitoring
  Systems and Quality Assurance, Office of Research and Development, Washington,
  D.C.

  U.S. Environmental Protection Agency, December 1984, Quality Assurance Handbook
  for Air Pollution Measurement Systems: Volume 1,  EPA 600/9-76-005, Washington,


  U.S. Environmental Protection Agency, 1987, Interim Protocols for Screening and
  Follow-up Radon and Radon Decay Product Measurements, EPA 520/1-86-014-1
  Office of Radiation Programs, Washington, D.C.

  U.S. Environmental Protection Agency, 1991, Radon Measurement Proficiency (RMP)
 Program Handbook, EPA 520/1-91-006, Office of Radiation Programs, Washington,
  D.C.
 H' ?i E™ron™ฎntal Protection Agency, Office of Radiation Programs; U.S. Department
 ?™   h ซnd Human Services- Publ'c Health Service, Centers for Disease Control
 1 992a, A Citizen's Guide to Radon, EPA 402-K-92-001 , Washington, D.C.

 US. Environmental Protection Agency, 1992b, Consumer's Guide to Radon
 Reduction, EPA 402-K-92-003, Office of Air and Radiation, Washington, D.C.

 US Environmental Protection Agency, 1992c, Indoor Radon and Radon Decay
 Product Measurement Device Protocols, EPA 520-402-R-92-004, Office of Radiation
 Programs, Washington, D.C.

 US. Environmental Protection Agency, I992d, Interim Radon Mitigation Standards
 Office of Radiation Programs, Washington, D.C.

 U.S. Environmental Protection Agency, I992e, National Radon Measurement
 Proficiency Program, National Proficiency Report. EPA 520/1-91-014-3N Office of Air
 and Radiation, Washington, D.C.

 U.S. Environmental Protection Agency, 1992f, Radon Contractor Proficiency (RCP)
Program Application Information Packet, EPA 402-K-92-001 , Washington, D.C.
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U S. Environmental Protection Agency, 1992g, Technical Support Document for the
1992 Citizen's Guide to Radon, EPA 400-R-92-011, Office of Air and Radiation,
Washington, D.C.

U.S. Environmental Protection Agency, 1993, Home Buyer's and Seller's Guide to
Radon, EPA 402-R-93-003, Office of Radiation Programs, Washington, D.C.

Wilkening, M. and Wicke, A., 1986, Seasonal Variations of Indoor Rn at a Location in
the Southwestern United States, Health Physics. Vol. 51, pp. 427-436.

Wilson, D.L, Gammage, R.B., Dudney, C.S., and Saute, R.J., 1991, Summertime
Elevation of Rn-222 Levels in Huntsville, Alabama, Health Physics. Vol. 60, No. 3,  pp.
393-398.
     •U.S. Government Printing Office: 1996 - 715-003/50509
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