Office of Air and Radiation
EPA 402-R-93-003, June 1993

PROTOCOLS FOR RADON AND RADON DECAY
PRODUCT MEASUREMENTS IN HOMES

Section 4: GENERAL PROCEDURAL RECOMMENDATIONS

4.1 Introduction
4.2 Initial Client Interview
4.3 Measurement Recommendations
4.4 Quality Assurance in Radon Testing
4.5 Standard Operating Procedures
4.6 Providing Information to Consumers
4.7 Reporting Test Results
4.8 Temporary Risk Reduction Measures
4.9 Recommendations for Mitigation
4.10 Worker Safety

4.1 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 of:

Go to Top of Page

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 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.

Adherence to the EPA device protocols, Indoor Radon and Radon Decay Product Measurement Device Protocols (EPA 520-402-R-92-004; U.S. EPA 1992c) was a requirement for participation in EPA's former National Radon Proficiency Program (RPP).

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 occupant, if different) 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). 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 typical of the home environment, but that 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.

  • Specific information on the minimum and maximum duration of exposure for the device.

  • If the client will be performing the test, procedures for placing, retrieving, 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 client which confirms that they followed all instructions and did not interfere with the conditions or the measurement device.

    Include the introduction of unconditioned air into the home or closure of normally accessible areas of the home. In this case, the measurement organization should inform the client 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 clients with a written statement that discusses the importance of proper measurement conditions and of not interfering with the measurement device or building conditions. This non-interference agreement should be signed and returned by the client confirming that they followed all written instructions and did not interfere with the measurement device.

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. 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.

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 of the measurement duration (and any times required for analysis).

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

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

  • EPA's former National Radon Proficiency Program (RPP) listed organizations used to analyze devices, check with your State Radon Contact for information on proficient radon testers and other State requirements.

  • 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 easurements.

Go to Top of Page

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 radonenvironment, 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 measurements, with a minimum of three per year and a maximum required of six per month. Providers of measurements with active devices were, under EPA's former RPP, required to recalibrate their instruments at least once every 12 months and perform cross-checks with RPP-listed devices at least once every six months. Participation in EPA's former National Radon Proficiency Program did not satisfy the need for annual calibration, as this Program was 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 Measurment 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, ANSI 1989, 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).

4.4.4 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 (QAP) appropriate to each device or method used. This was a requirement for participation in EPA's former National Radon Proficiency Program (RPP). Specific guidance on the necessary quality control measures for each measurement method is provided in EPA's Indoor Radon and 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 former Radon Proficiency Program (RPP), please contact the EPA at (202) 564-9370 or via fax at (202) 565-2038, or write to:

U.S. Environmental Protection Agency
Office of Radiation and Indoor Air/Indoor Environments Division (6609J)
401 M. St., SW
Washington, DC 20460

Go to Top of Page

4.5 Standard Operating Procedures

Organizations performing radon measurements should have a written, device-specific standard operating procedure (SOP) in place for each radonmeasurement 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).

Go to Top of Page

4.6 Providing Information to Consumers

Organizations should provide the customer with the following information:

Go to Top of Page

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:

Go to Top of Page

4.8 Temporary Risk Reduction Measures

Contractors should refer home's occupants and agents to EPA's 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 that altered conditions during the measurement will invalidate the results and decline to conduct a measurement until the conditions have been corrected.

Go to Top of Page

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). Because EPA has closed its National Radon Proficiency Program (RPP), consumers should contact their State Radon Contacts to verify any State requirements for measurement and mitigation service providers in their states.

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 for any requirements for radon service providers on their own State-listed or other privately-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.

Go to Top of Page

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.

Go to Top of Page

Table of Contents || Section One || Section Two || Section Three || Appendices || Glossary || References

http://www.epa.gov/iaq/radon/pubs/homprot5.html
Created: July 30, 1999