NRPP RMI cheat sheet

Radon-222 is a noble gas produced by alpha decay of Ra-226 (half-life 1600 y); its own half-life is 3.82 days, and it decays through short-lived progeny (Po-218, Pb-214, Bi-214, Po-214) that emit the alpha particles relevant to dose.

Units: 1 pCi/L = 37 Bq/m3; working level (WL) = 100 pCi/L of radon in equilibrium with progeny (2.08 x 10^-5 J/m3 of potential alpha energy); 1 WLM = 170 WL-hours per month (approx. 200 pCi/L for one working month at home occupancy).

EPA action level for homes is 4 pCi/L; the EPA recommended action level for schools and large buildings is also 4 pCi/L, with follow-up testing required at 4 pCi/L or above and consideration of mitigation between 2 and 4 pCi/L.

Equilibrium ratio (ER) = actual progeny concentration divided by the equilibrium-adjusted radon concentration; typical indoor ER is 0.3-0.7. Working level ratio (WLR) relates measured WL to radon concentration: WL = (Rn pCi/L) x ER / 100.

Short-term tests run 2-90 days; the EPA protocol for real-estate and general screening uses a minimum 48-hour closed-building test (12 hours closed before the test begins, doors and windows closed, normal HVAC operation with no exhaust fans).

Long-term tests run more than 90 days (typically 3-12 months) and are preferred because they average seasonal variation; radon in the lowest lived-in level is normally highest in winter and lowest in summer.

Detection methods: activated charcoal adsorption (short-term, 2-7 days, sensitive to temperature and humidity), alpha-track/electret ion chambers (long-term), continuous radon monitors (CRM, hourly data, require calibration and anti-tamper features), and charcoal liquid scintillation.

Placement rules: 20 inches (50 cm) above the floor, at least 12 inches (30 cm) from exterior walls, at least 4 inches (10 cm) from other objects, at least 3 feet (91 cm) from windows, doors, or vents, and not in bathrooms, kitchens, laundry rooms, closets, or crawl spaces.

Duplicate/blank QA: at least 10% duplicates and 5% blanks, or one of each per 10 measurements if fewer than 10 devices are deployed; results must be reported to the client in the units and time frame specified by the client's protocol.

A measurement professional must be certified by an EPA-recognized proficiency program (NRPP or NRSB) and maintain device-specific certification; each device type listed on the certification is separately covered and requires its own QA records.

Spike tests verify accuracy against a known radon concentration; at least 3 spiked devices per 100 deployed devices (or 3 per year for low-volume testers) must be analyzed, and results should be within +/- 25% of the known value (or +/- 10% for CRM calibration checks).

Duplicate measurements assess precision: at least 10% of deployed devices or 50 per year, whichever is smaller, with relative percent difference (RPD) between duplicates typically within 25% for charcoal and 20% for alpha-track.

Blank (background) devices are undeployed devices analyzed to detect contamination or detector background; at least 5% of deployed devices or 25 per year, whichever is smaller, and blank results should be below the device's lower limit of detection.

CRM calibration: continuous monitors must be calibrated at least annually with a known radon source (or cross-calibrated against a calibrated CRM), and calibration factors documented; a daily check source or internal self-test is required each day of use.

Lower limit of detection (LLD) for charcoal devices is typically 0.5-1.0 pCi/L; results below the LLD should be reported as less than that value, not as zero. Alpha-track LLDs are typically 0.3-1.0 pCi/L depending on exposure length.

Reporting requirements: report results in pCi/L (or Bq/m3), identify the test method and device, state test start and end dates, closed-building conditions, and the EPA action level of 4 pCi/L; include a recommendation for follow-up testing when results are 4 pCi/L or higher.

Chain-of-custody: devices must be logged with deployment and retrieval dates/times, location, and device serial numbers; samples must reach the lab within the device's hold time (typically 7 days for charcoal, longer for alpha-track).

Tamper indicators: a CRM must record hourly data and show no evidence of tampering or unusual environmental conditions (e.g., doors/windows open, high humidity); a test with evidence of interference should be invalidated and repeated.

Real-estate test protocol: the test must be conducted in the lowest livable level, with the building closed for 12 hours before the test starts, and the test must last at least 48 hours; the seller and buyer must be informed that the test is being conducted and must not interfere with closed-building conditions.

Post-mitigation testing: after a mitigation system is installed, a follow-up test must be conducted at least 24 hours after system start-up and within 30 days of installation, using a minimum 48-hour test; results should be below 4 pCi/L (and ideally below 2 pCi/L).

If a short-term test result is 4 pCi/L or higher, a follow-up test is required: either a second short-term test (2-90 days) or a long-term test (more than 90 days); the average of the two short-term tests or the long-term result determines whether mitigation is recommended.

For real-estate transactions, if the first short-term test is 4 pCi/L or higher, a second short-term test should be conducted immediately, and the average of the two tests is used to decide whether mitigation is needed.

Mitigation decision: if the average of two short-term tests or a long-term test is 4 pCi/L or higher, mitigation is recommended; if the result is between 2 and 4 pCi/L, consider mitigation and retest periodically.

When a radon mitigation system is installed, the professional should verify that the system is functioning (fan operating, pressure field extension, and post-mitigation test) and provide the client with a completed system label and operation/maintenance instructions.

For schools and large buildings, testing should be conducted in all frequently occupied rooms in contact with the ground, and in rooms above unoccupied spaces; if any room tests at 4 pCi/L or higher, follow-up testing and mitigation are recommended.

Closed-building conditions must be documented: windows and doors closed (except for normal entry/exit), no whole-house or window fans operating, and normal HVAC operation; deviations should be noted in the report and may invalidate the test.

Health risk: radon is the second leading cause of lung cancer after smoking and the leading cause among non-smokers; the risk increases with exposure concentration and duration, and the EPA estimates that about 21,000 lung cancer deaths per year in the U.S. are radon-related.

The alpha particles from radon progeny deposit energy in the bronchial epithelium; the dose is driven by progeny concentration (WL), not radon gas alone, which is why the equilibrium ratio matters for interpreting results.

Radon entry: soil gas enters through cracks in the foundation, sump pits, floor drains, and gaps around pipes; the driving forces are the stack effect (pressure difference due to temperature), wind, and mechanical exhaust.

Building pressure: exhaust fans, dryers, and fireplaces can depressurize a house and increase radon entry; a mitigation system uses a sub-slab depressurization fan to reverse the pressure gradient and vent soil gas above the roof.

Seasonal and daily variation: radon concentrations typically peak in winter (stack effect strongest) and vary with weather (low pressure systems, rain, and snow cover can increase indoor radon); a single short-term test may not represent annual average.

The EPA action level of 4 pCi/L is not a health-based threshold; it is a practical action level, and the EPA recommends considering mitigation at 2-4 pCi/L because there is no known safe level of radon exposure.

Radon decay products: Po-218 and Po-214 are the alpha emitters; Pb-214 and Bi-214 are beta/gamma emitters; the progeny reach equilibrium with radon in about 3-4 hours in closed conditions.

Measurement physics: charcoal devices adsorb radon by diffusion and are analyzed by gamma spectroscopy or liquid scintillation; alpha-track detectors use a plastic film that records alpha tracks, which are counted after chemical etching.

The EPA's Indoor Radon Abatement Act (1988) and the Radon Measurement Proficiency (RMP) program established the framework for proficiency testing; the current proficiency programs are NRPP (National Radon Proficiency Program) and NRSB (National Radon Safety Board).

Certification requires passing an exam, maintaining continuing education (typically 8-16 hours per 2-year cycle depending on the program), and complying with the program's quality assurance and ethics requirements.

The Radon Measurement Professional must follow the EPA's Protocols for Radon and Radon Decay Product Measurements in Homes (EPA 402-R-92-003) and the EPA's Residential Measurement Protocol; these define closed-building conditions, placement, and QA requirements.

Disclosure: in real-estate transactions, the measurement professional must disclose any business relationship with a mitigation contractor and must not condition the test result on the sale of mitigation services.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years (or as required by the certification program), and make them available to the certification body upon request.

Liability: the measurement professional is responsible for the accuracy of the test and must not alter results; reporting a result below the LLD as zero or failing to report a result above the action level is a violation of professional standards.

State regulations: some states (e.g., New Jersey, Pennsylvania, Florida) have their own radon certification and reporting requirements that may be stricter than the EPA protocols; the professional must comply with the state in which the test is conducted.

Conflict of interest: a measurement professional should not perform mitigation on the same property within a specified period (often 1 year) unless disclosed, and should not use test results to pressure a client into purchasing mitigation services.

Device deployment: place the device in the lowest livable level, at least 20 inches above the floor, 12 inches from exterior walls, and 4 inches from other objects; avoid areas with high humidity, drafts, or direct sunlight.

Charcoal device handling: open the device only at the test location, record the exact start time, and reseal immediately at the end of the exposure period; exposure time must match the device's specified range (typically 2-7 days).

CRM deployment: place the monitor in the lowest livable level, verify it is functioning and calibrated, and record hourly data; the monitor should be placed on a stable surface and not moved during the test.

Chain of custody: record device serial numbers, deployment and retrieval dates/times, location, and the name of the person who deployed and retrieved the device; ship samples to the lab within the device's hold time.

Interference: if the occupant reports opening windows or using exhaust fans during the test, the test may be invalid; document the interference and consider retesting.

Quality assurance: deploy duplicates and blanks as required, and ensure that at least 10% of devices are duplicates and 5% are blanks (or the minimum specified by the certification program).

Post-test: report results to the client within the timeframe specified by the contract (typically 5-10 business days), and include the test method, dates, and the EPA action level.

Safety: radon test devices pose minimal risk to the professional; however, charcoal devices should be handled to avoid contamination, and CRM calibration sources should be handled according to the manufacturer's instructions.

Result interpretation: a result below 2 pCi/L is low; 2-4 pCi/L is a consideration zone; 4 pCi/L or higher requires follow-up testing and mitigation is recommended if confirmed.

Averaging: when two short-term tests are conducted, the average is used to decide whether mitigation is needed; if the two results differ by more than a factor of 2, consider a third test or a long-term test.

Uncertainty: report results with the device's uncertainty (typically +/- 10-25%); a result of 4.0 pCi/L with a 25% uncertainty could be as low as 3.0 pCi/L, which is why follow-up testing is recommended.

Client communication: explain that radon is a health risk, that the action level is 4 pCi/L, and that mitigation is recommended at or above that level; avoid alarming language and provide the EPA's consumer guidance.

Follow-up testing: if the initial test is 4 pCi/L or higher, recommend a second short-term test or a long-term test; if the average of two short-term tests is 4 pCi/L or higher, recommend mitigation.

Mitigation options: sub-slab depressurization, drain tile depressurization, block wall depressurization, and sub-membrane depressurization for crawl spaces; the professional should refer the client to a certified mitigation contractor.

Documentation: provide the client with a written report that includes the test method, dates, results, QA information, and the recommendation; retain a copy for at least 3 years.

Ethics: do not guarantee a specific result, do not pressure the client to mitigate, and do not perform mitigation on the same property without disclosure and compliance with state regulations.

Activated charcoal adsorption: passive device, 2-7 day exposure, analyzed by gamma spectroscopy or liquid scintillation; sensitive to temperature and humidity, so devices must be placed in conditioned spaces.

Alpha-track detector (ATD): passive device, 1-12 month exposure, plastic film etched and counted; not sensitive to humidity, suitable for long-term tests; LLD typically 0.3-1.0 pCi/L.

Electret ion chamber (EIC): passive device, short- or long-term, uses a charged electret whose voltage drop is proportional to radon exposure; requires voltage measurement before and after exposure.

Continuous radon monitor (CRM): active device, records hourly radon concentrations, provides short-term results and tamper detection; requires annual calibration and daily function checks.

Charcoal liquid scintillation (LS): charcoal device analyzed by liquid scintillation counting; provides short-term results and is sensitive to humidity.

Radon progeny measurement: uses a filter to collect progeny and a detector to measure alpha activity; working level (WL) is calculated from the progeny concentration, and the equilibrium ratio is used to estimate radon concentration.

Instrument selection: choose the method based on test duration, required sensitivity, and the client's needs; short-term tests use charcoal or CRM, long-term tests use ATD or EIC.

Calibration: all devices must be calibrated according to the manufacturer's instructions and the certification program's requirements; CRM calibration is typically annual, and passive devices are calibrated by the manufacturer.

Sub-slab depressurization (SSD): the most common mitigation method; a fan draws soil gas from beneath the slab and vents it above the roof; the system should create a negative pressure field beneath the slab.

Drain tile depressurization: used when a drain tile system is present; the fan is connected to the drain tile and vents soil gas above the roof.

Block wall depressurization: used for hollow block foundation walls; the fan draws air from the block wall cavities and vents it above the roof.

Sub-membrane depressurization: used for crawl spaces; a membrane is placed over the soil and the fan draws soil gas from beneath the membrane.

Post-mitigation testing: conduct a test at least 24 hours after system start-up and within 30 days of installation; the result should be below 4 pCi/L and ideally below 2 pCi/L.

System verification: check that the fan is operating, the pressure field is established, and the system label is affixed; provide the client with operation and maintenance instructions.

Maintenance: the system should be inspected annually, and the fan should be checked for operation; the client should be advised to retest every 2 years.

Communication: explain the mitigation system to the client, including the fan location, vent location, and the need for annual maintenance; provide a copy of the post-mitigation test report.

Certification: maintain certification through NRPP or NRSB, complete continuing education (typically 8-16 hours per 2-year cycle), and comply with the program's code of ethics.

Continuing education: courses should cover radon measurement, mitigation, health effects, and regulations; the professional should keep records of completed courses.

Code of ethics: provide accurate results, avoid conflicts of interest, maintain confidentiality, and comply with all applicable laws and regulations.

Professional development: stay current with EPA protocols, state regulations, and new measurement technologies; participate in proficiency testing programs.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years; make them available to the certification body upon request.

Client communication: provide clear, accurate information about radon risks and mitigation options; avoid guaranteeing specific results or pressuring clients.

Liability: the professional is responsible for the accuracy of the test and must not alter results; reporting a result below the LLD as zero or failing to report a result above the action level is a violation.

State regulations: comply with the state in which the test is conducted; some states have stricter requirements than the EPA protocols.

Real-estate test: conduct the test in the lowest livable level, with the building closed for 12 hours before the test starts, and the test must last at least 48 hours; the test should be conducted by a certified professional.

Disclosure: the measurement professional must disclose any business relationship with a mitigation contractor and must not condition the test result on the sale of mitigation services.

Follow-up: if the first short-term test is 4 pCi/L or higher, a second short-term test should be conducted immediately, and the average of the two tests is used to decide whether mitigation is needed.

Timing: the test should be conducted before the sale is finalized, and the results should be provided to the buyer and seller; the test should not be conducted during a real-estate transaction if the building is not in closed-building conditions.

Relocation testing: for relocation companies, the test should follow the same protocol as a real-estate test, and the results should be provided to the relocation company and the client.

Documentation: provide a written report that includes the test method, dates, results, QA information, and the recommendation; retain a copy for at least 3 years.

Ethics: do not guarantee a specific result, do not pressure the client to mitigate, and do not perform mitigation on the same property without disclosure and compliance with state regulations.

Communication: explain the results to the client in clear language, including the action level and the recommendation for follow-up testing or mitigation.

QA program: a written QA plan that includes device calibration, duplicate and blank measurements, spike tests, and recordkeeping.

Duplicates: at least 10% of deployed devices or 50 per year, whichever is smaller; RPD between duplicates typically within 25% for charcoal and 20% for alpha-track.

Blanks: at least 5% of deployed devices or 25 per year, whichever is smaller; blank results should be below the device's LLD.

Spikes: at least 3 spiked devices per 100 deployed devices (or 3 per year for low-volume testers); results should be within +/- 25% of the known value (or +/- 10% for CRM calibration checks).

Calibration: all devices must be calibrated according to the manufacturer's instructions and the certification program's requirements; CRM calibration is typically annual.

Recordkeeping: retain QA records, calibration records, and test records for at least 3 years; make them available to the certification body upon request.

Corrective action: if QA results are outside acceptable limits, investigate the cause, correct the problem, and document the corrective action.

Proficiency testing: participate in the certification program's proficiency testing program and maintain a passing score.

Radon is the second leading cause of lung cancer after smoking and the leading cause among non-smokers; the EPA estimates about 21,000 lung cancer deaths per year in the U.S. are radon-related.

Risk increases with exposure concentration and duration; there is no known safe level of radon exposure, which is why the EPA recommends considering mitigation at 2-4 pCi/L.

The alpha particles from radon progeny deposit energy in the bronchial epithelium; the dose is driven by progeny concentration (WL), not radon gas alone.

Smoking and radon exposure act synergistically; smokers exposed to radon have a much higher lung cancer risk than non-smokers exposed to the same radon level.

Risk communication: explain the risk in clear, non-alarming language, provide the EPA's consumer guidance, and avoid guaranteeing specific results.

Action level: the EPA action level of 4 pCi/L is not a health-based threshold; it is a practical action level, and the EPA recommends considering mitigation at 2-4 pCi/L.

Follow-up testing: if the initial test is 4 pCi/L or higher, recommend a second short-term test or a long-term test; if the average of two short-term tests is 4 pCi/L or higher, recommend mitigation.

Mitigation: refer the client to a certified mitigation contractor and explain the mitigation options (SSD, drain tile, block wall, sub-membrane).

Radon entry: soil gas enters through cracks in the foundation, sump pits, floor drains, and gaps around pipes; the driving forces are the stack effect, wind, and mechanical exhaust.

Stack effect: warm indoor air rises and escapes through the upper floors, creating a negative pressure in the lower levels that draws soil gas in; the effect is strongest in winter.

Depressurization: exhaust fans, dryers, and fireplaces can depressurize a house and increase radon entry; a mitigation system uses a sub-slab depressurization fan to reverse the pressure gradient.

Building pressure: the pressure difference between the soil and the indoor air drives radon entry; a mitigation system should create a negative pressure field beneath the slab.

Foundation types: basements, crawl spaces, and slab-on-grade foundations all can have radon entry; the mitigation method depends on the foundation type.

HVAC: normal HVAC operation should be maintained during a test, but exhaust fans and whole-house fans should not be operated during the closed-building period.

Weather: low pressure systems, rain, and snow cover can increase indoor radon; a single short-term test may not represent the annual average.

Mitigation: sub-slab depressurization, drain tile depressurization, block wall depressurization, and sub-membrane depressurization for crawl spaces.

Uncertainty: report results with the device's uncertainty (typically +/- 10-25%); a result of 4.0 pCi/L with a 25% uncertainty could be as low as 3.0 pCi/L.

Averaging: when two short-term tests are conducted, the average is used to decide whether mitigation is needed; if the two results differ by more than a factor of 2, consider a third test or a long-term test.

LLD: the lower limit of detection is the lowest concentration that can be reliably detected; results below the LLD should be reported as less than that value, not as zero.

Precision: duplicates assess precision; RPD between duplicates typically within 25% for charcoal and 20% for alpha-track.

Accuracy: spikes assess accuracy; results should be within +/- 25% of the known value (or +/- 10% for CRM calibration checks).

Statistical significance: a single short-term test may not be statistically representative of the annual average; long-term tests are preferred for decision-making.

Reporting: report results in pCi/L (or Bq/m3) and include the uncertainty and the LLD.

Data interpretation: a result below 2 pCi/L is low; 2-4 pCi/L is a consideration zone; 4 pCi/L or higher requires follow-up testing.

EPA protocols: the EPA's Protocols for Radon and Radon Decay Product Measurements in Homes (EPA 402-R-92-003) and the Residential Measurement Protocol define closed-building conditions, placement, and QA requirements.

Certification: NRPP and NRSB are the current proficiency programs; certification requires passing an exam, maintaining continuing education, and complying with the program's QA and ethics requirements.

State regulations: some states (e.g., New Jersey, Pennsylvania, Florida) have their own radon certification and reporting requirements that may be stricter than the EPA protocols.

Disclosure: in real-estate transactions, the measurement professional must disclose any business relationship with a mitigation contractor and must not condition the test result on the sale of mitigation services.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years (or as required by the certification program).

Liability: the measurement professional is responsible for the accuracy of the test and must not alter results.

Conflict of interest: a measurement professional should not perform mitigation on the same property within a specified period (often 1 year) unless disclosed.

Continuing education: complete 8-16 hours per 2-year cycle depending on the program; courses should cover radon measurement, mitigation, health effects, and regulations.

Placement: 20 inches above the floor, 12 inches from exterior walls, 4 inches from other objects, 3 feet from windows, doors, or vents; avoid bathrooms, kitchens, laundry rooms, closets, and crawl spaces.

Charcoal: open the device only at the test location, record the exact start time, and reseal immediately at the end of the exposure period; exposure time must match the device's specified range.

CRM: place the monitor in the lowest livable level, verify it is functioning and calibrated, and record hourly data; the monitor should be placed on a stable surface and not moved during the test.

Chain of custody: record device serial numbers, deployment and retrieval dates/times, location, and the name of the person who deployed and retrieved the device.

Interference: if the occupant reports opening windows or using exhaust fans during the test, the test may be invalid; document the interference and consider retesting.

QA: deploy duplicates and blanks as required; at least 10% duplicates and 5% blanks (or the minimum specified by the certification program).

Reporting: report results to the client within the timeframe specified by the contract (typically 5-10 business days).

Safety: handle charcoal devices to avoid contamination; handle CRM calibration sources according to the manufacturer's instructions.

Client communication: explain that radon is a health risk, that the action level is 4 pCi/L, and that mitigation is recommended at or above that level; avoid alarming language.

Follow-up: if the initial test is 4 pCi/L or higher, recommend a second short-term test or a long-term test; if the average of two short-term tests is 4 pCi/L or higher, recommend mitigation.

Mitigation: refer the client to a certified mitigation contractor and explain the mitigation options (SSD, drain tile, block wall, sub-membrane).

Documentation: provide a written report that includes the test method, dates, results, QA information, and the recommendation; retain a copy for at least 3 years.

Ethics: do not guarantee a specific result, do not pressure the client to mitigate, and do not perform mitigation on the same property without disclosure.

Confidentiality: maintain the confidentiality of client information and test results.

Conflict of interest: disclose any business relationship with a mitigation contractor and do not condition the test result on the sale of mitigation services.

Professional development: stay current with EPA protocols, state regulations, and new measurement technologies.

Activated charcoal: passive, 2-7 day exposure, analyzed by gamma spectroscopy or liquid scintillation; sensitive to temperature and humidity.

Alpha-track: passive, 1-12 month exposure, plastic film etched and counted; not sensitive to humidity, suitable for long-term tests.

Electret ion chamber: passive, short- or long-term, uses a charged electret whose voltage drop is proportional to radon exposure.

CRM: active, records hourly radon concentrations, provides short-term results and tamper detection; requires annual calibration and daily function checks.

Charcoal liquid scintillation: charcoal device analyzed by liquid scintillation counting; provides short-term results and is sensitive to humidity.

Radon progeny measurement: uses a filter to collect progeny and a detector to measure alpha activity; WL is calculated from the progeny concentration.

Instrument selection: choose the method based on test duration, required sensitivity, and the client's needs.

Calibration: all devices must be calibrated according to the manufacturer's instructions and the certification program's requirements.

Sub-slab depressurization: the most common mitigation method; a fan draws soil gas from beneath the slab and vents it above the roof.

Drain tile depressurization: used when a drain tile system is present; the fan is connected to the drain tile and vents soil gas above the roof.

Block wall depressurization: used for hollow block foundation walls; the fan draws air from the block wall cavities and vents it above the roof.

Sub-membrane depressurization: used for crawl spaces; a membrane is placed over the soil and the fan draws soil gas from beneath the membrane.

Post-mitigation testing: conduct a test at least 24 hours after system start-up and within 30 days of installation; the result should be below 4 pCi/L.

System verification: check that the fan is operating, the pressure field is established, and the system label is affixed.

Maintenance: the system should be inspected annually, and the fan should be checked for operation; the client should be advised to retest every 2 years.

Communication: explain the mitigation system to the client, including the fan location, vent location, and the need for annual maintenance.

Certification: maintain certification through NRPP or NRSB, complete continuing education (typically 8-16 hours per 2-year cycle), and comply with the program's code of ethics.

Continuing education: courses should cover radon measurement, mitigation, health effects, and regulations; keep records of completed courses.

Code of ethics: provide accurate results, avoid conflicts of interest, maintain confidentiality, and comply with all applicable laws and regulations.

Professional development: stay current with EPA protocols, state regulations, and new measurement technologies; participate in proficiency testing programs.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years.

Client communication: provide clear, accurate information about radon risks and mitigation options.

Liability: the professional is responsible for the accuracy of the test and must not alter results.

State regulations: comply with the state in which the test is conducted; some states have stricter requirements than the EPA protocols.

Real-estate test: conduct the test in the lowest livable level, with the building closed for 12 hours before the test starts, and the test must last at least 48 hours.

Disclosure: the measurement professional must disclose any business relationship with a mitigation contractor and must not condition the test result on the sale of mitigation services.

Follow-up: if the first short-term test is 4 pCi/L or higher, a second short-term test should be conducted immediately, and the average of the two tests is used.

Timing: the test should be conducted before the sale is finalized, and the results should be provided to the buyer and seller.

Relocation testing: for relocation companies, the test should follow the same protocol as a real-estate test.

Documentation: provide a written report that includes the test method, dates, results, QA information, and the recommendation.

Ethics: do not guarantee a specific result, do not pressure the client to mitigate, and do not perform mitigation on the same property without disclosure.

Communication: explain the results to the client in clear language, including the action level and the recommendation.

QA program: a written QA plan that includes device calibration, duplicate and blank measurements, spike tests, and recordkeeping.

Duplicates: at least 10% of deployed devices or 50 per year, whichever is smaller; RPD between duplicates typically within 25% for charcoal and 20% for alpha-track.

Blanks: at least 5% of deployed devices or 25 per year, whichever is smaller; blank results should be below the device's LLD.

Spikes: at least 3 spiked devices per 100 deployed devices (or 3 per year for low-volume testers); results should be within +/- 25% of the known value.

Calibration: all devices must be calibrated according to the manufacturer's instructions and the certification program's requirements.

Recordkeeping: retain QA records, calibration records, and test records for at least 3 years.

Corrective action: if QA results are outside acceptable limits, investigate the cause, correct the problem, and document the corrective action.

Proficiency testing: participate in the certification program's proficiency testing program and maintain a passing score.

Radon is the second leading cause of lung cancer after smoking and the leading cause among non-smokers; the EPA estimates about 21,000 lung cancer deaths per year in the U.S. are radon-related.

Risk increases with exposure concentration and duration; there is no known safe level of radon exposure.

The alpha particles from radon progeny deposit energy in the bronchial epithelium; the dose is driven by progeny concentration (WL), not radon gas alone.

Smoking and radon exposure act synergistically; smokers exposed to radon have a much higher lung cancer risk than non-smokers.

Risk communication: explain the risk in clear, non-alarming language, provide the EPA's consumer guidance, and avoid guaranteeing specific results.

Action level: the EPA action level of 4 pCi/L is not a health-based threshold; it is a practical action level.

Follow-up testing: if the initial test is 4 pCi/L or higher, recommend a second short-term test or a long-term test.

Mitigation: refer the client to a certified mitigation contractor and explain the mitigation options.

Radon entry: soil gas enters through cracks in the foundation, sump pits, floor drains, and gaps around pipes; the driving forces are the stack effect, wind, and mechanical exhaust.

Stack effect: warm indoor air rises and escapes through the upper floors, creating a negative pressure in the lower levels that draws soil gas in.

Depressurization: exhaust fans, dryers, and fireplaces can depressurize a house and increase radon entry.

Building pressure: the pressure difference between the soil and the indoor air drives radon entry; a mitigation system should create a negative pressure field beneath the slab.

Foundation types: basements, crawl spaces, and slab-on-grade foundations all can have radon entry.

HVAC: normal HVAC operation should be maintained during a test, but exhaust fans and whole-house fans should not be operated during the closed-building period.

Weather: low pressure systems, rain, and snow cover can increase indoor radon.

Mitigation: sub-slab depressurization, drain tile depressurization, block wall depressurization, and sub-membrane depressurization for crawl spaces.

Uncertainty: report results with the device's uncertainty (typically +/- 10-25%).

Averaging: when two short-term tests are conducted, the average is used to decide whether mitigation is needed.

LLD: the lower limit of detection is the lowest concentration that can be reliably detected; results below the LLD should be reported as less than that value.

Precision: duplicates assess precision; RPD between duplicates typically within 25% for charcoal and 20% for alpha-track.

Accuracy: spikes assess accuracy; results should be within +/- 25% of the known value.

Statistical significance: a single short-term test may not be statistically representative of the annual average.

Reporting: report results in pCi/L (or Bq/m3) and include the uncertainty and the LLD.

Data interpretation: a result below 2 pCi/L is low; 2-4 pCi/L is a consideration zone; 4 pCi/L or higher requires follow-up testing.

EPA protocols: the EPA's Protocols for Radon and Radon Decay Product Measurements in Homes (EPA 402-R-92-003) and the Residential Measurement Protocol define closed-building conditions, placement, and QA requirements.

Certification: NRPP and NRSB are the current proficiency programs; certification requires passing an exam, maintaining continuing education, and complying with the program's QA and ethics requirements.

State regulations: some states have their own radon certification and reporting requirements that may be stricter than the EPA protocols.

Disclosure: in real-estate transactions, the measurement professional must disclose any business relationship with a mitigation contractor.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years.

Liability: the measurement professional is responsible for the accuracy of the test and must not alter results.

Conflict of interest: a measurement professional should not perform mitigation on the same property within a specified period (often 1 year) unless disclosed.

Continuing education: complete 8-16 hours per 2-year cycle depending on the program.

Placement: 20 inches above the floor, 12 inches from exterior walls, 4 inches from other objects, 3 feet from windows, doors, or vents.

Charcoal: open the device only at the test location, record the exact start time, and reseal immediately at the end of the exposure period.

CRM: place the monitor in the lowest livable level, verify it is functioning and calibrated, and record hourly data.

Chain of custody: record device serial numbers, deployment and retrieval dates/times, location, and the name of the person who deployed and retrieved the device.

Interference: if the occupant reports opening windows or using exhaust fans during the test, the test may be invalid.

QA: deploy duplicates and blanks as required; at least 10% duplicates and 5% blanks.

Reporting: report results to the client within the timeframe specified by the contract.

Safety: handle charcoal devices to avoid contamination; handle CRM calibration sources according to the manufacturer's instructions.

Client communication: explain that radon is a health risk, that the action level is 4 pCi/L, and that mitigation is recommended at or above that level.

Follow-up: if the initial test is 4 pCi/L or higher, recommend a second short-term test or a long-term test.

Mitigation: refer the client to a certified mitigation contractor and explain the mitigation options.

Documentation: provide a written report that includes the test method, dates, results, QA information, and the recommendation.

Ethics: do not guarantee a specific result, do not pressure the client to mitigate, and do not perform mitigation on the same property without disclosure.

Confidentiality: maintain the confidentiality of client information and test results.

Conflict of interest: disclose any business relationship with a mitigation contractor.

Professional development: stay current with EPA protocols, state regulations, and new measurement technologies.

Activated charcoal: passive, 2-7 day exposure, analyzed by gamma spectroscopy or liquid scintillation.

Alpha-track: passive, 1-12 month exposure, plastic film etched and counted.

Electret ion chamber: passive, short- or long-term, uses a charged electret whose voltage drop is proportional to radon exposure.

CRM: active, records hourly radon concentrations, provides short-term results and tamper detection.

Charcoal liquid scintillation: charcoal device analyzed by liquid scintillation counting.

Radon progeny measurement: uses a filter to collect progeny and a detector to measure alpha activity.

Instrument selection: choose the method based on test duration, required sensitivity, and the client's needs.

Calibration: all devices must be calibrated according to the manufacturer's instructions and the certification program's requirements.

Sub-slab depressurization: the most common mitigation method; a fan draws soil gas from beneath the slab and vents it above the roof.

Drain tile depressurization: used when a drain tile system is present; the fan is connected to the drain tile and vents soil gas above the roof.

Block wall depressurization: used for hollow block foundation walls; the fan draws air from the block wall cavities and vents it above the roof.

Sub-membrane depressurization: used for crawl spaces; a membrane is placed over the soil and the fan draws soil gas from beneath the membrane.

Post-mitigation testing: conduct a test at least 24 hours after system start-up and within 30 days of installation.

System verification: check that the fan is operating, the pressure field is established, and the system label is affixed.

Maintenance: the system should be inspected annually, and the fan should be checked for operation.

Communication: explain the mitigation system to the client, including the fan location, vent location, and the need for annual maintenance.

Certification: maintain certification through NRPP or NRSB, complete continuing education (typically 8-16 hours per 2-year cycle), and comply with the program's code of ethics.

Continuing education: courses should cover radon measurement, mitigation, health effects, and regulations.

Code of ethics: provide accurate results, avoid conflicts of interest, maintain confidentiality, and comply with all applicable laws and regulations.

Professional development: stay current with EPA protocols, state regulations, and new measurement technologies.

Recordkeeping: retain test records, QA results, and calibration records for at least 3 years.

Client communication: provide clear, accurate information about radon risks and mitigation options.

Liability: the professional is responsible for the accuracy of the test and must not alter results.

State regulations: comply with the state in which the test is conducted; some states have stricter requirements than the EPA protocols.