RADON MEASUREMENT PROFESSIONAL EXAM
(INTERNACHI AND AARST) QUESTIONS AND ANSWERS What
1. What soil characteristic most affects radon transport?
→ Permeability
2. What is the unit of radon concentration in air in the U.S.?
→ Picocuries per liter (pCi/L)
3. What is the EPA’s action level for radon?
→ 4.0 pCi/L
4. Which factor does NOT affect indoor radon levels?
→ Color of the walls
5. What is the source of radon in water supplies?
→ Groundwater from wells, especially in high-uranium areas
6. How is radon typically removed from water?
→ Aeration or granular activated carbon (GAC) treatment
7. What is the primary health risk from radon exposure?
→ Lung cancer
8. Which group is at the highest risk from radon exposure?
→ Smokers
9. What government agency classifies radon as a carcinogen?
→ EPA and WHO
10. What radon entry method involves pressure differences?
→ Soil gas infiltration due to stack effect
11. What is the stack effect?
→ Movement of air into buildings from the ground due to pressure differences.
12. In which regions of the U.S. are radon levels generally higher?
→ Northern and mountainous areas
13. Can radon be detected by smell or sight?
→ No
14. Is there a safe level of radon according to EPA?
→ No, any exposure carries risk.
21. What are the two main categories of radon measurement devices?
→ Passive and active
22. Name a common passive device.
→ Charcoal canister
23. Name a common active device.
→ Continuous Radon Monitor (CRM)
24. How long is a short-term radon test?
→ 2 to 90 days
25. How long is a long-term radon test?
→ More than 90 days
, 26. What is the minimum time for a short-term test in real estate?
→ 48 hours
27. What passive device provides a time-integrated result?
→ Alpha track detector
28. What device can measure hourly radon levels?
→ CRM (Continuous Radon Monitor)
29. What environmental condition must be recorded during testing?
→ Temperature, humidity, barometric pressure
30. Which radon detector requires laboratory analysis?
→ Charcoal canister, alpha track, electret ion chamber
31. What should you avoid near radon detectors during testing?
→ Fans, heaters, open windows
32. Why is closed-building condition important during testing?
→ To prevent dilution and ensure accurate readings
33. How do you calculate the average radon level over time?
→ Sum of readings divided by number of samples
34. What does a CRM use to detect radon?
→ Ionization or scintillation chambers
35. What’s the purpose of duplicate sampling?
→ Assess precision
36. What is a blank sample used for?
→ Detect contamination
37. What is a spike sample?
→ Device exposed to known radon concentration for calibration
38. How should a charcoal canister be positioned?
→ 20–48 inches above the floor
39. How far should the detector be from windows or vents?
→ At least 3 feet
40. What is the typical shelf life of a charcoal canister?
→ 5–7 days after opening
41. What causes back-diffusion in charcoal devices?
→ High humidity
42. How does an electret ion chamber work?
→ Measures voltage drop due to radon ionization
43. When should the test be invalidated?
→ If tampering or significant deviation from protocols is observed
44. What is the purpose of tamper indicators?
→ Detect interference or movement
45. Can you use a radon test during severe storms?
→ No, wait until stable conditions return
46. What is calibration?
→ Adjustment of equipment to a known standard
47. How often should CRM devices be calibrated?
→ Annually
48. What is the maximum relative humidity for charcoal tests?
→ Typically < 80%
(INTERNACHI AND AARST) QUESTIONS AND ANSWERS What
1. What soil characteristic most affects radon transport?
→ Permeability
2. What is the unit of radon concentration in air in the U.S.?
→ Picocuries per liter (pCi/L)
3. What is the EPA’s action level for radon?
→ 4.0 pCi/L
4. Which factor does NOT affect indoor radon levels?
→ Color of the walls
5. What is the source of radon in water supplies?
→ Groundwater from wells, especially in high-uranium areas
6. How is radon typically removed from water?
→ Aeration or granular activated carbon (GAC) treatment
7. What is the primary health risk from radon exposure?
→ Lung cancer
8. Which group is at the highest risk from radon exposure?
→ Smokers
9. What government agency classifies radon as a carcinogen?
→ EPA and WHO
10. What radon entry method involves pressure differences?
→ Soil gas infiltration due to stack effect
11. What is the stack effect?
→ Movement of air into buildings from the ground due to pressure differences.
12. In which regions of the U.S. are radon levels generally higher?
→ Northern and mountainous areas
13. Can radon be detected by smell or sight?
→ No
14. Is there a safe level of radon according to EPA?
→ No, any exposure carries risk.
21. What are the two main categories of radon measurement devices?
→ Passive and active
22. Name a common passive device.
→ Charcoal canister
23. Name a common active device.
→ Continuous Radon Monitor (CRM)
24. How long is a short-term radon test?
→ 2 to 90 days
25. How long is a long-term radon test?
→ More than 90 days
, 26. What is the minimum time for a short-term test in real estate?
→ 48 hours
27. What passive device provides a time-integrated result?
→ Alpha track detector
28. What device can measure hourly radon levels?
→ CRM (Continuous Radon Monitor)
29. What environmental condition must be recorded during testing?
→ Temperature, humidity, barometric pressure
30. Which radon detector requires laboratory analysis?
→ Charcoal canister, alpha track, electret ion chamber
31. What should you avoid near radon detectors during testing?
→ Fans, heaters, open windows
32. Why is closed-building condition important during testing?
→ To prevent dilution and ensure accurate readings
33. How do you calculate the average radon level over time?
→ Sum of readings divided by number of samples
34. What does a CRM use to detect radon?
→ Ionization or scintillation chambers
35. What’s the purpose of duplicate sampling?
→ Assess precision
36. What is a blank sample used for?
→ Detect contamination
37. What is a spike sample?
→ Device exposed to known radon concentration for calibration
38. How should a charcoal canister be positioned?
→ 20–48 inches above the floor
39. How far should the detector be from windows or vents?
→ At least 3 feet
40. What is the typical shelf life of a charcoal canister?
→ 5–7 days after opening
41. What causes back-diffusion in charcoal devices?
→ High humidity
42. How does an electret ion chamber work?
→ Measures voltage drop due to radon ionization
43. When should the test be invalidated?
→ If tampering or significant deviation from protocols is observed
44. What is the purpose of tamper indicators?
→ Detect interference or movement
45. Can you use a radon test during severe storms?
→ No, wait until stable conditions return
46. What is calibration?
→ Adjustment of equipment to a known standard
47. How often should CRM devices be calibrated?
→ Annually
48. What is the maximum relative humidity for charcoal tests?
→ Typically < 80%
