RMS Cheat Sheet 2026

The 30 highest-yield RMS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What are the key health concerns associated with radon exposure? → Increased risk of lung cancer
2. What is the recommended placement for a post-mitigation radon test device? → Lowest livable area, at least 20 inches above the floor
3. What is a sub-slab depressurization system? → A system that vents radon from beneath the building using pipes
4. What role does sub-slab ventilation play in radon mitigation? → It helps vent radon from beneath the foundation
5. Which type of radon testing device provides immediate results? → Active radon detectors
6. What is the primary purpose of performing diagnostic testing before installing a radon mitigation system? → To determine optimal sub-slab communication and suction point locations
7. If a mitigation system test pipe shows no pressure differential when the fan is running, what should be checked first? → Whether the suction pit properly connects to the sub-slab environment
8. What is the recommended safety measure when working with radon mitigation systems in confined spaces? → Proper ventilation and monitoring are crucial
9. What type of fan is typically used in residential radon mitigation systems? → Inline centrifugal fan rated for continuous operation
10. During diagnostic testing of a slab-on-grade home, a technician notices that a floor drain is open to the sub-slab area. What is the appropriate response? → Identify it as a potential radon bypass pathway and address it in the mitigation plan
11. A diagnostic test reveals very low sub-slab airflow despite a high-powered fan. What is the most likely cause? → The sub-slab fill has very low permeability such as clay or fine sand
12. What does a U-tube manometer permanently installed on a mitigation system allow a homeowner to monitor? → Whether the fan is maintaining negative pressure in the suction pipe
13. What is the function of a radon fan in a mitigation system? → To create negative pressure and vent radon outside
14. What is a common challenge with ventilation systems in radon mitigation? → Ensuring the system is strong enough to remove radon but not too strong
15. Why is it important to monitor radon levels during and after the installation of a mitigation system? → To ensure the system is effectively reducing radon
16. How often should post-mitigation radon levels be retested? → Every 2 years, or after significant building changes
17. A smoke pencil or puffer is used during radon diagnostic testing primarily to: → Identify air pathways and verify airflow direction around the foundation
18. What is the primary goal of health and safety regulations in radon mitigation? → To ensure safe and effective radon mitigation
19. What should be done after a radon mitigation system is installed? → Test radon levels again to ensure effectiveness
20. How does creating a sealed environment contribute to radon mitigation? → It creates an airtight environment that prevents radon from entering
21. Why is it essential to maintain a record of radon mitigation system installations? → For future inspections and compliance with regulations
22. How can natural ventilation systems contribute to radon mitigation? → It improves indoor air quality by allowing air exchange
23. What type of radon test provides the most accurate long-term average? → Alpha track detector deployed for 91 days to 1 year
24. What is the half-life of radon-222? → 3.8 days
25. Why is sealing cracks and gaps in a building important for radon mitigation? → It prevents radon from entering the building
26. What are the key components of a radon mitigation system? → Fan, pipes, suction point, and venting system
27. Which radon measurement technique is considered the most reliable for long-term testing? → Long-term testing with alpha track detectors
28. During a block-wall depressurization diagnostic, what is primarily being assessed? → Whether hollow cores in block walls can be depressurized as a radon entry pathway
29. What is the first step in designing a radon mitigation system for a building? → Test radon levels to assess the appropriate system
30. When should a contractor perform follow-up diagnostic verification after initial system installation? → As part of post-installation verification before final sign-off on the job