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 is the minimum number of post-mitigation radon tests required before issuing a compliance certificate under most state programs? → One short-term or long-term test
2. What are the key health concerns associated with radon exposure? → Increased risk of lung cancer
3. What is the recommended placement for a post-mitigation radon test device? → Lowest livable area, at least 20 inches above the floor
4. What is a sub-slab depressurization system? → A system that vents radon from beneath the building using pipes
5. What is the purpose of sealing slab penetrations and expansion joints in a commercial mitigation project? → To reduce radon entry pathways and improve system efficiency
6. When working in a confined space during radon mitigation, what OSHA standard primarily governs entry procedures? → 29 CFR 1910.146 (Permit-Required Confined Spaces)
7. Which document is required before beginning radon mitigation work in a commercial building in most U.S. jurisdictions? → A building permit
8. What role does sub-slab ventilation play in radon mitigation? → It helps vent radon from beneath the foundation
9. Which type of radon testing device provides immediate results? → Active radon detectors
10. 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
11. What is the recommended safety measure when working with radon mitigation systems in confined spaces? → Proper ventilation and monitoring are crucial
12. What type of fan is typically used in residential radon mitigation systems? → Inline centrifugal fan rated for continuous operation
13. When an RMS moves to a new state, what is the first professional step they should take before performing mitigation work there? → Research and comply with the new state's specific radon contractor licensing requirements
14. 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
15. Which ethical principle requires an RMS to disclose a conflict of interest to a client? → Transparency and honesty
16. What is the function of a radon fan in a mitigation system? → To create negative pressure and vent radon outside
17. Which organization administers the most widely recognized RMS certification program in the United States? → AARST-NRPP
18. In a commercial building, where should the radon fan discharge point be located? → At least 10 feet above grade and away from windows and air intakes
19. A post-mitigation test result shows 3.8 pCi/L. What is the most appropriate next step? → Discuss system optimization options with the homeowner
20. Under EPA guidelines, what is the maximum acceptable radon level in a home before mitigation is strongly recommended? → 4 pCi/L
21. What is a common challenge with ventilation systems in radon mitigation? → Ensuring the system is strong enough to remove radon but not too strong
22. How many continuing education hours does NRPP typically require for RMS certification renewal each cycle? → 24 hours
23. 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
24. What is the purpose of maintaining a client file for at least 5–7 years after a mitigation job? → To support warranty claims, regulatory audits, and professional liability defense
25. How often should post-mitigation radon levels be retested? → Every 2 years, or after significant building changes
26. An RMS is asked to provide a written proposal for a mitigation job. Which element is MOST critical to include? → Scope of work, cost, and post-mitigation testing plan
27. A smoke pencil or puffer is used during radon diagnostic testing primarily to: → Identify air pathways and verify airflow direction around the foundation
28. What is the primary goal of health and safety regulations in radon mitigation? → To ensure safe and effective radon mitigation
29. A client asks an RMS to certify a mitigation system installed by an uncertified contractor. What should the RMS do? → Refuse and explain ethical and legal obligations
30. A diagnostic pressure field extension test in a commercial building shows less than -1 Pa at 10 feet from the suction point. What does this indicate? → Sub-slab communication is poor and additional suction points are needed