Post Mitigation Testing

Overview

This guide covers everything homeowners need to know about post mitigation testing. Whether you've just received a high test result, are evaluating whether to hire a contractor, or want to understand the technical process in detail, you'll find clear, actionable information here.

Key Points

• The EPA action level for radon is 4 pCi/L — at or above this level, mitigation is recommended.
• Always use NRPP or NRSB certified contractors, regardless of whether your state requires licensing.
• A post-mitigation test is required after any installation — it's the only way to confirm the system is working.
• Permit requirements vary by state and municipality. Most states do not require a statewide building permit, but electrical permits for the fan circuit are common.

Step-by-Step Process

1. Test your home using a certified radon test kit. Place at the lowest livable level under closed-house conditions for at least 48 hours.
2. Interpret your result. Use the test results guide or Action Level Advisor to understand what your pCi/L means.
3. Check your state's requirements for contractor certification and permits using the permit guide or your state page.
4. Hire a certified contractor. Get 2–3 quotes from NRPP or NRSB certified professionals. Review the contractor hiring guide for questions to ask.
5. Post-mitigation test. After 24–48 hours, run a new radon test to confirm the system has reduced levels to below 4 pCi/L.

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