1. The EPA action level for indoor radon at which mitigation is recommended is:
Answer & explanation
Answer: C. The EPA recommends mitigation at 4 pCi/L or higher. Radon is the second leading cause of lung cancer.
law
radon
Radon is a colorless, odorless, radioactive gas produced by the natural breakdown of uranium in soil and rock. It enters homes through cracks in foundations and basements and is a leading cause of lung cancer. Radon is detected only by testing, and high levels can usually be reduced with a mitigation system that vents gas from beneath the home. Disclosure and testing rules vary by state.
- Exam tip
- Radon cannot be seen or smelled, so testing is the only way to know. It is naturally occurring, unlike asbestos or lead paint, which come from building materials.
- Example
- A buyer's radon test shows 8 picocuries per liter in the basement, above the EPA action level of 4, so the seller agrees to install a mitigation fan.
Related terms & state variants
Sources
Source verification pending. Confirm current requirements with your state regulator.
Last verified: 2026-10-23