Radon testing and mitigation · licenses compared
Radon testing vs mitigation: who does which
Testing tells you the level. Mitigation is the system that lowers it. All three states license the two jobs separately, and the counts on their lists show how different the trades are.
Who holds each license today
| State list | Testing | Mitigation | Read |
|---|---|---|---|
| Illinois IEMA-OHS (people) | 484 | 138 | 2026-10-15 |
| Pennsylvania DEP (directory rows) | 659 | 137 | 2026-10-01 |
| Colorado DORA (active licenses) | 548 | 233 | 2026-10-15 |
In Illinois, 124 of the 306 radon measurement professionals also hold an active IDFPR home inspector license (first and last name matched across the two state lists, 2026-10-15). Mitigation is a trade of its own.
Testing
- Short-term: 2 to 90 days
- Short-term radon tests stay in the home for two to 90 days, depending on the device.U.S. Environmental Protection Agency, read October 15, 2026
- Long-term: over 90 days
- Long-term tests stay in the home for more than 90 days and usually use alpha track or electret ion chamber detectors.U.S. Environmental Protection Agency, read October 15, 2026
- Lowest lived-in level
- The test kit goes in the lowest lived-in level: the basement if it is used often, otherwise the first floor.U.S. Environmental Protection Agency, read October 15, 2026
Mitigation
- Vent pipe and fan system
- The main fix is a vent pipe and fan that pull radon from beneath the house and send it outside.U.S. Environmental Protection Agency, read October 15, 2026
- Use a qualified mitigator
- EPA recommends a certified or qualified radon mitigation contractor trained to fix radon problems.U.S. Environmental Protection Agency, read October 15, 2026
Why the two are kept apart
- Four individual license types
- IEMA-OHS issues four individual radon licenses: measurement professional, measurement technician, mitigation professional and mitigation technician. Laboratories are licensed separately.Illinois General Assembly, Joint Committee on Administrative Rules (Illinois Administrative Code), read October 15, 2026
- Mitigators cannot test own work
- A mitigator who also holds a measurement license may not do the before or after tests at a house where they installed the system, unless another independent person has measured.Illinois General Assembly, Joint Committee on Administrative Rules (Illinois Administrative Code), read October 15, 2026
- Independent post-fix tester
- EPA recommends the after-mitigation test be done by an independent, qualified radon tester.U.S. Environmental Protection Agency, read October 15, 2026
- Three separate certifications
- DEP certifies radon testing, radon mitigation and radon laboratory analysis separately, and each needs its own certification.Pennsylvania Department of Environmental Protection, read October 15, 2026
- Two license types
- Colorado issues two radon licenses, one for radon measurement professionals and one for radon mitigation professionals. Each requires proof of certification in that discipline from a proficiency program.Colorado General Assembly (Session Laws 2021, ch. 398, HB21-1195), read October 15, 2026
Home inspectors and radon tests
- Testers are often inspectors
- EPA notes that the qualified radon tester a buyer hires is very often a home inspector.U.S. Environmental Protection Agency, read October 15, 2026
- Home inspectors need the radon license
- A home inspector who runs radon tests for clients needs an IEMA-OHS measurement license. The only retail exemption excludes sellers that also serve the client through home inspection or real estate representation.Illinois General Assembly (Illinois Compiled Statutes), read October 15, 2026
- Placing a test device
- Anyone who places and retrieves a radon test device for someone else, such as a home inspector in a sale, must hold DEP testing certification.Pennsylvania Department of Environmental Protection, read October 15, 2026
Sources
- U.S. Environmental Protection Agency, read October 15, 2026.
- U.S. Environmental Protection Agency, read October 15, 2026.
- U.S. Environmental Protection Agency, read October 15, 2026.
- Illinois General Assembly, Joint Committee on Administrative Rules (Illinois Administrative Code), read October 15, 2026.
- Pennsylvania Department of Environmental Protection, read October 15, 2026.
- Colorado General Assembly (Session Laws 2021, ch. 398, HB21-1195), read October 15, 2026.
- Illinois General Assembly (Illinois Compiled Statutes), read October 15, 2026.
- State lists: IEMA-OHS Radon Active Licensee Listing; DEP Radon Services Directory; Professional and Occupational Licenses in Colorado (DORA, open data).