Radon Testing in Indianapolis

Updated October 2026 · 4 public sources cited

IDOH says testing is the only way to know your radon level, and Marion County residents can ask the county health department for a free test. Here's how it works.

Your three options

• Marion County's free test. Request it through the county health department's Indoor Air Quality Program.¹
• A store or online kit. IDOH says kits cost $5–$30 and some add a lab fee when you mail them in. It also says your county health department may offer discounted kits.²
• A licensed tester. Indiana licenses primary testers, who may use continuous monitors, and secondary testers, who place and pick up passive kits. Both report results to IDOH each year.³

Placing the kit the IDOH way

• Read the kit's instructions and check the expiration date.²
• Test the lowest livable level, at least 20 inches off the floor, somewhere it won't be disturbed.²
• Keep it at least 3 feet from windows and exterior doors and away from kitchens, baths and laundry rooms.²
• Keep windows and outside doors closed for 12 hours before and during a short test.⁴

What to do with the number

IDOH highly recommends a mitigation system at or above 4 pCi/L.² EPA's sequence: confirm a high short-term result with a second test, long-term if you can wait, short-term again if you can't. Test again right away if the first reading is above 8. Mitigate if a long-term result, or the average of two short-term tests, is 4 or higher.⁴

How often to test

IDOH says all homes should be tested every 2 to 5 years, and again after any mitigation work.² Renovating a basement, adding an addition or replacing the HVAC can change how air moves, so a fresh test is worth it after big projects.⁴

Buying or selling in Indianapolis

For real estate transactions, IDOH says to test the lowest level that could be occupied.² When the inspection window is short, a licensed primary tester can run an active monitor, which secondary testers and homeowner kits can't.³

Please note: Indiana requires an Indiana Department of Health license to test or mitigate radon in homes. This page is general information summarized from public agencies, not professional advice. For advice about your home, talk with an IDOH-licensed radon professional.