Radon Doesn't Care How Nice Your Basement Is

You can put in the home theater. The bar with the mini fridge. The home gym nobody uses after February. None of it matters to radon. It's not impressed by your renovation, and it's definitely not going to ring the doorbell before it shows up.

If you're not familiar, radon is a naturally occurring radioactive gas that comes from the slow decay of uranium in soil and rock. It's completely invisible, has no smell, and won't announce itself in any way you'd notice on your own. It seeps up out of the ground and into homes through foundation cracks, sump pits, slab joints, and anywhere else the earth and your basement happen to touch. The EPA considers it the second leading cause of lung cancer in the U.S. after smoking, which is a strange amount of danger to carry for something that just sits there quietly doing nothing visible.

Here's the part that surprises people: Indiana isn't a minor player here. Most of the state, including Marion County and the surrounding area, falls into the EPA's highest radon potential zone, largely thanks to the glacial soils left behind thousands of years ago. That means a brand-new build in a shiny new subdivision can test just as high as a hundred-year-old bungalow. Age and condition of the house tell you almost nothing about radon levels. In fact, newer homes built tighter for energy efficiency sometimes test higher, because there's less natural air movement to dilute whatever's seeping in from below.

I'll be honest: radon testing is the least dramatic part of my job. There's no flashlight work, no crawling through spider webs, no dramatic discovery to report. I set a small monitor on a shelf in the lowest livable level of the house, leave it alone for 48 hours, and come back to read a number. That's it. But it's also one of the few things I do where the "boring" part is exactly the point — you want a quiet, undisturbed measurement, not a performance.

A proper test means closed-house conditions (windows shut, normal HVAC operation) for at least 12 hours before and during testing, placed in the lowest level someone could reasonably use — a storage-only, never-visited sub-basement doesn't count. The EPA's action level is 4 picocuries per liter (pCi/L). Above that, mitigation is strongly recommended, not just mentioned in passing.

The good news is mitigation works, and it works fast. A sub-slab depressurization system — basically a sealed pipe and a quiet fan that pulls soil gas from underneath the slab and vents it safely above the roofline — typically brings levels down dramatically within a day of installation. It's installed by a certified radon mitigation contractor, not a general handyman, and it's a far smaller expense than most people assume going in.

For buyers: test during your inspection period. It's inexpensive insurance, and if levels come back high, mitigation is a very reasonable thing to negotiate into the deal rather than a reason to panic. For sellers: testing before you list means no surprises mid-contract, and a documented mitigation system already in place can actually be a selling point rather than a red flag.

Either way, it's not something you can eyeball, smell your way to, or guess based on how old or new the house looks. You test for it, or you don't know.

If you're buying, selling, or just haven't had your current home checked, we're happy to talk through what a radon test looks like alongside a full inspection. No pressure — just straightforward information so you know what you're dealing with. Reach out anytime to book an inspection with IH Inspections.