Central Iowa radon levels are the highest in the United States, and it is not close. The Iowa Radon Survey found 71.6% of Iowa homes test above the EPA action level of 4 pCi/L, and the average Iowa home measures roughly 8.5 pCi/L against a national average of 1.3. All 99 Iowa counties sit in EPA Zone 1, the highest-risk designation the agency assigns. If you are buying anywhere between Ankeny and Ames, the honest odds are that the house you are under contract on has a radon problem.
The good news is that radon is one of the cheapest, most solvable findings in an Iowa home inspection. Here is how testing actually works inside a Central Iowa purchase, what the law requires, and what it costs to fix.
Radon is a colorless, odorless radioactive gas produced as uranium in soil and rock breaks down. It enters a home through foundation cracks, sump pits, floor drains, and gaps around plumbing penetrations, then accumulates in the lowest occupied level. The EPA identifies radon as the leading cause of lung cancer among people who have never smoked.
Iowa's geology is the reason our numbers are so high. Glacial till deposited across the state carries uranium-bearing material, and our soils are permeable enough to let the gas migrate upward. That is a statewide condition, not a neighborhood condition. A 1950s ranch in Des Moines, a 2004 two-story in Johnston, and a brand-new build in Bondurant can all test high. Two houses on the same street can test very differently.
Which means one thing for buyers: you cannot infer a radon level from the age of the house, the price of the house, or the neighbor's test. The only way to know is to measure that specific home.
This is where buyers and sellers both tend to be surprised. Iowa Code Chapter 558A governs residential seller disclosure, and radon is built into it - but the requirement is disclosure, not testing.
So a seller who has never tested can honestly answer "no known tests" and be fully compliant. The disclosure statement is not a clean bill of health - it is a record of what the seller knows. If radon is going to get measured on the house you are buying, you are almost always the one who has to ask for it.
In a DMAAR or CIBR purchase agreement, radon testing belongs inside your inspection period, alongside the general home inspection. The mechanics:
One practical note on interpretation: 4 pCi/L is the EPA action level, not a safety line. The EPA is explicit that there is no risk-free level of radon and recommends that homeowners consider mitigation between 2 and 4 pCi/L as well. A result of 3.8 is not a pass - it is a judgment call, and a cheap one to resolve.
A radon mitigation system is straightforward construction: a sealed suction point in the slab or sump, PVC pipe routed to the roofline, and an inline fan that creates negative pressure under the foundation so the gas vents outside instead of inside. Published Iowa contractor pricing in 2026 runs roughly $800 to $2,500 for a typical installation, with most standard basements landing in the middle of that range. Complex foundations, crawl spaces, and multiple suction points push higher.
Post-mitigation, a good installer retests to confirm the system actually dropped the level, and most systems include a manometer so you can see at a glance that the fan is still pulling.
On who pays: this is a negotiated item, not a legal obligation, and in Central Iowa it is commonly resolved as a seller-paid mitigation or a closing-cost credit sized to the bid. Because the cost is small relative to the purchase price and the fix is permanent and documented, it tends to be one of the easier repair requests to get agreement on - particularly in a market where sellers are already granting concessions. What you want is the work completed by a credentialed mitigation specialist with a post-mitigation test in hand before closing, not a cash credit and a promise to deal with it later.
Investors and house hackers have two extra considerations.
Test every unit that touches the ground. In a duplex or fourplex, each ground-contact unit is its own air space with its own foundation penetrations. One low reading in unit A tells you very little about unit B. Testing all of them during the inspection period costs a fraction of one month's rent.
Understand your disclosure position as a landlord. Iowa's 558A disclosure duties attach to sales, not leases, but once you know a unit measures high you own that knowledge, and a tenant asking about air quality is entitled to a straight answer. The cleaner path is to mitigate before the first tenant moves in and treat the system as part of the asset - it is a one-time capital cost, it is a genuine differentiator in a rental listing, and it removes a future liability conversation entirely.
New construction is not automatically safe, but it is often cheaper to fix. Many Central Iowa builders now rough in passive radon systems - the pipe and the suction point are already there, unfanned. If your new build tests high, activating it can be a few hundred dollars rather than a full installation. Ask your builder in writing whether a passive system is included before you sign the addendum.
You do not need a transaction to test. Short-term test kits are widely available and inexpensive, and county public health departments across Central Iowa periodically offer free or reduced-cost kits. Test the lowest level you actually use - a finished basement family room, not an unfinished crawl space you never enter. If you have an existing mitigation system, check the manometer twice a year and confirm the fan is running; fans are mechanical and they do eventually fail.
If you are planning to sell in the next year, testing early is strictly to your advantage. A high result found now is a scheduled $1,200 project on your terms. The same result found during a buyer's inspection period is a negotiation you are running on a 3-business-day clock.
Seven in ten Central Iowa homes will test above the action level. The law makes your seller disclose what they know and hand you a fact sheet, but it does not make anyone test. Testing costs a fraction of your inspection budget, mitigation is a four-figure permanent fix, and both fit comfortably inside a normal Iowa purchase agreement timeline if you schedule the test on the first day of your inspection period.
If you are buying in Ankeny, Ames, Johnston, Bondurant, Waukee, or anywhere in the corridor between them, build radon into your inspection plan from the start rather than treating it as an add-on. I walk every buyer client through this before we write an offer, along with the rest of the inspection strategy for the specific house and the specific seller. If you want that conversation - no pressure, no obligation - reach out and we will go through it together.
This article is educational and is not legal, medical, or tax advice. Radon measurement and mitigation should be performed by an Iowa-credentialed specialist. For health guidance, consult Iowa HHS radon resources or your physician; for contract questions, consult a real estate attorney.
Jackson Krile | Flanders Team | RE/MAX Real Estate Center
515.490.8614 · Jackson@FlandersTeam.com
Let's talk through your specific situation - no pressure.