Why Our Free Radon Test Kits Come With a Refundable Deposit

We're putting together a free radon test-kit program for Colorado homeowners — with one twist that surprises people: a $20 deposit you get back in full the moment your kit reaches the lab. Not a charge. A deposit. Here's the slightly uncomfortable reason it exists.

Most free radon test kits are never used

Hand out free radon kits and a large share simply never come back. It's one of the better-documented facts in public-health testing:

• A peer-reviewed evaluation of Pennsylvania's free radon-kit program tracked 24,165 kits distributed from 2002–2023. The overall return rate was 47.7% — and in some years dipped as low as 30%.
• A randomized controlled trial in the UK mailing free, unsolicited radon kits saw just 21.9% returned. Even the best behaviorally-optimized version of the mailing only reached 32.6%.

Read that again: in a well-run, gold-standard program, fewer than half the free kits came back. The most common fate of a free radon kit isn't a test result — it's a kitchen drawer.

That matters, because a kit that never gets used protects no one. The goal was never to give away kits. The goal is to get homes tested.

"Free" has a follow-through problem

This isn't about people being lazy. It's about how "free" works in our heads. When something costs you nothing, skipping it also costs you nothing — there's no commitment, no small voice reminding you it's sitting in the drawer. Behavioral economists call the flip side loss aversion: we work harder to avoid losing something we've already put up than to gain the same thing for free.

A tiny amount of your own money on the line flips the kit from "free thing I'll get to eventually" into "thing I've already committed to."

The honest part: nobody has proven the exact fix

We went looking for a clean study showing free-versus-paid radon-kit return rates head to head. It doesn't exist. There's no published, peer-reviewed trial that pins down exactly how much a deposit lifts radon-kit returns.

So we're not going to quote you a magic number. What we do have is decades of behavioral-economics research on loss aversion and commitment devices, plus the consistent practical observation of the lab operators who run these programs at scale. They all point the same direction: a small amount of skin in the game gets more kits used and returned. We're making a reasoned bet — and we'll measure the real number as kits go out.

How the deposit actually works

• $20, fully refundable. You get every cent back the moment your kit arrives at the lab. Done correctly, the test costs you nothing.
• It's a commitment device, not a cost. The deposit's only job is to make the kit more likely to get used. Think of it like the hold a store puts on your card — money that comes right back once you follow through.
• It keeps the program honest. Deposits from the handful of kits that never come back help cover the cost of the kits that do — which is what lets us keep offering them.

Why this matters in Colorado

Colorado has some of the highest indoor radon in the country. Across 214,362 pre-mitigation tests in the CDPHE 2005–2024 dataset, 46.9% came back at or above the EPA action level of 4 pCi/L — you can see the county-by-county data here. Much of the state sits in EPA Radon Zone 1, the highest-potential designation.

"Radon is the leading cause of lung cancer among non-smokers." — U.S. EPA

But none of that data tells you about your home — radon follows geology and construction, and levels vary house to house, even on the same block. The only way to know your level is to test the actual house. A kit only helps if you run it and send it back. That's the entire point of the deposit.

Get on the list

Free kits roll out to Denver-metro and Front-Range homeowners first (the area our partner mitigation team covers). Join the waitlist → and we'll email you the day they're ready.

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Sources

• Pennsylvania free radon-kit program evaluation, 2002–2023 (24,165 kits, 47.7% return): PMC12205789
• Randomized trial of radon test-kit uptake (unsolicited free kits 21.9%; behaviorally-informed letter 32.6%): PMC10663451
• Colorado radon test results, 2005–2024: CDPHE dataset