Radon Testing in Central Illinois: Why It Matters and What the Numbers Mean

Most of Illinois sits in EPA Radon Zone 1 — the highest-risk zone in the country for residential radon exposure. According to the Illinois Emergency Management Agency, about 4 out of every 10 homes tested in Illinois have radon levels at or above the EPA action level.

If you’re buying a home in Central Illinois — or you’ve never tested the home you live in — this matters. Here’s what you should know.

What is radon?

Radon is a naturally occurring radioactive gas that seeps up out of the soil. It’s colorless, odorless, and you can’t taste it. It enters homes through cracks in foundations, floor-to-wall joints, sump pits, and any other opening between the soil and the basement or crawl space.

Once inside, radon decays into solid radioactive particles that get inhaled into the lungs. Over years of exposure, those particles cause lung cancer.

The EPA estimates radon causes about 21,000 lung cancer deaths per year in the United States — making it the second-leading cause of lung cancer after smoking, and the leading cause among non-smokers.

How testing works

We use a continuous radon monitor — a calibrated digital device that samples the air every hour for 48 hours. This is more accurate and more reliable than the charcoal canisters you can buy at the hardware store, and the results can’t be tampered with mid-test.

The test runs under “closed-house” conditions:

• Windows shut for 12 hours before the test starts
• Windows stay shut during the 48 hours
• HVAC operates normally
• No one tampers with the monitor

After 48 hours, we retrieve the device and email a report with the average level in picocuries per liter (pCi/L).

What the numbers mean

Level	What it means
Below 2.0 pCi/L	Low — no action needed
2.0 to 3.9 pCi/L	Moderate — consider mitigation
4.0 pCi/L or higher	EPA action level — mitigation strongly recommended

The EPA action level is 4.0 pCi/L for a reason: there’s no truly “safe” level of radon, but at 4.0 the lifetime risk of lung cancer becomes high enough that mitigation is clearly worth doing.

Even levels of 2.0 to 3.9 pCi/L are worth addressing if you can. The World Health Organization recommends action at 2.7 pCi/L.

What mitigation costs

A radon mitigation system is a fan that pulls air out from under the foundation slab and vents it above the roofline. Installed cost in Central Illinois is typically $1,200 to $2,500. Once installed, it reduces radon levels dramatically — usually to under 2.0 pCi/L.

Mitigation contractors are licensed separately. We don’t sell mitigation — that’s part of how we keep the test honest.

When to test

• Always when buying a home. Negotiate based on the result.
• Every 2 years if you live in a home you’ve never tested.
• After major renovations that could change air circulation.
• After installing a mitigation system (post-mitigation test confirms it’s working).

Bottom line

Radon is a real, measurable risk in Central Illinois. The test costs $125 to $175. If your house has a problem, you’ll want to know. If it doesn’t, you’ll have peace of mind.

Schedule a radon test — standalone or with an inspection.