Radon Testing in Chesterfield, MO

Radon testing in Chesterfield, MO measures how much radon gas has built up inside a home, reported in picocuries per liter (pCi/L) against the EPA action level of 4.0 pCi/L. Air Sense Environmental places a calibrated continuous radon monitor in Chesterfield homes for a 48-hour closed-house test and delivers a documented report, so buyers, sellers and homeowners in St. Louis County know whether the house sits above the action level. Every Chesterfield radon question comes back to one measurement. Air Sense Environmental gets that measurement with a calibrated monitor, not a mail-in kit.

Is radon a problem in Chesterfield, MO?

Yes. St. Louis County is in EPA Radon Zone 2, where the predicted average indoor radon level is 2 to 4 pCi/L, and individual Chesterfield homes routinely test well above the 4.0 pCi/L action level. Missouri’s Department of Health and Senior Services reports that roughly one in three homes tested through its statewide program between 2003 and 2023 came back at or above 4.0 pCi/L. Chesterfield splits into two very different foundations: the Chesterfield Valley, the Missouri River floodplain once called Gumbo Flats, with deep silty soil, and the hills above it where 1970s to 1990s subdivisions sit on clay over bedrock.

Because radon depends on the ground under a single lot and the openings in a single foundation, Chesterfield results change from address to address. Testing the specific house is the only way to know where it stands.

Which Chesterfield homes should be tested for radon?

The EPA’s advice applies to all of Chesterfield: test every home, retest after major work on the foundation or HVAC, and retest every two years with a mitigation system in place. Air Sense Environmental sees these Chesterfield, MO home types most often:

• Two-story and walkout-basement homes in the subdivisions off Clarkson Road and Olive Boulevard
• Homes in the older parts of Chesterfield built before the city incorporated in 1988
• Slab-on-grade and newer homes in and around the Chesterfield Valley
• Homes with finished basements used as bedrooms or offices, where the lowest occupied level is where people spend their time
• Any home being bought or sold, where a radon test during the inspection period protects both sides of the deal

How does a radon test work in a Chesterfield home?

1. Monitor placement. A calibrated continuous radon monitor goes on the lowest level of the home that is or could be lived in, away from drafts, windows and exterior doors, following EPA and NRPP placement protocol. In a Chesterfield split-level, the lowest finished level is the right spot even when the family rarely uses it.
2. 48 hours of closed-house conditions. Windows stay closed and the HVAC runs normally while the monitor records hourly readings, with tamper detection so the result stands up in a real estate transaction.
3. A documented report. You receive the hourly data and the average reading against the 4.0 pCi/L action level, with a plain explanation of what the number means for your Chesterfield home.

How much does radon testing cost in Chesterfield, MO?

Chesterfield homeowners ask about price first, so Air Sense Environmental keeps its pricing in one place: the St. Louis radon testing cost guide. The main radon testing page explains when a professional continuous monitor is worth it over a DIY kit. Call 314-664-9807 with your Chesterfield address for an exact quote.

What happens if a Chesterfield radon test comes back at or above 4.0 pCi/L?

When a Chesterfield home tests at or above 4.0 pCi/L, Air Sense Environmental designs the sub-slab depressurization system, installs it and retests. Start with radon mitigation in Chesterfield, MO, read the full process on the St. Louis radon mitigation services page, and expect a post-mitigation test to confirm the home is below the action level.

Radon testing near Chesterfield: neighborhoods and nearby communities

Air Sense Environmental tests homes across Chesterfield, MO, including Chesterfield Valley, the Clarkson Road corridor and the neighborhoods above Faust Park, in ZIP codes 63005 and 63017. Nearby communities with their own service pages:

• Radon testing and mitigation in Ballwin, MO
• Radon testing and mitigation in Maryland Heights, MO
• Radon testing and mitigation in Wildwood, MO
• Radon testing and mitigation in Creve Coeur, MO
• All Air Sense Environmental service areas

Related from Air Sense Environmental: Indoor Air Quality Testing and Reviews & Projects.

From Our Work