Radon Testing in Florissant, MO

Radon testing in Florissant, 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 Florissant 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 Florissant 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 Florissant, 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 Florissant 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. Florissant in north St. Louis County was built out mostly between the 1950s and 1970s, so its ranch and split-level homes sit on block or poured basements that are now 50 to 70 years old, with cracks and floor drains that radon uses to enter.

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

Which Florissant homes should be tested for radon?

The EPA’s advice applies to all of Florissant: 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 Florissant, MO home types most often:

• 1950s and 1960s ranch homes with block basements throughout the city
• Split-level homes from the 1960s and 1970s, where the lower level is often a family room or bedroom
• Homes in Old Town Florissant with older foundations and cellars
• Homes with sump pits or floor drains, which are common radon entry points in north county
• 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 Florissant 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 Florissant 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 Florissant home.

How much does radon testing cost in Florissant, MO?

Florissant 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 Florissant address for an exact quote.

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

When a Florissant 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 Florissant, 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 Florissant: neighborhoods and nearby communities

Air Sense Environmental tests homes across Florissant, MO, including Old Town Florissant, the New Halls Ferry Road corridor and the neighborhoods toward Spanish Lake, in ZIP codes 63031, 63033 and 63034. Nearby communities with their own service pages:

• Radon testing and mitigation in Hazelwood, MO
• Radon testing and mitigation in St. Louis, MO
• Radon testing and mitigation in Maryland Heights, MO
• Radon testing and mitigation in St. Charles, MO
• All Air Sense Environmental service areas

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

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