Radon Testing & Mitigation in O’Fallon, MO

In O’Fallon, MO, Air Sense Environmental tests homes for radon, installs radon mitigation systems, tests indoor air quality and encapsulates crawl spaces. Every radon job in St. Charles County is measured against the EPA action level of 4.0 pCi/L, and the team is NRPP-certified and IEMA-licensed (#RNM20232346).

Is radon a problem in O’Fallon, MO?

Yes. St. Charles County is in EPA Radon Zone 2, where the predicted average indoor radon level is 2 to 4 pCi/L, and individual O’Fallon 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. O’Fallon is the largest suburb of St. Louis, with more than 90,000 residents, and most of its housing went up between the 1990s and 2010s on poured basements set into St. Charles County’s silty clay soils.

A O’Fallon neighbor’s reading is a signal, not an answer. The soil under one lot, the cracks in one slab and the way one sump pit was sealed decide the number, which is why two similar homes a few doors apart can land on opposite sides of the action level.

Radon testing in O’Fallon, MO

A O’Fallon radon test runs 48 hours under closed-house conditions on a calibrated continuous monitor, and the report shows the hourly data as well as the average. Radon testing in O’Fallon covers how the test works, and the radon testing cost guide holds current pricing.

Radon mitigation in O’Fallon, MO

When a O’Fallon home tests at or above 4.0 pCi/L, the same team designs and installs the radon mitigation system, usually in a single day, and retests to confirm the home is below the action level. See radon mitigation in O’Fallon for the process, documented results and warranty.

Indoor air quality testing in O’Fallon, MO

An indoor air quality assessment for a O’Fallon home logs particulate matter, chemical vapors, CO2, CO and humidity at one-minute intervals for 48 hours or more, so the fix is based on data. Details are on indoor air quality in O’Fallon.

Crawl space encapsulation in O’Fallon, MO

For O’Fallon homes with a crawl space, encapsulation lays a sealed vapor barrier over the soil and walls and adds humidity control, keeping damp air and soil gas out of the rooms above. Read more on the St. Louis crawl space encapsulation page.

Which O’Fallon homes does Air Sense Environmental work on?

The O’Fallon homes the team sees most often:

• 1990s and 2000s subdivision homes on poured basements along Highway K and Highway N
• Homes in the older core near Main Street and the original town
• Walkout-basement homes on the sloped lots toward Dardenne Prairie
• Newer slab-on-grade villas and townhomes near Interstate 64

What should O’Fallon homeowners expect?

1. Test first. A 48-hour continuous monitor test gives the number everything else depends on.
2. Read the report together. You get the hourly data and a plain explanation of what it means for the house.
3. Design the fix. If the reading is at or above 4.0 pCi/L, the system is designed around your foundation during a free in-home estimate.
4. Install and verify. Most systems go in within a single day, and a post-mitigation test confirms the result.

About O’Fallon, MO

O’Fallon ( oh-FAL-ən) is a city in St. Charles County, Missouri, United States. It is part of the St. Louis metropolitan statistical area, located along Interstates 64 and 70 between Lake St. Louis and St. Peters. As of the 2020 census, O’Fallon had a population of 91,316, making it the most populous suburb of St. Louis, as well as the most populous municipality in St. Charles County and the 7th most populous in Missouri. O’Fallon’s namesake in St.

O’Fallon neighborhoods and nearby communities

Air Sense Environmental works across O’Fallon, MO, including the Highway K corridor, the original town along Main Street and the neighborhoods toward Dardenne Prairie, in ZIP codes 63366 and 63368. Nearby communities with their own service pages:

• Radon testing and mitigation in St. Peters, MO
• Radon testing and mitigation in St. Charles, MO
• Radon testing and mitigation in Wentzville, MO
• All Air Sense Environmental service areas

From Our Work