Radon Testing in St. Louis, MO

Accurate Radon Testing for Your Home's Safety

Radon is a naturally occurring radioactive gas you cannot see, smell, or taste, and the only way to know your home’s level is to test. Air Sense Environmental provides certified 48-hour radon testing for homeowners and real estate transactions across St. Louis, MO, St. Louis County, St. Charles County, and the Illinois Metro East. Our IEMA-licensed team (#RNM20232346) uses professional continuous radon monitors, not mail-away kits, so you get lab-grade accuracy with a same-day report when the test ends.

The St. Louis region sits largely in EPA Radon Zones 1 and 2, the two highest-potential categories. The EPA action level is 4.0 pCi/L: at or above that number, mitigation is recommended. Roughly one in three homes we test in this area comes back elevated, and identical houses next door to each other can test completely differently. Testing is the only way to know.

How Professional Radon Testing Works

Monitor placement. We place a calibrated continuous radon monitor in the lowest lived-in level of your home, following EPA closed-house protocol.
48 hours of measurement. The monitor records radon concentration every hour, along with temperature, humidity, and pressure, capturing how your level swings day and night. Radon can fluctuate two to three times within a single day, which single-moment tests miss.
Same-day report. When the test ends, you get a clear written report showing your hourly readings, your average, and exactly where it falls against the EPA action level of 4.0 pCi/L, with a plain-language recommendation on what to do next.

Why Continuous Monitors Beat Basic Test Kits

Why Test For Radon?

The EPA recommends every home be tested, and re-tested every two years, because radon levels change as houses settle, soil shifts, and seasons turn. Test again sooner any time you finish a basement, change your HVAC system, or complete a major renovation. Homes with an active radon mitigation system should also re-test every two years to verify the system is still performing.

Buying or selling? Radon testing is now standard in St. Louis-area transactions, and an elevated result does not have to kill a deal: mitigation is a routine, affordable fix that we can quote from the test report, often within the inspection window. Wondering which you need first, testing or mitigation? For buyers and sellers, see our guide to radon in St. Louis real estate.

What Happens After the Test

If your result is under 4.0 pCi/L, you are done, and we will tell you exactly when to re-test. If it is at or above the EPA action level, we walk you through your mitigation options, give you a written quote, and, if you go ahead, verify the finished system with a post-mitigation test. Testing and mitigation under one licensed roof means no handoffs, no second contractor, and no upsell pressure: about two thirds of the homes we test need no mitigation at all.

Radon Testing FAQs

How much does a radon test cost in St. Louis?

Call 314-664-9807 for current pricing and scheduling, or see our radon testing cost guide for typical ranges.

How long does the test take?

48 hours minimum under EPA protocol, with your report delivered the same day the test ends.

Are DIY kits good enough?

They can screen, but they are slower (lab mail-in), give one blended average, and have no tamper protection, which is why lenders and relocation companies typically require professional continuous-monitor results.

What reading is dangerous?

The EPA action level is 4.0 pCi/L. The EPA also suggests considering mitigation between 2.0 and 4.0 pCi/L. No level of radon is considered completely risk-free, so lower is always better.

Where Do We Test For Radon?

Map of Edwardsville, IL

Illinois

Alton, Belleville, Bethalto, Collinsville, Edwardsville, Glen Carbon, Godfrey, Granite City, Highland, Maryville, Troy, Fairview Heights, O’Fallon, Swansea, Brighton, Elsah, Jerseyville, Moro, Gillespie, and Staunton.

Air Sense Environmental services are instrumental in ensuring proper testing and effective mitigation within these communities.

Map of St. Louis, MO

Missouri

St. Louis County and St. Charles County, Missouri, cities such as Chesterfield, Florissant, Kirkwood, Maryland Heights, St. Peters, O’Fallon, St. Charles, Wentzville and surrounding area.

Air Sense Environmental plays a vital role in ensuring these communities undergo proper testing and effective radon mitigation.