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Radon Mitigation in St. Louis, MO

IEMA-certified · NRPP-certified · BBB A-rated · 132+ five-star reviews · Free in-home estimate

What is radon mitigation?

Radon mitigation is the process of reducing radon gas concentrations inside a home or building to safe levels using sub-slab depressurization, ventilation systems, and sealing techniques. Air Sense Environmental is St. Louis's IEMA-certified (License #RNM20232346) and NRPP-certified radon mitigation specialist, serving homes and commercial properties across Missouri and Illinois from our Edwardsville, IL headquarters. Every mitigation project ends with a post-mitigation test verifying your radon levels have dropped to the EPA action level of 4.0 pCi/L or below. Most of our installations land well under 2.0 pCi/L.

If your radon test came back high, or you're a home buyer whose inspection just flagged elevated radon, you don't have to figure this out alone. Call 314-664-9807 for a free in-home estimate. We've installed 132+ systems across the St. Louis metro with five-star reviews on every one of them.

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Components of a radon mitigation system may include

Sub-Slab Depressurization (SSD) System

This is one of the most common types of radon mitigation systems. It involves installing pipes and a fan in the building's foundation to create a vacuum effect, drawing radon gas from the soil beneath the building and venting it safely outside, away from occupied areas.

Monitoring and Alarm Systems

Some advanced systems may include monitoring devices or alarms to provide ongoing information about radon levels or to alert occupants in case of system malfunction. Air Sense Environmental is a dealer for all Air Things Monitors. Check the bottom of your invoice for discounted pricing on long term radon monitors for your home and system.

Crawl Space or Basement Ventilation

For buildings with crawl spaces or basements, moisture barriers act as a deterrent to soil gases, including radon, by reducing their movement from the ground into the crawl space and subsequently into the home. Radon can migrate as a gas through porous materials, and a properly installed moisture barrier can help limit its entry.

Sealing and Caulking

Mitigation may also involve sealing cracks, gaps, or other openings in the foundation or floors to prevent radon entry.

Radon Exhaust Fans

Fans are used to create negative pressure within the system, ensuring that radon gas is effectively pulled from the soil and expelled outside, away from the building.

Sump-Pump Mitigation

In properties with sump pumps, Air Sense will repair/replace the current lid to provide an air tight seal from the sump pit to the open atmosphere inside the home.

How a Radon Mitigation Install Works, Start to Finish

  1. Free in-home assessment. We inspect your foundation type (basement, crawl space, or slab), review your test results, and identify the best suction point and exhaust route.

  2. Custom system design. Foundation type determines the method. Most St. Louis homes get sub-slab depressurization; crawl space homes get sub-membrane systems. See our guide to the types of radon mitigation systems to understand which fits your home.

  3. Installation. Most standard single-family installations are completed in a single visit. Read what to expect in our post on how long radon mitigation takes.

  4. Verification testing. Every job ends with a post-mitigation radon test. We do not consider the project complete until your level is confirmed below the EPA action level of 4.0 pCi/L, and most of our systems land under 2.0 pCi/L.

Older home? Stone foundations, dirt-floor basements, and additions each need their own approach. See radon mitigation in older St. Louis homes.

What Does Radon Mitigation Cost in St. Louis?

Radon mitigation system installation in St. Louis typically runs $650 to $1,200, depending on foundation type, home size, and how high your starting level is. That price includes the post-mitigation verification test. Air Sense Environmental provides free written estimates, and our full St. Louis radon mitigation cost guide breaks down every factor, including what makes a system cost more or less. Not sure whether you need mitigation at all? Start with testing first: our testing vs. mitigation guide explains the order of operations.

Key Benefits of a Professional Radon Mitigation System

Once high radon levels are confirmed in your home, the most important next step is to take action. A professionally installed radon mitigation system is the only reliable way to significantly reduce radon concentrations, providing a permanent solution for a healthier indoor environment.

Protect Your Family’s Health:

This is the most critical benefit. Radon is the second leading cause of lung cancer in the United States according to the EPA, and a mitigation system reduces radon levels to a safe concentration, significantly lowering the health risks for you and your loved ones.

Increase Your Home’s Value:

A home with a radon mitigation system is a major selling point. It shows potential buyers that the home is safe and has been responsibly maintained, which can be a significant advantage in a real estate transaction.

Enjoy Total Peace of Mind:

Stop worrying about the invisible threat of radon. A properly functioning mitigation system works 24/7 to protect your home, giving you the confidence that your family is breathing safer, cleaner air.

Improve Overall Indoor Air Quality:

In addition to venting radon, the system can also help reduce moisture levels and other soil gases from entering your home, which contributes to a less humid and healthier environment.

Investing in a radon mitigation system is a direct investment in your family’s long-term health and your property’s value. Contact Air Sense Environmental today to discuss your custom solution and schedule a free estimate.

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Verified Results on Every Installation

A mitigation system only counts if it works, and the proof is in the numbers. Every Air Sense Environmental installation ends with a post-mitigation test confirming your radon level dropped below the EPA action level of 4.0 pCi/L. Most of our systems bring homes under 2.0 pCi/L. If a post-mitigation reading ever comes back high, we adjust the system at no charge until it passes: a bigger fan, a second suction point, or additional sealing, whatever the house needs. That guarantee is why home inspectors and real estate agents across the metro refer their clients to us, and why we hold a BBB A rating with 132+ five-star reviews.

After installation, re-test every two years to confirm ongoing performance, and see our system maintenance guide for what to watch between tests. Still weighing it? Here is the data on whether radon mitigation really works.

Where Do We Perform Radon Mitigation?

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. 

Related from Air Sense Environmental: Radon Testing, Reviews & Projects, and FAQ.

Frequently Asked Questions About Radon Mitigation in St. Louis

How much does radon mitigation cost in St. Louis?

Most residential systems range from $1,200 to $2,500, depending on home size, foundation type, and complexity. Air Sense Environmental provides free in-home estimates with transparent pricing. For a deeper breakdown, see our 2026 St. Louis radon mitigation cost guide.

How long does a radon mitigation system installation take?

Most residential installations complete in 4 to 6 hours. Larger or more complex homes can take a full day. Commercial projects vary by building size and are quoted during the site visit.

What type of radon mitigation system do you install?

We design and install the full range. sub-slab depressurization, crawl space ventilation, sub-membrane depressurization, sump-pump mitigation, and sealing/caulking. The system type depends on your foundation and the radon entry points in your home.

Do I need a radon test before mitigation?

Yes. a recent radon test (within the last 12 months) confirms mitigation is needed and informs the system design. If you don’t have one, we run a 48-hour diagnostic test as the first step of the project.

Does radon mitigation really work?

Yes. A properly designed and installed system reduces radon to safe levels within 24-48 hours of activation. Air Sense Environmental verifies effectiveness with a post-mitigation test on every installation. if your levels aren’t safely below the EPA action level after install, we adjust and re-test at no additional cost.

What’s the difference between radon testing and radon mitigation?

Testing measures the radon level in your home (typically a 48-hour short-term test or a 90-day long-term test). Mitigation is the active solution. installing a system that reduces radon to safe levels. Most homes need testing first; if levels are at or above the EPA action level of 4.0 pCi/L, mitigation is recommended.

What happens if my radon levels are still high after mitigation?

We adjust the system and re-test at no additional cost. Air Sense Environmental’s post-mitigation guarantee means you don’t pay for a system that doesn’t work.

Will a radon mitigation system affect my home’s value?

A properly installed radon mitigation system is generally seen as a positive by home buyers and inspectors. documentation that the home has been tested, mitigated, and verified safe. Real estate transactions involving high-radon homes increasingly require mitigation before closing.

Are radon mitigation systems noisy?

A well-designed system runs at the noise level of a refrigerator. quiet enough that most homeowners forget it’s running. If you have an existing system that’s noticeably loud, the fan placement or duct routing may need adjustment.

What areas in the St. Louis metro does Air Sense serve?

The full Greater St. Louis metro. St. Louis City, St. Louis County, St. Charles County, Jefferson, Franklin, Madison, and St. Clair counties, plus all major cities in both Missouri and Illinois sides. See our service area page for the full list, or call 314-664-9807 to confirm coverage for your address.

Learn More About Radon Mitigation in St. Louis

Cities We Serve for Radon Mitigation

Air Sense Environmental provides radon mitigation across the greater St. Louis metro and Metro East. Find your area: