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*The Angi rating for Radon Detection And Reduction companies in Alton, MO is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Radon Detection And Reduction needs.

*The HomeAdvisor rating for Radon Detection And Reduction companies in Alton, MO is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Radon Detection And Reduction needs.

Last update on October 07, 2025

Top-Rated Radon detection and reduction specialists in Alton - Updated Nov 2026

Avatar for Ozark Radon Gone Corp.
Ozark Radon Gone Corp.
5.0(
24
)
Radon Gas - AbatementRadon Gas - Testing

Serving Alton, MO and surrounding areas

In business since 2021

Free estimates

"Brain is a professional at installing a radon mitigation fan! He was meticulous! Very thankful we hired him to help us. Radon is dropping!"
Response time7 hrs
Response rate86%
Recommended by70%of homeowners
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Avatar for SWAT Environmental, Inc.
SWAT Environmental, Inc.
4.5(
52
)
Radon Gas - Abatement

Serving Alton, MO and surrounding areas

In business since 1988

Free estimates

Credit card accepted

"I would definitely recommend this company to anyone!!! I hired them and the job was done nicely, Dan O'Brien was the technician who took care of the project and he did an excellent job, he answered all of my questions and explained to me everything related to Radon gas. When he finished setting everything up and the job was completed all the working area looked super clean and the installation looks just like it is part of the house and that has been there forever. This is what I call a Perfect and Complete execution of a Radon gas mitigation project."
Recommended by97%of homeowners
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HASS Consulting LLC
5.0(
4
)
Radon Gas - Testing

Serving Alton, MO and surrounding areas

In business since 2023

Free estimates

Credit card accepted

"I was extremely happy with the Quality Air Test that Mr Clark provided. It was reasonably priced and done effectively and efficiently… Results were received in a timely manner as he explained. He answered any questions I had and was professional and polite… I highly recommend HASS Consulting…"
Response time7 hrs
Recommended by75%of homeowners
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Radon Detection and Reduction FAQs, answered by experts

You'll need to test your home for radon after installing the mitigation system, then again every two years. If radon remains elevated, contact a licensed radon professional, either the contractor who installed the system or a different one, and have them evaluate the system. They may need to make some changes to improve its effectiveness and performance.

Radon enters your home when warm air begins to rise and exits through the roof, creating a vacuum that pulls cooler air from under the foundation. Part of that air is radon, which is an invisible, odorless gas that develops naturally when radioactive particles are deep within the ground. Those particles usually come from decaying matter in soil and rocks.

The cost to replace a radon fan ranges from $300 to $600 for the fan itself, with installation adding an additional $200 to $500. Overall, the total cost for replacement can range from $500 to $1,100, depending on factors such as the fan model, home size, and local labor rates. If the fan is part of a larger radon mitigation system, the price may be higher.

Keeping radon from getting into your home is much better than having to get rid of it once it's already indoors. While there may not be a way to fully prevent radon from getting into your home, there are things you can do to reduce the gas's ability to enter. 

Sealing foundation cracks and openings can help keep the gas from seeping inside. Improving air flow, such as by opening windows, can also be helpful. If you're building your home from scratch, talk to your contractor about using radon-resistant construction to keep the gas out.

The cost for a radon mitigation system typically ranges from $800 to $1,500, with an average around $1,000. The final price depends on several factors, including the size of your home, the severity of the radon issue, and the type of system required. Your home's foundation type also significantly impacts the cost. For example, sealing and ventilating an unfinished basement might cost around $4,600, while encapsulating a crawl space without a foundation slab can range from $1,500 to $15,000.

The Alton, MO homeowners’ guide to radon detection and reduction services

From average costs to expert advice, get all the answers you need to get your job done.

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