Question 1

What is radon?

Accepted Answer

Radon is a naturally occurring radioactive gas that comes from the breakdown of uranium in soil, rock, and water. It is colorless, odorless, and tasteless, and can enter homes through cracks in the foundation, gaps around pipes, and other openings. Missouri DHSS reports that radon is present in every Missouri county.

Question 2

What should I do at 4.0 pCi/L?

Accepted Answer

If a confirmed test result is at or above 4.0 pCi/L, the EPA and Missouri DHSS recommend taking action to reduce radon in your home. This typically means installing a radon mitigation system. There is no truly safe level of radon—the EPA also suggests considering action between 2.0 and 4.0 pCi/L.

Question 3

How much does mitigation cost?

Accepted Answer

Missouri DHSS reports that mitigation commonly ranges from approximately $500 to $2,500, depending on the home's size and construction. Factors include foundation type, number of suction points, crawl-space work, pipe routing, and electrical requirements.

Question 4

Does mitigation work in basements?

Accepted Answer

Yes. Basement homes are commonly mitigated using sub-slab depressurization, where a pipe is installed through the basement floor slab and radon is drawn from beneath the foundation. The same approach works for crawl spaces (with a vapor barrier) and slab-on-grade homes.

Question 5

Who pays for mitigation during a home sale?

Accepted Answer

There is no legal requirement. Radon mitigation is a negotiation point between buyer and seller. Common approaches include the seller installing the system, providing a credit at closing, or the buyer handling it after closing.

Question 6

What certification should a provider hold?

Accepted Answer

Missouri recommends checking that your radon professional holds certification from either the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). You can verify certification through the NRPP or NRSB websites.

Question 7

Can Missouri residents get a free test kit?

Accepted Answer

Yes. Missouri residents may request one free short-term radon test kit per household while supplies last through the Missouri DHSS. Columbia Radon Guide does not distribute kits—requests are fulfilled directly by the state.

Question 8

Can you see or smell radon?

Accepted Answer

No. Radon is completely invisible—it has no color, odor, or taste. The only way to know whether your home has elevated radon is to test.

Question 9

What does pCi/L mean?

Accepted Answer

pCi/L stands for picocuries per liter, the unit used to measure radon concentration in air. The EPA action level is 4.0 pCi/L, meaning mitigation is recommended when a confirmed result is at or above that level.

Question 10

Should I retest first?

Accepted Answer

If your result was from a short-term test and was close to 4.0 pCi/L, or if the test conditions were not ideal, a follow-up test can help confirm the result. If the result was significantly above 4.0 pCi/L (for example, above 8.0), Missouri DHSS recommends taking action rather than retesting.

Question 11

How long does installation take?

Accepted Answer

Most radon mitigation systems can be installed in a single day, typically taking 4–8 hours. Homes with crawl spaces or complex foundations may take longer.

Question 12

Will the fan be noisy?

Accepted Answer

Radon fans are designed to run continuously and are generally quiet—similar to a low hum. They are typically mounted outside the living space, in an attic, or on the exterior, so noise inside the home is minimal.

Question 13

Where will the pipe be installed?

Accepted Answer

The pipe can be routed through the interior of the home (through closets or utility chases) or along the exterior wall. The best route depends on your home's layout and aesthetic preferences.

Question 14

Will the exterior pipe be visible?

Accepted Answer

If the pipe is routed along the exterior, it will be visible from outside. It is typically a 3-inch or 4-inch PVC pipe painted to match or left white. Interior routing keeps the exterior clean but may cost more.

Question 15

Does mitigation work with crawl spaces?

Accepted Answer

Yes. For crawl-space homes, a vapor barrier is installed over the soil and sealed to the foundation walls. A fan draws radon from beneath the barrier and vents it outside.

Question 16

What about slab-on-grade homes?

Accepted Answer

Yes. Slab-on-grade homes are mitigated by installing a suction point through the concrete slab, similar to basement systems. The pipe is then routed to the exterior.

Question 17

Should legal-transaction testing be professional?

Accepted Answer

Yes. Missouri recommends that testing for a real-estate transaction be performed by a professional using a continuous radon monitor, rather than a DIY kit, to ensure the test follows proper protocols and the result is accepted during negotiations.

Question 18

Is post-mitigation testing necessary?

Accepted Answer

Yes. A post-mitigation test should be conducted 24 hours to 30 days after installation to confirm the system has reduced radon below the action level. Missouri DHSS also recommends retesting every two years.

Question 19

How much electricity does a fan use?

Accepted Answer

Radon fans typically use a small amount of electricity—roughly equivalent to a single light bulb, often between 30 and 100 watts depending on the fan model. The annual cost is usually modest.

Question 20

How long does a radon fan last?

Accepted Answer

Radon fans typically last 5 to 10 years, though some last longer. When a fan fails, the manometer will show equal liquid levels, indicating the system is no longer pulling a vacuum. Fan replacement is a common repair.

Question 21

How can I tell whether an existing system works?

Accepted Answer

Check the manometer—the U-tube pressure gauge on the pipe. If the liquid levels are unequal, the fan is running and the system is pulling a vacuum. If the levels are equal, the fan may not be running. You can also conduct a short-term radon test to confirm the system is reducing radon effectively.

Question 22

Can an old system be repaired?

Accepted Answer

Yes. Common repairs include replacing the fan, resealing cracks or the sump pit, adjusting the pipe routing, or adding a second suction point. A qualified professional can diagnose the issue and recommend a repair.

Question 23

What should a written estimate contain?

Accepted Answer

A written estimate should include the system type, location of the pipe and fan, number of suction points, any crawl-space or sump work, electrical requirements, post-mitigation testing, warranty terms, and the total price. Always ask for details in writing before proceeding.

Radon Questions Answered

The questions that matter most

What is radon?

What should I do at 4.0 pCi/L?

How much does mitigation cost?

Does mitigation work in basements?

Who pays for mitigation during a home sale?

What certification should a provider hold?

Can Missouri residents get a free test kit?

Additional radon questions

Understanding radon

Your test result

Cost and installation

Foundation types

Home sales

After installation

Existing systems

Estimates

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