O Fallon, MO Radon Mitigation and Testing

Q: What is the average radon level in O Fallon, MO?

Based on 4 user-submitted tests, the average radon level is 7.80 pCi/L.

Q: What EPA Radon Zone is O Fallon in?

O Fallon is in St Charles County, EPA Zone Unknown.

Q: How much does radon mitigation cost in O Fallon?

Radon mitigation typically costs between $800 and $2,000. Most standard systems fall in the $1,000-$1,500 range.

Avg: 7.80 pCi/L

St Charles County

EPA Zone Unknown

4 user tests

O'Fallon residents in St. Charles County face significantly elevated radon levels, with local testing showing an average of 8.67 pCi/L across zip codes 63366 and 63368. These readings substantially exceed EPA action thresholds, likely reflecting the area's limestone bedrock and glacial deposits common throughout the St. Louis Metro region. Given these elevated levels and the community's suburban housing stock with full basements, professional radon mitigation is strongly recommended for affected properties.

7.80

pCi/L average

Above EPA Action Level

Based on 4 user-submitted radon tests for homes in O Fallon, MO. The EPA recommends taking action at or above 4.0 pCi/L.

4.0 EPA

10+

O Fallon, MO Radon Mitigation

Professional radon mitigation is the most effective way to permanently lower radon levels and protect your household.

O Fallon, MO Radon Testing

Finding qualified radon testing professionals is the first step toward protecting your home.

O Fallon, Missouri Radon Levels

User-submitted radon test readings from homes in the O Fallon area.

Radon Level	City	Home Age	Foundation	Submitted
14 pCi/L	O Fallon, MO	21-50 Years	Full Basement	Sep 2024
5 pCi/L	O Fallon, MO	0-20 Years	Full Basement	Dec 2023
7 pCi/L	O Fallon, MO	0-20 Years	Full Basement	Sep 2022

Have a radon test result for O Fallon? Submit your reading to help other homeowners.

O Fallon Radon Facts

Key details about the radon risk profile for O Fallon and the 63366 zip code area.

EPA Radon Zone

Unknown

County

St Charles County, MO

Zip Code

63366

Predicted Screening Level

Unknown

Avg. User Submitted Level

7.80 pCi/L

User Tests Submitted

O Fallon and the 63366 zip code are located in St Charles County, which has an EPA assigned Radon Zone of Unknown. A radon zone of Unknown does not have sufficient data for classification. The EPA recommends testing every home regardless of zone classification.

Radon FAQ for O Fallon, MO

What is the average radon level in O Fallon, MO?

Based on 4 user-submitted tests, the average radon level in O Fallon is 7.80 pCi/L. This exceeds the EPA's recommended action level of 4.0 pCi/L, and radon testing is recommended for all homes in the area.

What EPA Radon Zone is O Fallon in?

O Fallon and the 63366 zip code are in St Charles County, which has an EPA assigned Radon Zone of Unknown. A zone of Unknown does not have sufficient data for classification.

How much does radon mitigation cost in O Fallon?

Radon mitigation in O Fallon typically costs between $800 and $2,000. Most homes with standard basements can be mitigated with a sub-slab depressurization system in the $1,000–$1,500 range. Factors that can increase cost include complex foundations, crawl spaces, or very high radon levels.

Should I test for radon if I'm buying a home in O Fallon?

Yes. Radon testing should be part of every home purchase. A short-term radon test is typically included as part of the home inspection process and costs $150–$250. If elevated levels are found, you can negotiate mitigation as part of the sale.

Most Active Radon Markets in Missouri

Cities with the most user-submitted radon test data in the state.

City	Avg User Radon Level	Submissions
Troy	8.50 pCi/L	4
Lees Summit	7.00 pCi/L	3
Columbia	3.00 pCi/L	2
House Springs	7.00 pCi/L	1
Kansas City	7.00 pCi/L	1
Springfield	7.00 pCi/L	1
Independence	5.00 pCi/L	1
Wentzville	No submissions	0