Johnston City, IL Radon Levels

Q: What EPA Radon Zone is Johnston City in?

Johnston City is in Williamson County, EPA Zone 2.

Q: How much does radon mitigation cost in Johnston City?

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

Check local Johnston City radon levels and find certified testing and mitigation professionals to keep your home safe

Johnston City, IL Radon Facts

EPA Radon Zone Zone 2 — Moderate Risk 2–4 pCi/L (Zone 2)

County Williamson County, IL

Zip Code 62951

Situated in southern Illinois within Williamson County, Johnston City sits on Pennsylvanian-era coal measures and shale deposits typical of the Illinois Basin region. With testing data limited for this 62951 zip code area, homeowners should consider individual testing to establish their specific radon exposure levels.

5.00

pCi/L area average

Above EPA Action Level

Williamson County average: 5.00 pCi/L, based on 1 user-submitted test across 1 city in the county. No homeowner readings have been submitted for Johnston City itself yet, so this county figure is the closest available benchmark. The EPA recommends taking action at or above 4.0 pCi/L.

4.0 EPA

10+

Johnston City, IL Radon Mitigation

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

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Radon Readings Near Johnston City, IL

No homeowner tests have been submitted for Johnston City yet. The closest cities with user-submitted radon data are shown below — explore them to gauge local conditions. Radon varies by home, so testing is the only way to know your level.

City	Distance	Avg User Level	Readings
Marion	6.8 mi	5.00 pCi/L	1
Murphysboro	22.8 mi	10.00 pCi/L	1
Mount Vernon	34.0 mi	4.00 pCi/L	1
Campbell Hill	36.6 mi	1.00 pCi/L	1
Kell	47.7 mi	5.00 pCi/L	1

Williamson County Radon Profile

EPA mapping assigns Williamson County to Radon Zone 2, indicating moderate predicted indoor screening levels in the 2 to 4 pCi/L range based on regional geology. Homeowner-submitted tests from 1 city in Williamson County average 5.00 pCi/L across 1 test — above the EPA's 4 pCi/L action level, reinforcing the need for testing across the county. As the second leading cause of lung cancer in the U.S., radon warrants testing in every Williamson County home regardless of zone or a neighbor's results.

Radon FAQ for Johnston City, IL

What EPA Radon Zone is Johnston City in?

Johnston City and the 62951 zip code are in Williamson County, which has an EPA assigned Radon Zone of 2. A zone of 2 predicts an average indoor radon screening level between 2 and 4 pCi/L.

Why are radon readings shown from areas near Johnston City?

No homeowner radon tests have been submitted for Johnston City yet. Because radon is driven by regional soil and bedrock geology, readings from the closest cities—and the Williamson County average—are the best available indicator of local conditions until Johnston City homeowners submit their own results. The EPA still recommends testing every individual home, since levels can vary significantly from house to house.

How much does radon mitigation cost in Johnston City?

Radon mitigation in Johnston City 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 Johnston City?

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.