Ontario, WI Radon Levels

Q: What EPA Radon Zone is Ontario in?

Ontario is in Vernon County, EPA Zone 1.

Q: How much does radon mitigation cost in Ontario?

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

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

Ontario, WI Radon Facts

EPA Radon Zone Zone 1 — High Risk > 4.0 pCi/L (Zone 1)

County Vernon County, WI

Zip Code 54651

Ontario in Vernon County near the La Crosse Metro area has limited radon testing data available for residents. Wisconsin's driftless region features limestone bedrock that can contribute to elevated radon levels in homes with basements or lower-level living spaces. Testing is particularly important given the EPA Zone 1 designation for this area.

5.00

pCi/L area average

Above EPA Action Level

Vernon County average: 5.00 pCi/L, based on 2 user-submitted tests across 2 cities in the county. No homeowner readings have been submitted for Ontario 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+

Ontario, WI 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 Ontario, WI

No homeowner tests have been submitted for Ontario 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
Westby	13.2 mi	5.00 pCi/L	1
Kendall	13.6 mi	9.00 pCi/L	1
Viroqua	18.2 mi	5.00 pCi/L	1
Sparta	19.0 mi	5.00 pCi/L	2
La Valle	26.6 mi	9.00 pCi/L	2
Onalaska	32.9 mi	3.00 pCi/L	1
Blue River	33.2 mi	6.00 pCi/L	1
Reedsburg	33.8 mi	5.00 pCi/L	1

Vernon County Radon Profile

Vernon County falls in EPA Radon Zone 1, meaning the local uranium-bearing geology is predicted to drive average indoor radon screening levels above the EPA's 4 pCi/L action threshold. Homeowner-submitted tests from 2 cities in Vernon County average 5.00 pCi/L across 2 tests — above the EPA's 4 pCi/L action level, reinforcing the need for testing across the county. Since radon is the second leading cause of lung cancer nationally, the EPA urges every household in Vernon County to test, as levels can differ between neighboring homes.

Radon FAQ for Ontario, WI

What EPA Radon Zone is Ontario in?

Ontario and the 54651 zip code are in Vernon County, which has an EPA assigned Radon Zone of 1. A zone of 1 predicts an average indoor radon screening level greater than 4 pCi/L.

Why are radon readings shown from areas near Ontario?

No homeowner radon tests have been submitted for Ontario yet. Because radon is driven by regional soil and bedrock geology, readings from the closest cities—and the Vernon County average—are the best available indicator of local conditions until Ontario 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 Ontario?

Radon mitigation in Ontario 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 Ontario?

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.