Listed for: Testing
Verified:Ohio state license
Call 4 Corners Home Inspection LLC at (740) 973-9463No website listed
Locations and reports
Radon in Westerville, Ohio
Westerville lies in 2 counties, in EPA Zone 1; 68.3% of it is in Franklin County, where 71.9% of 16,142 reported tests (2008 to 2017, laboratory totals) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so the only way to know your home's level is to test it.
Data checked By Radon411Methodology
Share at 4+ pCi/L
71.9%
19.6 pts above OH
- Franklin
- 71.9%
- Ohio
- 52.3%
Franklin, 6th of 79 in OH, 2008 to 2017
Median result
6.8pCi/L
Action level reached
- Franklin
- 6.8 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Franklin's tests, 2008 to 2017
Highest county
72.2%
Delaware
- Delaware
- 72.2%
- Franklin
- 71.9%
2 counties, 2 with 30+ tests, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Franklin; Delaware Zone 1
Tests reported
16,142
In Franklin
- Franklin
- 16,142
- Delaware
- 3,730
Reported to CDC before any fix, 2008 to 2017
Read a result for Westerville
Starts at Franklin County's median, 6.8 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 6.8 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Franklin County's median reported result, 2008 to 2017.
The data
Westerville, What is published
What is published for Westerville
Information:
Every figure for Westerville is a county's
Radon data is published by county, not by city, and Westerville reaches into 2 counties: Franklin County and Delaware County. Each has its own EPA zone and its own CDC test figures, set side by side below and each labelled with its county. Only a test tells you about one home.
Westerville covers 12.6 square miles of land: 68.3% of it lies in Franklin County and 31.7% in Delaware County. About 38,165 people live there, 3,028 to the square mile.
Westerville, Counties
Westerville's counties, side by side
MeasuredEach county's own EPA zone and its own published CDC figures for 2008 to 2017, laboratory, the newest period any of them has. A county without a figure for that period is shown without one, never with a figure from another year.
- Franklin County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 71.9%
- Median result
- 6.8 pCi/L
- Tests reported
- 16,142 tests
- Annual years on file
- None
- Delaware County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 72.2%
- Median result
- 6.4 pCi/L
- Tests reported
- 3,730 tests
- Annual years on file
- None
| County | EPA zone | Reported tests at or above 4 pCi/L | Median reported result | Tests reported | Annual years on file |
|---|---|---|---|---|---|
| Franklin County | Zone 1: Highest predicted potential | 71.9% | 6.8 pCi/L | 16,142 tests | None |
| Delaware County | Zone 1: Highest predicted potential | 72.2% | 6.4 pCi/L | 3,730 tests | None |
Westerville spans 2 counties, each with its own EPA zone and its own CDC figure: Franklin County (Zone 1, 71.9% of 16,142 tests) and Delaware County (Zone 1, 72.2% of 3,730 tests).
Franklin County ranks 6th of 79 Ohio counties with 30 or more tests for that period, 19.6 points above the 52.3% pooled across Ohio's counties, 36.2 points above the national pool of 35.7%. Of the city's other county, Delaware County reported 72.2%.
Measured from the middle of Westerville, the nearest counties with a CDC figure for 2008 to 2017, laboratory are Licking County (23 miles, 71.2% of 4,694 tests), Union County (27 miles, 60.2% of 1,285 tests) and Morrow County (28 miles, 65.0% of 177 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 60.2% to 81.4%; the farthest of them, Marion County, is 34 miles away at 65.3%.
The directory lists 5 businesses with an address in Westerville, 4 for testing and 1 for mitigation. Ohio's other cities with a page of their own: Columbus, Dayton, Cincinnati and Toledo.
Against Ohio and its other counties
Shares of tests people chose to run and report, by county (2008 to 2017, laboratory); the state's is its counties' counts added up, calculated by Radon411. Only a test measures a home.
The counties around Westerville
By distance from the middle of Westerville; counties with 30 or more tests.
The median reported pre-mitigation result for 2008 to 2017, laboratory was 6.8 pCi/L in Franklin County and 6.4 pCi/L in Delaware County.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.
Westerville, Geology
The ground under Westerville
PredictedUSGS's geologic map puts all of Westerville's mapped land in one class: high radon potential. All of it lies in the area the map calls Till Plains, to which USGS gives a radon index of 14, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Till Plains | Glacial deposits underlain by Ordovician through Devonian limestone and shale. | High | 14 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Westerville beside its counties and Ohio
All of Westerville, like all of Franklin County, is rated high. Westerville has more high-potential ground than Ohio as a whole: 100% of its land against 62.8%.
The map rates the ground, not the air in any home.
Westerville, Homes
Homes in Westerville
Of Westerville's 15,878 homes, 68% are detached houses, against 53% across Franklin County; 16% are in buildings of five or more homes. Half of its homes were built before 1982, close to Franklin County's 1979: 12% date from before 1960 and 21% from 2000 or later. 74% of occupied homes are lived in by their owner (Franklin County: 53%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Westerville | Franklin County | Ohio |
|---|---|---|---|
| Housing units | 15,878 | 588,892 | 5,271,573 |
| Detached houses | 68% | 53% | 69% |
| In buildings of 5 or more | 16% | 25% | 15% |
| Mobile homes | under 1% | 1% | 4% |
| Built before 1960 | 12% | 26% | 38% |
| Built since 2000 | 21% | 22% | 16% |
| Middle year built | 1982 | 1979 | 1970 |
| Owner-occupied | 74% | 53% | 67% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.
Local help
Westerville, Professionals
Radon professionals listed in Westerville
Businesses whose listed city is Westerville, from the state registries and listings in the Radon411 directory, with the same business and certification status the directory shows.
Radon professionals listed in Westerville: 1 of 5
5 listings with Westerville as the city. See radon mitigation and testing in Westerville, or all radon professionals in Ohio.
Westerville, Local resources
Local resources for Westerville
Who to ask in Ohio: its radon program, test kits and professionals.
What it means
Westerville, Questions
Questions about radon in Westerville
What radon zone is Westerville in?
Both counties Westerville reaches into (Franklin County and Delaware County) are in Zone 1, the map's highest class: a predicted county average above 4 pCi/L. EPA zones counties, not cities, so that is the zone for every part of Westerville.
What are radon levels in Westerville?
High results are ordinary around Westerville: 71.9% of the 16,142 tests reported from Franklin County for 2008 to 2017 (laboratory totals) were at or above 4 pCi/L, the level at which EPA says to fix a home. The median reported result was 6.8 pCi/L. Delaware County reported 72.2% of 3,730 tests; the counties are kept apart.
Should I test my home in Westerville?
Yes. Franklin County reported about 11,606 of its 16,142 tests at or above 4 pCi/L. That is above Ohio's pooled 52.3%, and ranks Franklin County 6th of the 79 Ohio counties with 30 or more tests. Which homes they were, no map can say. How to test a home.
What ground is Westerville built on, as far as radon goes?
USGS's geologic map puts all of Westerville on one named area, "Till Plains", rated high for radon potential, radon index 14.
Is radon higher in the counties around Westerville?
It depends which way you go. 3 of the 8 nearest counties with a figure report a larger share than Franklin County's 71.9% and 5 a smaller one: from Union County (60.2%, 27 miles off) to Pickaway County (81.4%, 34 miles off).
Who tests for or fixes radon in Westerville?
Westerville is the address of 5 businesses in Radon411's directory, 4 listed for testing and 1 for mitigation. Each entry names the public list it came from. Radon professionals in Westerville.
The answers use the published figures of Franklin County and Delaware County, the counties Westerville lies in.
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