Listed for: Testing
Verified:Ohio state license
Call 1st Inspection Services at (937) 684-9544No website listed
Locations and reports
Radon in Dayton, Ohio
Dayton lies in 2 counties, in EPA Zone 1; 100% of it is in Montgomery County, where 50.3% of 2,922 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
50.3%
2.0 pts below OH
- Montgomery
- 50.3%
- Ohio
- 52.3%
Montgomery, 46th of 79 in OH, 2008 to 2017
Median result
4.0pCi/L
Action level reached
- Montgomery
- 4.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Montgomery's tests, 2008 to 2017
Highest county
58.6%
Greene
- Greene
- 58.6%
- Montgomery
- 50.3%
2 counties, 2 with 30+ tests, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
Montgomery; Greene Zone 1
Tests reported
2,922
In Montgomery
- Montgomery
- 2,922
- Greene
- 2,602
Reported to CDC before any fix, 2008 to 2017
Read a result for Dayton
Starts at Montgomery County's median, 4.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 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. Montgomery County's median reported result, 2008 to 2017.
The data
Dayton, What is published
What is published for Dayton
Information:
Every figure for Dayton is a county's
Radon data is published by county, not by city, and Dayton reaches into 2 counties: Montgomery County and Greene 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.
Dayton covers 55.8 square miles of land, all of it in Montgomery County. About 136,688 people live there, 2,449 to the square mile.
Dayton, Counties
Dayton'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.
- Montgomery County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 50.3%
- Median result
- 4.0 pCi/L
- Tests reported
- 2,922 tests
- Annual years on file
- None
- Greene County
- EPA zone
- Zone 1: Highest predicted potential
- At or above 4 pCi/L
- 58.6%
- Median result
- 4.9 pCi/L
- Tests reported
- 2,602 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 |
|---|---|---|---|---|---|
| Montgomery County | Zone 1: Highest predicted potential | 50.3% | 4.0 pCi/L | 2,922 tests | None |
| Greene County | Zone 1: Highest predicted potential | 58.6% | 4.9 pCi/L | 2,602 tests | None |
Dayton spans 2 counties, each with its own EPA zone and its own CDC figure: Montgomery County (Zone 1, 50.3% of 2,922 tests) and Greene County (Zone 1, 58.6% of 2,602 tests).
Montgomery County ranks 46th of 79 Ohio counties with 30 or more tests for that period, 2.0 points below the 52.3% pooled across Ohio's counties, 14.6 points above the national pool of 35.7%. Of the city's other county, Greene County reported 58.6%.
The counties nearest Dayton with a CDC figure for 2008 to 2017, laboratory, measured from the middle of the city: Miami County (19 miles, 65.2% of 690 tests), Preble County (24 miles, 62.7% of 212 tests) and Clark County (24 miles, 57.5% of 1,447 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 52.4% to 71.1%; the farthest of them, Champaign County, is 34 miles away at 71.1%.
The directory lists 15 businesses with an address in Dayton, 13 for testing and 3 for mitigation. Ohio's other cities with a page of their own: Columbus, Cincinnati, Toledo and Cleveland.
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 Dayton
By distance from the middle of Dayton; counties with 30 or more tests.
The median reported pre-mitigation result for 2008 to 2017, laboratory was 4.0 pCi/L in Montgomery County and 4.9 pCi/L in Greene County.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.
Dayton, Geology
The ground under Dayton
PredictedUSGS's geologic map puts all of Dayton'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.
Dayton beside its counties and Ohio
All of Dayton, like all of Montgomery County, is rated high. Dayton 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.
Dayton, Homes
Homes in Dayton
Of Dayton's 69,640 homes, 63% are detached houses, against 67% across Montgomery County; 20% are in buildings of five or more homes. The homes are older than Montgomery County's as a whole: half were built before 1951 (1966 for Montgomery County), and 65% date from before 1960. Most occupied homes here are rented: owners live in 48% (Montgomery County: 62%). A tenant can run a test; a fix is the landlord's to make.
| Homes | Dayton | Montgomery County | Ohio |
|---|---|---|---|
| Housing units | 69,640 | 252,475 | 5,271,573 |
| Detached houses | 63% | 67% | 69% |
| In buildings of 5 or more | 20% | 16% | 15% |
| Mobile homes | 1% | 1% | 4% |
| Built before 1960 | 65% | 40% | 38% |
| Built since 2000 | 6% | 9% | 16% |
| Middle year built | 1951 | 1966 | 1970 |
| Owner-occupied | 48% | 62% | 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
Dayton, Professionals
Radon professionals listed in Dayton
Businesses whose listed city is Dayton, from the state registries and listings in the Radon411 directory, with the same business and certification status the directory shows.
Radon professionals listed in Dayton: 1 of 6
15 listings with Dayton as the city. See radon mitigation and testing in Dayton, or all radon professionals in Ohio.
Dayton, Local resources
Local resources for Dayton
Who to ask in Ohio: its radon program, test kits and professionals.
What it means
Dayton, Questions
Questions about radon in Dayton
What radon zone is Dayton in?
Both counties Dayton reaches into (Montgomery County and Greene 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 Dayton.
What are radon levels in Dayton?
50.3% of the 2,922 tests reported from Montgomery County for 2008 to 2017 (laboratory totals) were at or above 4 pCi/L, the level at which EPA says to fix a home: high results are ordinary around Dayton. The median reported result was 4.0 pCi/L. Greene County reported 58.6% of 2,602 tests; the counties are kept apart.
Should I test my home in Dayton?
Yes. About 1,470 of the 2,922 tests reported from Montgomery County were at or above 4 pCi/L. That is about what Ohio as a whole reports (52.3%), and ranks Montgomery County 46th of the 79 Ohio counties with 30 or more tests. No map says which homes those are. How to test a home.
What ground is Dayton built on, as far as radon goes?
USGS's geologic map puts all of Dayton on one named area, "Till Plains", rated high for radon potential, radon index 14.
Is radon higher in the counties around Dayton?
Yes, in every direction measured. Each of the 8 nearest counties with a figure reports a larger share of high tests than Montgomery County's 50.3%; the highest is Champaign County (71.1%, 34 miles off).
Who tests for or fixes radon in Dayton?
Radon411's directory has 15 businesses with an address in Dayton, 13 listed for testing and 3 for mitigation. Every entry names the public list it was taken from. Radon professionals in Dayton.
The answers use the published figures of Montgomery County and Greene County, the counties Dayton lies in.
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