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Radon Levels in Converse County, Wyoming

EPA puts Converse County in Zone 1, its highest radon zone, and high results are common there: 62.3% of the 130 radon tests reported to CDC (2008 to 2017, laboratory totals) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    62.3%

    18.0 pts above WY

    Converse
    62.3%
    Wyoming
    44.3%

    130 tests, 2008 to 2017

  • Median result

    4.8pCi/L

    Action level reached

    Converse
    4.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    130

    15th of 22 by tests

    Converse
    130
    Laramie
    1,834

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Wyoming

    4 of 22

    Top quarter

    Converse
    62.3%
    Sheridan
    69.5%

    By share, of 22 with 30+ tests

Read a result for Converse County

Starts at Converse County's median, 4.8 pCi/L

4.8pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.8 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Converse County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Converse County, At a glance

Converse County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Converse County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 88% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Converse County, 2008 to 2017, laboratory

Reported results by concentration band, Converse County, 2008 to 2017, laboratory
Under 2 pCi/L: 16%2 to 4 pCi/L: 22%4 pCi/L and above: 62%

Of 130 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Converse County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2116.2%
2 to 4 pCi/L2821.5%
4 pCi/L and above8162.3%
What these figures count

These are the 130 tests reported to CDC for Converse County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Converse County, Compared

Converse County radon figures, compared

Calculated by Radon411

More than half: 62.3% of the 130 radon tests reported to CDC for Converse County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 4th of 22 Wyoming counties with 30 or more tests for the same period. That is 18.0 points above the 44.3% pooled from 23 Wyoming counties.

The median result, 4.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 25.2 pCi/L. The rest split 16.2% under 2 pCi/L and 21.5% from 2 to 4 (Wyoming: 25.5% and 30.2%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 62.3% share point the same way here.

1 of its 7 bordering counties with figures ran higher, led by Weston County at 65.6%; Platte County reported 26.5%. Statewide for the same period, Sheridan County reported the highest share (69.5%) and Uinta County the lowest (24.6%).

CDC's ten-year totals for Converse County went from 126 tests (2005 to 2014) to 130 (2008 to 2017), the share going from 63.5% to 62.3%.

Nationally, every county with a figure for the same period pools to 35.7%; Converse County sits 26.6 points above it. CDC also counts 6 tests taken after mitigation in Converse County for the same period: tests in homes where a fix was already in.

Converse County against Wyoming, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Converse County
Converse County13062.3%4.8 pCi/LThis county
Wyoming, pooled23 counties, pooled7,63844.3%Not pooled−18.0 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−26.6 points
Sheridan Countyhighest in the state84669.5%5.8 pCi/L+7.2 points
Uinta Countylowest in the state19924.6%2.2 pCi/L−37.7 points
Weston County, WYborders it3265.6%6.3 pCi/L+3.3 points
Natrona County, WYborders it1,05455.7%4.3 pCi/L−6.6 points
Campbell County, WYborders it27143.9%3.5 pCi/L−18.4 points
Carbon County, WYborders it8041.3%3.0 pCi/L−21.0 points
Johnson County, WYborders it13534.8%3.1 pCi/L−27.5 points
Albany County, WYborders it39427.9%2.7 pCi/L−34.4 points
Platte County, WYborders it13226.5%2.4 pCi/L−35.8 points
Niobrara County, WYborders it1225.0%3.5 pCi/L−37.3 points
Where Converse County's reported results fell, 2008 to 2017, laboratory, beside Wyoming and the United States
ResultConverse County testsConverse County shareWyoming shareU.S. shareAgainst Wyoming
Under 2 pCi/L2116.2%25.5%39.6%−9.3 points
2 to 4 pCi/L2821.5%30.2%24.7%−8.7 points
4 pCi/L and above8162.3%44.3%35.7%+18.0 points
Converse County ranked among the 22 Wyoming counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Sheridan County1 of 2284669.5%5.8 pCi/L
Lincoln County2 of 2214268.3%7.8 pCi/L
Weston County3 of 223265.6%6.3 pCi/L
Converse County4 of 2213062.3%4.8 pCi/L
Crook County5 of 225158.8%5.1 pCi/L
Hot Springs County6 of 225955.9%4.2 pCi/L
Natrona County7 of 221,05455.7%4.3 pCi/L
Fremont County8 of 2261855.7%4.7 pCi/L
Sublette County9 of 226050.0%4.0 pCi/L
Sweetwater County10 of 2240949.6%3.9 pCi/L
Teton County11 of 2227844.6%3.4 pCi/L
Converse County ten-year laboratory totals, against Wyoming's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestWyoming, pooledChange from the row before
2008 to 201713062.3%4.8 pCi/L25.2 pCi/L44.3%−1.3 points
2007 to 201612963.6%4.8 pCi/L25.2 pCi/L44.6%−0.2 points
2006 to 201512763.8%4.7 pCi/L25.2 pCi/L45.3%+0.3 points
2005 to 201412663.5%4.8 pCi/L25.2 pCi/L45.5%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Converse County, Geology

The ground under Converse County

Predicted

Most of the ground under Converse County is one class on USGS's geologic map: 87.5% of its land is high radon potential, with 12.5% moderate. The map puts 63.0% of Converse County in the area it calls Powder River Basin and 16.9% in Laramie Mountains, with 4 smaller areas beside them. USGS gives both a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Converse County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Powder River BasinCretaceous and Tertiary uranium-bearing marginal-marine and fluvial sandstones.High1263.0%
Laramie MountainsPrecambrian anorthosite, monzonite, gneissic granite, and granite.High1216.9%
Casper Arch AreaUpper Cretaceous marine sedimentary rocks.Moderate116.3%
Tertiary RocksTertiary sandstone, siltstone, and volcanic ash.Moderate116.1%
Wind River BasinCretaceous and Tertiary uranium-bearing marginal-marine and fluvial sandstones.High125.8%
Hartville UpliftPrecambrian granite and metasedimentary rocks.High121.8%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Converse County beside the ground around it

Converse County has more high-potential ground than Wyoming as a whole: 87.5% of its land against 72.4%. Of the 8 counties that border it, 2 have more high-potential ground, Albany County the most at 99.7%.

Share of land by USGS radon potential: Converse County, the 8 counties bordering it and Wyoming
AreaEPA zoneLow potentialModerate potentialHigh potential
Converse CountyZone 1None12.5%87.5%
Niobrara CountyZone 1None69.5%30.5%
Weston CountyZone 2None54.9%45.1%
Platte CountyZone 2None69.9%30.1%
Natrona CountyZone 1None39.4%60.6%
Johnson CountyZone 1None14.4%85.6%
Campbell CountyZone 1None2.4%97.6%
Albany CountyZone 1None0.3%99.7%
Carbon CountyZone 1None29.2%70.8%
Wyoming23 counties, pooled by land areaVariesNone27.6%72.4%

The map rates the ground, not the air in any home.

Local help

Converse County, Local resources

Radon testing and mitigation in Converse County

What it means

Converse County, Questions

Questions about radon in Converse County

Are radon levels high in Converse County?

Over the 2008 to 2017 laboratory totals, 62.3% of the radon tests reported to CDC for Converse County, Wyoming were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.8 pCi/L. Of 22 Wyoming counties with 30 or more tests for the same period, 3 reported a higher share; pooled, the state comes to 44.3%.

Which counties border Converse County?

Converse County borders 8 counties: Niobrara County, Weston County, Platte County, Natrona County, Johnson County, Campbell County, Albany County and Carbon County.

Products

Converse County, Products

Testing a home in Converse County

In Converse County, 62.3% of 130 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 44.3% pooled across Wyoming. In Zone 1 the year-round level in Converse County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Converse County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Converse County

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Converse County, Bordering counties

Counties bordering Converse County

Calculated by Radon411

Converse County, Cities and towns

Cities and towns in Converse County

The Census Bureau estimates 13,824 residents in Converse County for July 1, 2025, 76 more than in 2020 (+0.6%). Spread over its land, that is 3.2 people to the square mile. Its largest town, Douglas, has 6,469 residents, 46.8% of the total. Together its 4 incorporated places hold 67.4% of those residents; the other 32.6% live outside any of them. CDC's 130 reported tests for 2008 to 2017 work out to 9.4 per 1,000 residents (2025 estimate), close to Wyoming's 13.0.

From Douglas to Lost Springs, CDC publishes no figure by town: each reads Converse County's.

The cities and towns in Converse County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Douglas6,469+1.2%46.8%
Glenrock2,418−0.1%17.5%
Rolling Hills428−0.5%3.1%
Lost Springs3LevelUnder 0.1%

4 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

Converse County, Homes

Homes in Converse County

Of Converse County's 6,643 homes, 71% are detached houses, against 68% across Wyoming; 12% are mobile homes. Half of its homes were built before 1978, close to Wyoming's 1980: 19% date from before 1960 and 24% from 2000 or later. Owners live in 78% of the occupied homes (Wyoming: 72%), so for most households a test and a fix are their own to order.

Homes in Converse County, Wyoming, 2019 to 2023
HomesConverse CountyWyoming
Housing units6,643275,131
Detached houses71%68%
In buildings of 5 or more9%9%
Mobile homes12%12%
Built before 196019%24%
Built since 200024%24%
Middle year built19781980
Owner-occupied78%72%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.