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Radon in Manchester, New Hampshire

EPA puts Hillsborough County, where Manchester is, in Zone 2, its middle radon zone, and high results are common there: 41.5% of the 610 radon tests reported to CDC (2021) 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

    41.5%

    1.2 pts below NH

    Hillsborough
    41.5%
    NH
    42.7%

    Hillsborough, 6th of 10 in NH, 2021

  • Median result

    3.2pCi/L

    Below action level

    Hillsborough
    3.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Hillsborough's tests, 2021

  • Nearest county

    48.1%

    Rockingham, 16 miles

    Rockingham
    48.1%
    Hillsborough
    41.5%

    638 tests, 2021

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    Hillsborough, where Manchester is

  • Tests reported

    610

    In Hillsborough

    Hillsborough
    610
    Rockingham
    638

    Reported to CDC before any fix, 2021

Read a result for Manchester

Starts at Hillsborough County's median, 3.2 pCi/L

3.2pCi/L

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

EPA’s reading of 3.2 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Hillsborough County's median reported result, 2021.

Interpret this readingWhat a fix costs

The data

Manchester, What is published

What is published for Manchester

Information:

Every figure for Manchester is a county's

Radon data is published by county, not by city, so for Manchester it is Hillsborough County's: its EPA zone (Zone 2) and the 610 tests reported to CDC for 2021. Only a test tells you about one home.

Manchester covers 33.1 square miles of land, all of it in Hillsborough County. About 116,818 people live there, 3,532 to the square mile.

Manchester, Counties

The county Manchester lies in

Measured

Hillsborough County's EPA zone and the figures CDC publishes for it, 2021.

Hillsborough CountyZone 2Moderate predicted potential

41.5%
Reported tests at or above 4 pCi/L
3.2 pCi/L
Median reported result
610 tests
Tests reported to CDC
4
Annual years on file

Hillsborough County ranks 6th of 10 New Hampshire counties with 30 or more tests for that period, 1.2 points below the 42.7% pooled across New Hampshire's counties, 17.1 points above the national pool of 24.4%.

The counties nearest Manchester with a CDC figure for 2021, measured from the middle of the city: Rockingham County (16 miles, 48.1% of 638 tests), Merrimack County (25 miles, 31.6% of 187 tests) and Strafford County (30 miles, 47.9% of 213 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 19.4% to 54.0%; the farthest of them, Grafton County, is 69 miles away at 44.4%.

No business in the directory gives Manchester as its address; the New Hampshire list covers it.

The counties around Manchester

By distance from the middle of Manchester; counties with 30 or more tests.

Nearest counties to Manchester with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Rockingham County16 mi63848.1%3.7 pCi/L
Merrimack County25 mi18731.6%2.2 pCi/L
Strafford County30 mi21347.9%3.6 pCi/L
Belknap County37 mi10236.3%2.6 pCi/L
Cheshire County41 mi10319.4%2.1 pCi/L
Sullivan County47 mi6023.3%2.7 pCi/L
Carroll County63 mi16154.0%4.3 pCi/L
Grafton County69 mi14244.4%3.0 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2021.

Manchester, Geology

The ground under Manchester

Predicted

Most of the ground under Manchester is one class on USGS's geologic map: 99.1% of its land is high radon potential, with 0.9% moderate. 99.1% of it lies in the area the map calls Eastern New England Upland, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Manchester
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Eastern New England UplandSilurian-Devonian intrusive rocks ranging from gabbro to granite and Devonian-Carboniferous two-mica granite.High1399.1%
Coastal Lowlands/Eastern New England UplandLate Precambrian metamorphic rocks.Moderate100.9%

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

Manchester beside its county and New Hampshire

Manchester sits on more high-potential ground than Hillsborough County as a whole: 99.1% of the city against 20.4% of the county. Manchester has more high-potential ground than New Hampshire as a whole: 99.1% of its land against 18.8%.

Share of land by USGS radon potential: Manchester, the county it lies in and New Hampshire
AreaEPA zoneLow potentialModerate potentialHigh potential
ManchesterBy countyNone0.9%99.1%
Hillsborough CountyZone 217.8%61.7%20.4%
New Hampshire10 counties, pooled by land areaVaries9.6%71.4%18.8%

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

Manchester, Homes

Homes in Manchester

Manchester has 52,391 homes, and many share a building: 33% are in buildings of five or more, 36% are detached houses, against 57% across Hillsborough County. The homes are older than Hillsborough County's as a whole: half were built before 1964 (1977 for Hillsborough County), and 47% date from before 1960. Most occupied homes here are rented: owners live in 49% (Hillsborough County: 68%). A tenant can run a test; a fix is the landlord's to make.

Homes in Manchester, Hillsborough County, New Hampshire, 2019 to 2023
HomesManchesterHillsborough CountyNew Hampshire
Housing units52,391176,753644,253
Detached houses36%57%63%
In buildings of 5 or more33%21%15%
Mobile homes1%2%5%
Built before 196047%29%29%
Built since 200011%15%18%
Middle year built196419771978
Owner-occupied49%68%73%

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

Local help

Manchester, Local resources

Local resources for Manchester

Who to ask in New Hampshire: its radon program, test kits and professionals.

The program's own words on licensing are on the New Hampshire page.

What it means

Manchester, Questions

Questions about radon in Manchester

What radon zone is Manchester in?

EPA's map puts Hillsborough County, and with it Manchester, in Zone 2, the map's middle class: a predicted county average of 2 to 4 pCi/L.

What are radon levels in Manchester?

41.5% of the 610 tests reported from Hillsborough County for 2021 were at or above 4 pCi/L, the level at which EPA says to fix a home: high results are ordinary around Manchester. The median reported result was 3.2 pCi/L.

Should I test my home in Manchester?

Yes. About 253 of the 610 tests reported from Hillsborough County were at or above 4 pCi/L. That is about what New Hampshire as a whole reports (42.7%), and ranks Hillsborough County 6th of the 10 New Hampshire counties with 30 or more tests. No map says which homes those are. How to test a home.

What ground is Manchester built on, as far as radon goes?

USGS's geologic map puts all of Manchester on one named area, "Eastern New England Upland", rated high for radon potential, radon index 13.

Is radon higher in the counties around Manchester?

Some are and some are not. Against Hillsborough County's 41.5%, 4 of the 8 nearest counties with a figure report more and 4 less, from Cheshire County (19.4%, 41 miles off) to Carroll County (54.0%, 63 miles off).

The answers use the published figures of Hillsborough County, the county Manchester lies in.

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