Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
Locations and reports
Radon Levels in Nassau County, New York
EPA puts Nassau County in Zone 3, its lowest radon zone, and only 7 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
5.6%
19.3 pts below NY
- Nassau
- 5.6%
- New York
- 24.9%
646 tests, 2007 to 2016
Median result
1.0pCi/L
Below action level
- Nassau
- 1.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2007 to 2016
Tests reported
646
35th of 61 by tests
- Nassau
- 646
- Erie
- 12,998
Reported to CDC before any fix, 2007 to 2016
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Rank in New York
58 of 61
Lowest quarter
- Nassau
- 5.6%
- Chemung
- 51.7%
By share, of 61 with 30+ tests
Read a result for Nassau County
Starts at Nassau County's median, 1.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.0 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Nassau County's median reported result, 2007 to 2016.
The data
Nassau County, At a glance
Nassau County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 86% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Nassau County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 15.4% |
| 2015 | 10.0% |
| 2016 | 9.1% |
| 2017 | 42.9% |
| 2018 | 10.0% |
| 2019 | 0.0% |
| 2020 | 0.0% |
| 2022 | 0.0% |
| 2023 | 0.0% |
2023: 0.0%. Across these years the share ran from 0.0% to 42.9%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 7 tests were reported to CDC for Nassau County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Nassau County, Compared
Nassau County radon figures, compared
Calculated by Radon411Nassau County reports fewer high tests than New York overall. 5.6% of its 646 tests over the 2007 to 2016 laboratory totals were at or above 4 pCi/L. That is 19.3 points below the 24.9% pooled from 62 New York counties.
The newest figure, in 2023, counts only 7 tests (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 646-test figure.
Ordered from highest share down, it comes 58th of 61 New York counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.8%; Nassau County sits 30.2 points below it.
Next door, the shares run from 5.1% in Queens County to 8.3% in Suffolk County, with Queens County below Nassau County. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 5.6% share point the same way here.
Half the tests came in under 1.0 pCi/L and half over it; the single highest reached 318.6 pCi/L. The rest split 81.6% under 2 pCi/L and 12.8% from 2 to 4 (New York: 51.6% and 23.5%).
The busiest year on file was 2016, with 22 tests reported; the quietest, 2020, had 3.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Nassau County, State data
New York's own radon test data
MeasuredWhat New York's own agencies publish about radon tests in Nassau County, with their period. These are not CDC's figures and are never added to them.
MeasuredState figures, not CDC's
What the New York State Department of Health reports for Nassau County
Indoor air radon testing data (Environmental Public Health Tracker): short-term charcoal canister tests requested through the NYSDOH Radon Program, presented as five-year rolling averages. Period: 2015-2019. The publisher also lists 15 earlier periods.
Share at or above 4 pCi/L
16.2%
Average result
1.7 pCi/L
Tests behind these figures
10.8 tests a year on average
- Every figure is a five-year rolling average: the average result is the rolling average of each year's mean, and the test count is an average per year.
- The data only include tests requested through the NYSDOH Radon Program, and therefore may not capture all radon tests performed in a county.
- The data include both screening tests and post-mitigation tests, as it is not always possible to tell them apart.
- Radon testing by homeowners is optional in New York, so the values may not be representative of every home in the county.
- These figures describe tests reported to the New York State Department of Health in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.
Measured: New York State Department of Health data, 2015-2019.
Nassau County, Geology
The ground under Nassau County
PredictedUSGS's geologic map puts all of Nassau County's mapped land in one class: low radon potential. 85.9% of it lies in the area the map calls Atlantic Coastal Plain, to which USGS gives a radon index of 7, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Atlantic Coastal Plain | Glacial deposits and marine sediments. | Low | 7 | 85.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Nassau County beside the ground around it
Across New York 48.9% of the land is rated high; none of Nassau County's is. None of the 2 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Nassau County, Local resources
Radon testing and mitigation in Nassau County
- Radon ProgramRadon Program, run by New York State Department of Health, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in New York.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Providing patients with information about how low-cost test kits may be obtained from the Radon Program.
- Compare kits
- Professionals in New York88 professionals are listed in New York.
What New York's program says
- Phone
- 518-402-7556
- radon@health.ny.gov
- Licensing of radon professionals
NYS does not certify or license radon testers.
What it means
Nassau County, Questions
Questions about radon in Nassau County
Are radon levels high in Nassau County?
In 2023, 0.0% of the radon tests reported to CDC for Nassau County, New York were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.7 pCi/L. Of 61 New York counties with 30 or more tests for the same period, 57 reported a higher share; pooled, the state comes to 24.9%.
Which counties border Nassau County?
Nassau County borders 2 counties: Queens County and Suffolk County.
Products
Nassau County, Products
Testing a home in Nassau County
In Nassau County, 5.6% of 646 tests reported to CDC over the 2007 to 2016 laboratory totals reached 4 pCi/L, against 24.9% pooled across New York. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Nassau County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-1011S rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 12 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Nassau County, Bordering counties
Counties bordering Nassau County
Calculated by Radon411- Radon levels in Suffolk CountyEPA zone 3
8.3%at or above 4 pCi/L
Median 1.1 pCi/L · 577 tests · 2.7 points above Nassau County
- Radon levels in Queens CountyEPA zone 3
5.1%at or above 4 pCi/L
Median 0.8 pCi/L · 408 tests · 0.5 points below Nassau County
Nassau County, Cities and towns
Cities and towns in Nassau County
The Census Bureau estimates 1,398,939 residents in Nassau County for July 1, 2025, 7,987 more than in 2020 (+0.6%). Packed into its land, that is 4,916 people per square mile. No town dominates: Hempstead, the largest, has 59,819 residents, 4.3% of the total. Together its 66 incorporated places hold 38.6% of those residents; the other 61.4% live outside any of them. Reported testing is thin here: 646 tests over 2007 to 2016, or 0.5 for every 1,000 residents (2025 estimate), where New York as a whole comes to 4.6.
From Hempstead to Cove Neck, CDC publishes no figure by town: each reads Nassau County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Hempstead | 59,819 | +1.6% | 4.3% |
| Freeport | 44,174 | −0.3% | 3.2% |
| Valley Stream | 40,379 | −0.2% | 2.9% |
| Long Beach | 34,918 | +0.3% | 2.5% |
| Glen Cove | 28,190 | −0.2% | 2.0% |
| Rockville Centre | 25,770 | −0.4% | 1.8% |
| Garden City | 23,043 | −0.7% | 1.6% |
| Mineola | 21,376 | +2.5% | 1.5% |
| Lynbrook | 20,855 | +2.0% | 1.5% |
| Massapequa Park | 16,997 | −0.3% | 1.2% |
| Floral Park | 16,105 | −0.1% | 1.2% |
| Westbury | 15,981 | +1.1% | 1.1% |
- Great Neck
- New Hyde Park
- East Rockaway
- Farmingdale
- Malverne
- Great Neck Plaza
- Williston Park
- Cedarhurst
- East Hills
- Manorhaven
- Lawrence
- Bayville
- Kings Point
- North Hills
- Old Westbury
- Island Park
- Sea Cliff
- Flower Hill
- Muttontown
- Port Washington North
- Great Neck Estates
- Brookville
- Roslyn
- Lake Success
The other 30 places in Nassau County
- Munsey Park
- Thomaston
- Sands Point
- East Williston
- Oyster Bay Cove
- Old Brookville
- Laurel Hollow
- Stewart Manor
- Lattingtown
- Upper Brookville
- South Floral Park
- Atlantic Beach
- Plandome
- Roslyn Estates
- Hewlett Harbor
- Kensington
- Bellerose
- Roslyn Harbor
- Plandome Heights
- Baxter Estates
- Mill Neck
- Saddle Rock
- Russell Gardens
- Woodsburgh
- Matinecock
- Plandome Manor
- Hewlett Neck
- Hewlett Bay Park
- Centre Island
- Cove Neck
66 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).
Nassau County, Homes
Homes in Nassau County
Nassau County is a place of houses on their own lots: 76% of its 477,860 homes are detached single-family houses, against 41% across New York. Half of its homes were built before 1955, close to New York's 1958: 67% date from before 1960 and 7% from 2000 or later. Owners live in 82% of the occupied homes (New York: 54%), so for most households a test and a fix are their own to order.
| Homes | Nassau County | New York |
|---|---|---|
| Housing units | 477,860 | 8,539,536 |
| Detached houses | 76% | 41% |
| In buildings of 5 or more | 13% | 34% |
| Mobile homes | under 1% | 2% |
| Built before 1960 | 67% | 53% |
| Built since 2000 | 7% | 12% |
| Middle year built | 1955 | 1958 |
| Owner-occupied | 82% | 54% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.