Is radon high in New Haven, Connecticut?

Low. Averaging the model's ZIP-code predictions across New Haven (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.2 pCi/L - about 36% below the US average of 1.8 and about 24% below the Connecticut average of 1.5. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. New Haven ranks 10 of 15 Connecticut cities on this site.

Which New Haven ZIP codes have the highest radon?

Predictions for the 5 modeled ZIP codes in New Haven range from 0.9 to 1.4 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.

Should I test for radon in New Haven?

Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; New Haven's low predicted average describes the typical home, not yours.

What does EPA Radon Zone 1 mean for New Haven?

New Haven sits mainly in New Haven County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.2 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

Radon levels in New Haven, Connecticut

LowEPA Zone 1

Predicted long-term basement average of 1.2 pCi/L (model estimate) across the 5 modeled ZIP codes in New Haven - about 36% below the US average of 1.8, about 24% below the Connecticut average of 1.5. Ranked #10 of 15 Connecticut cities on this site. Most of the city lies in New Haven County.

Test New Haven, CT once anyway - radon varies house to house

The predicted basement average here is 1.2 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

1.2 ± 0.06

pCi/L predicted basement mean (model SD)

0.6 ± 0.07

pCi/L predicted upstairs (above-ground) mean

0.9-1.4

range of ZIP-level basement predictions in the city

of New Haven ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)

What this means for New Haven

The typical New Haven home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 0.9 to 1.4 pCi/L.

The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). Note that the EPA classifies New Haven County as Zone 1 while the newer model predicts 1.2 pCi/L for New Haven; where they disagree, we grade on the model but show both.

Comparable Connecticut cities: New Britain (1.2), West Hartford (1.2), West Haven (1.1), Middletown (1.1).

ZIP codes in New Haven

ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.

ZIP	Share of city	Basement	Upstairs	Grade
06511	31%	0.9 ± 0.07	0.5	Low
06515	24%	1.4 ± 0.06	0.7	Low
06513	21%	1.2 ± 0.06	0.6	Low
06512	12%	1.2 ± 0.06	0.6	Low
06519	10%	1.1 ± 0.06	0.5	Low
06510	1%	—	—	no model

Testing help in Connecticut

Connecticut's radon program page is at portal.ct.gov; it lists testing and certified-mitigator guidance. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.

New Haven radon questions

Is radon high in New Haven, Connecticut?: Low. Averaging the model's ZIP-code predictions across New Haven (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.2 pCi/L - about 36% below the US average of 1.8 and about 24% below the Connecticut average of 1.5. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. New Haven ranks 10 of 15 Connecticut cities on this site.
Which New Haven ZIP codes have the highest radon?: Predictions for the 5 modeled ZIP codes in New Haven range from 0.9 to 1.4 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
Should I test for radon in New Haven?: Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; New Haven's low predicted average describes the typical home, not yours.
What does EPA Radon Zone 1 mean for New Haven?: New Haven sits mainly in New Haven County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.2 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

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