2026 Rankings

Highest Radon Risk ZIP Codes in Connecticut — 2026

Last updated: August 14, 2026

216 ZIP codes ranked by Radon Zone #1: ZIP 06482 (Sandy Hook, CT) - Zone 1 (High)
Lead Violations Lowest Score Safest Flood Risk Energy Cost Radon PFAS Reliability EJ Index Homebuyer Risk CO & Gas Safest Gas Remediation Burden Unresolved Violations (by Utility) Water Equity (by Utility)

Out of 216 ZIP codes with data in Connecticut, these are the lowest-ranked areas for radon zone. See also: National ZIP Codes with Highest Radon Risk | All Connecticut Rankings

Statistic Value
ZIP codes ranked 216
Lowest value Zone 1 (High)
Median value Zone 1 (High)
State Connecticut

100 Lowest-Ranked ZIP Codes

Rank ZIP Code City State Radon Zone Safety Score
1 06482 Sandy Hook CT Zone 1 (High) 33/100
2 06488 Southbury CT Zone 1 (High) 33/100
3 06804 Brookfield CT Zone 1 (High) 33/100
4 06810 Danbury CT Zone 1 (High) 33/100
5 06811 Danbury CT Zone 1 (High) 33/100
6 06333 East Lyme CT Zone 1 (High) 36/100
7 06357 Niantic CT Zone 1 (High) 36/100
8 06801 Bethel CT Zone 1 (High) 36/100
9 06410 Cheshire CT Zone 1 (High) 37/100
10 06416 Cromwell CT Zone 1 (High) 37/100
11 06382 Uncasville CT Zone 1 (High) 41/100
12 06415 Colchester CT Zone 1 (High) 41/100
13 06450 Meriden CT Zone 1 (High) 41/100
14 06492 Wallingford CT Zone 1 (High) 41/100
15 06877 Ridgefield CT Zone 1 (High) 42/100
16 06473 North Haven CT Zone 1 (High) 43/100
17 06470 Newtown CT Zone 1 (High) 44/100
18 06455 Middlefield CT Zone 1 (High) 45/100
19 06351 Jewett City CT Zone 1 (High) 46/100
20 06457 Middletown CT Zone 1 (High) 46/100
21 06716 Wolcott CT Zone 1 (High) 46/100
22 06338 Mashantucket CT Zone 1 (High) 47/100
23 06365 Preston CT Zone 1 (High) 47/100
24 06611 Trumbull CT Zone 1 (High) 48/100
25 06762 Middlebury CT Zone 1 (High) 48/100
26 06451 Meriden CT Zone 1 (High) 49/100
27 06850 Norwalk CT Zone 1 (High) 49/100
28 06851 Norwalk CT Zone 1 (High) 49/100
29 06855 Norwalk CT Zone 1 (High) 49/100
30 06883 Weston CT Zone 1 (High) 49/100
31 06897 Wilton CT Zone 1 (High) 49/100
32 06360 Norwich CT Zone 1 (High) 50/100
33 06379 Pawcatuck CT Zone 1 (High) 50/100
34 06401 Ansonia CT Zone 1 (High) 50/100
35 06403 Beacon Falls CT Zone 1 (High) 50/100
36 06405 Branford CT Zone 1 (High) 50/100
37 06413 Clinton CT Zone 1 (High) 50/100
38 06418 Derby CT Zone 1 (High) 50/100
39 06437 Guilford CT Zone 1 (High) 50/100
40 06443 Madison CT Zone 1 (High) 50/100
41 06468 Monroe CT Zone 1 (High) 50/100
42 06471 North Branford CT Zone 1 (High) 50/100
43 06472 Northford CT Zone 1 (High) 50/100
44 06475 Old Saybrook CT Zone 1 (High) 50/100
45 06477 Orange CT Zone 1 (High) 50/100
46 06478 Oxford CT Zone 1 (High) 50/100
47 06483 Seymour CT Zone 1 (High) 50/100
48 06484 Shelton CT Zone 1 (High) 50/100
49 06498 Westbrook CT Zone 1 (High) 50/100
50 06510 New Haven CT Zone 1 (High) 50/100
51 06511 New Haven CT Zone 1 (High) 50/100
52 06512 East Haven CT Zone 1 (High) 50/100
53 06513 New Haven CT Zone 1 (High) 50/100
54 06514 Hamden CT Zone 1 (High) 50/100
55 06515 New Haven CT Zone 1 (High) 50/100
56 06516 West Haven CT Zone 1 (High) 50/100
57 06517 Hamden CT Zone 1 (High) 50/100
58 06518 Hamden CT Zone 1 (High) 50/100
59 06519 New Haven CT Zone 1 (High) 50/100
60 06525 Woodbridge CT Zone 1 (High) 50/100
61 06604 Bridgeport CT Zone 1 (High) 50/100
62 06605 Bridgeport CT Zone 1 (High) 50/100
63 06606 Bridgeport CT Zone 1 (High) 50/100
64 06607 Bridgeport CT Zone 1 (High) 50/100
65 06608 Bridgeport CT Zone 1 (High) 50/100
66 06610 Bridgeport CT Zone 1 (High) 50/100
67 06612 Easton CT Zone 1 (High) 50/100
68 06614 Stratford CT Zone 1 (High) 50/100
69 06615 Stratford CT Zone 1 (High) 50/100
70 06807 Cos Cob CT Zone 1 (High) 50/100
71 06820 Darien CT Zone 1 (High) 50/100
72 06824 Fairfield CT Zone 1 (High) 50/100
73 06825 Fairfield CT Zone 1 (High) 50/100
74 06830 Greenwich CT Zone 1 (High) 50/100
75 06831 Greenwich CT Zone 1 (High) 50/100
76 06870 Old Greenwich CT Zone 1 (High) 50/100
77 06878 Riverside CT Zone 1 (High) 50/100
78 06890 Southport CT Zone 1 (High) 50/100
79 06901 Stamford CT Zone 1 (High) 50/100
80 06903 Stamford CT Zone 1 (High) 50/100
81 06905 Stamford CT Zone 1 (High) 50/100
82 06906 Stamford CT Zone 1 (High) 50/100
83 06907 Stamford CT Zone 1 (High) 50/100
84 06340 Groton CT Zone 1 (High) 55/100
85 06442 Ivoryton CT Zone 1 (High) 60/100
86 06704 Waterbury CT Zone 1 (High) 63/100
87 06708 Waterbury CT Zone 1 (High) 63/100
88 06320 New London CT Zone 1 (High) 64/100
89 06355 Mystic CT Zone 1 (High) 64/100
90 06385 Waterford CT Zone 1 (High) 64/100
91 06712 Prospect CT Zone 1 (High) 64/100
92 06702 Waterbury CT Zone 1 (High) 65/100
93 06705 Waterbury CT Zone 1 (High) 65/100
94 06706 Waterbury CT Zone 1 (High) 65/100
95 06770 Naugatuck CT Zone 1 (High) 65/100
96 06378 Stonington CT Zone 1 (High) 66/100
97 06480 Portland CT Zone 1 (High) 66/100
98 06853 Norwalk CT Zone 1 (High) 66/100
99 06854 Norwalk CT Zone 1 (High) 66/100
100 06409 Centerbrook CT Zone 1 (High) 67/100

Methodology

Radon rankings are based on EPA county-level radon zone classifications. Zone 1 (highest risk) has predicted average indoor radon levels above 4 pCi/L — the EPA action level. Zone 2 is moderate (2-4 pCi/L) and Zone 3 is low (below 2 pCi/L). Within Zone 1, ZIP codes are sub-ranked by Home Safety Score to prioritize areas with compounding risk factors.

Data sources: EPA Safe Drinking Water Information System (SDWIS), FEMA National Flood Insurance Program, EPA radon zone maps, EIA electricity rates, and Consumer Confidence Reports. Last updated: 2026-08-14.

Frequently Asked Questions

What is EPA Radon Zone 1?

Zone 1 is the EPA highest-risk classification, meaning the county has predicted average indoor radon levels above 4 pCi/L — the level at which the EPA recommends mitigation. Radon causes about 21,000 lung cancer deaths per year in the U.S.

Should I test for radon?

The EPA recommends testing all homes regardless of radon zone. A DIY test kit costs $15-40. Professional testing costs $150-250. If levels exceed 4 pCi/L, mitigation systems ($800-2,500) can reduce radon by up to 99%.

Explore More Rankings

How this ranking is calculated, data sources, and limitations: Rankings Methodology →

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Disclaimer: Rankings are based on EPA, FEMA, and federal agency data. They reflect historical patterns and risk indicators, not necessarily current conditions. For the most current information, contact your local water utility or request a Consumer Confidence Report.

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