2026 Rankings

EPA Radon Zone 1 ZIP Codes in Colorado - 2026

Last updated: August 31, 2026

602 ZIP codes ranked by Radon Zone #1: ZIP 80550 (Windsor, CO) - Zone 1 (highest potential)
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 602 ZIP codes with data in Colorado, these are the lowest-ranked areas for radon zone. See also: National ZIP Codes in EPA Radon Zone 1 | All Colorado Rankings

Statistic Value
ZIP codes ranked 602
Lowest value Zone 1 (highest potential)
Median value Zone 1 (highest potential)
State Colorado

100 Lowest-Ranked ZIP Codes

Rank ZIP Code City State Radon Zone Safety Score
1 80550 Windsor CO Zone 1 (highest potential) 31/100
2 80260 Denver CO Zone 1 (highest potential) 33/100
3 80537 Loveland CO Zone 1 (highest potential) 33/100
4 80817 Fountain CO Zone 1 (highest potential) 33/100
5 81435 Telluride CO Zone 1 (highest potential) 33/100
6 80651 Platteville CO Zone 1 (highest potential) 34/100
7 80504 Longmont CO Zone 1 (highest potential) 35/100
8 80534 Johnstown CO Zone 1 (highest potential) 35/100
9 80543 Milliken CO Zone 1 (highest potential) 36/100
10 80538 Loveland CO Zone 1 (highest potential) 38/100
11 80016 Aurora CO Zone 1 (highest potential) 39/100
12 80108 Castle Rock CO Zone 1 (highest potential) 41/100
13 80134 Parker CO Zone 1 (highest potential) 41/100
14 80603 Brighton CO Zone 1 (highest potential) 41/100
15 80542 Mead CO Zone 1 (highest potential) 42/100
16 80621 Fort Lupton CO Zone 1 (highest potential) 42/100
17 80138 Parker CO Zone 1 (highest potential) 44/100
18 80911 Colorado Springs CO Zone 1 (highest potential) 44/100
19 80221 Denver CO Zone 1 (highest potential) 45/100
20 80513 Berthoud CO Zone 1 (highest potential) 45/100
21 80602 Brighton CO Zone 1 (highest potential) 45/100
22 80112 Englewood CO Zone 1 (highest potential) 47/100
23 80229 Denver CO Zone 1 (highest potential) 47/100
24 80233 Denver CO Zone 1 (highest potential) 47/100
25 80241 Thornton CO Zone 1 (highest potential) 47/100
26 80601 Brighton CO Zone 1 (highest potential) 47/100
27 80640 Henderson CO Zone 1 (highest potential) 47/100
28 80925 Colorado Springs CO Zone 1 (highest potential) 47/100
29 80111 Englewood CO Zone 1 (highest potential) 48/100
30 80124 Lone Tree CO Zone 1 (highest potential) 48/100
31 80928 Colorado Springs CO Zone 1 (highest potential) 48/100
32 80951 Colorado Springs CO Zone 1 (highest potential) 48/100
33 80015 Aurora CO Zone 1 (highest potential) 49/100
34 80503 Longmont CO Zone 1 (highest potential) 49/100
35 80615 Eaton CO Zone 1 (highest potential) 49/100
36 80645 La Salle CO Zone 1 (highest potential) 49/100
37 80915 Colorado Springs CO Zone 1 (highest potential) 49/100
38 80922 Colorado Springs CO Zone 1 (highest potential) 49/100
39 80118 Larkspur CO Zone 1 (highest potential) 50/100
40 80301 Boulder CO Zone 1 (highest potential) 50/100
41 80401 Golden CO Zone 1 (highest potential) 50/100
42 80439 Evergreen CO Zone 1 (highest potential) 50/100
43 80465 Morrison CO Zone 1 (highest potential) 50/100
44 80516 Erie CO Zone 1 (highest potential) 50/100
45 80517 Estes Park CO Zone 1 (highest potential) 50/100
46 80524 Fort Collins CO Zone 1 (highest potential) 50/100
47 80631 Greeley CO Zone 1 (highest potential) 50/100
48 80831 Peyton CO Zone 1 (highest potential) 50/100
49 80903 Colorado Springs CO Zone 1 (highest potential) 50/100
50 80906 Colorado Springs CO Zone 1 (highest potential) 50/100
51 80908 Colorado Springs CO Zone 1 (highest potential) 50/100
52 80910 Colorado Springs CO Zone 1 (highest potential) 50/100
53 80926 Colorado Springs CO Zone 1 (highest potential) 50/100
54 80939 Colorado Springs CO Zone 1 (highest potential) 50/100
55 81004 Pueblo CO Zone 1 (highest potential) 50/100
56 81230 Gunnison CO Zone 1 (highest potential) 50/100
57 80026 Lafayette CO Zone 1 (highest potential) 51/100
58 80132 Monument CO Zone 1 (highest potential) 52/100
59 80612 Carr CO Zone 1 (highest potential) 52/100
60 80127 Littleton CO Zone 1 (highest potential) 53/100
61 80234 Denver CO Zone 1 (highest potential) 53/100
62 80634 Greeley CO Zone 1 (highest potential) 53/100
63 81001 Pueblo CO Zone 1 (highest potential) 53/100
64 81006 Pueblo CO Zone 1 (highest potential) 53/100
65 80514 Dacono CO Zone 1 (highest potential) 54/100
66 80921 Colorado Springs CO Zone 1 (highest potential) 54/100
67 81226 Florence CO Zone 1 (highest potential) 55/100
68 81419 Hotchkiss CO Zone 1 (highest potential) 55/100
69 80520 Firestone CO Zone 1 (highest potential) 56/100
70 80530 Frederick CO Zone 1 (highest potential) 56/100
71 80610 Ault CO Zone 1 (highest potential) 56/100
72 80620 Evans CO Zone 1 (highest potential) 56/100
73 80650 Pierce CO Zone 1 (highest potential) 56/100
74 80305 Boulder CO Zone 1 (highest potential) 57/100
75 80535 Laporte CO Zone 1 (highest potential) 57/100
76 80549 Wellington CO Zone 1 (highest potential) 57/100
77 80642 Hudson CO Zone 1 (highest potential) 57/100
78 80525 Fort Collins CO Zone 1 (highest potential) 58/100
79 80624 Gill CO Zone 1 (highest potential) 58/100
80 80644 Kersey CO Zone 1 (highest potential) 58/100
81 81520 Clifton CO Zone 1 (highest potential) 58/100
82 81526 Palisade CO Zone 1 (highest potential) 58/100
83 81611 Aspen CO Zone 1 (highest potential) 58/100
84 81623 Carbondale CO Zone 1 (highest potential) 58/100
85 80521 Fort Collins CO Zone 1 (highest potential) 59/100
86 80526 Fort Collins CO Zone 1 (highest potential) 59/100
87 81212 Canon City CO Zone 1 (highest potential) 59/100
88 80027 Louisville CO Zone 1 (highest potential) 60/100
89 80303 Boulder CO Zone 1 (highest potential) 60/100
90 80547 Timnath CO Zone 1 (highest potential) 60/100
91 81003 Pueblo CO Zone 1 (highest potential) 60/100
92 81007 Pueblo CO Zone 1 (highest potential) 60/100
93 81008 Pueblo CO Zone 1 (highest potential) 60/100
94 81615 Snowmass Village CO Zone 1 (highest potential) 60/100
95 80116 Franktown CO Zone 1 (highest potential) 61/100
96 81650 Rifle CO Zone 1 (highest potential) 61/100
97 80512 Bellvue CO Zone 1 (highest potential) 62/100
98 80528 Fort Collins CO Zone 1 (highest potential) 62/100
99 80021 Broomfield CO Zone 1 (highest potential) 63/100
100 80109 Castle Rock CO Zone 1 (highest potential) 63/100

Methodology

This ranking is limited to EPA county-level radon zone classification. Zone 1 identifies the highest county-level potential category; it does not measure a home or establish whether any building is above an action level. Within Zone 1, ZIP codes are sub-ranked by Home Safety Score to organize area context.

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: 2026-08-31.

Frequently Asked Questions

What is EPA Radon Zone 1?

Zone 1 is the EPA highest county-level radon-potential category. It is not a measurement for a home and cannot determine whether a building is above an action level. A home test is required for that decision.

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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