Radon · ZIP 58103
Radon in Fargo (South), ND
ZIP 58103 is in Cass County, North Dakota, which the EPA Map of Radon Zones places in Zone 1: highest potential, with a predicted average indoor radon screening level greater than 4 pCi/L. That is a county-wide estimate, not a reading from any home, and EPA advises testing every home whatever its zone.
Cass County (ND), North Dakota
Zone 1 — highest potential
The EPA Map of Radon Zones classifies Cass County (ND) as Zone 1 — a predicted average indoor radon screening level greater than 4 pCi/L. This is a county-level, 1993-baseline planning classification, not a measurement of any individual address in ZIP 58103.
The Map of Radon Zones should not be used to determine if individual homes need to be tested. No matter where you live, test your home for radon — it's easy and inexpensive.
Next step for your own home
What this page shows
The county-level classification and EPA's own testing guidance for this ZIP's county — shown above.
Source & refresh
EPA Radon Zones. The EPA Map of Radon Zones was published in 1993 and EPA does not update it on a schedule, so the zone shown here is the current official one. Primary source →
Limitations specific to this source
Radon is a regional indicator. Address-level radon measurement requires an at-home test kit (often free from state health departments).
North Dakota context
Radon Zone 1, flooding (Red River), wind
North Dakota is uniformly Zone 1 radon. Red River of the North FEMA AE zones affect Fargo, Grand Forks. Wind exposure is significant statewide.
See North Dakota state page for the full state-level rollup across all 12 dimensions.
Read more on radon
Editorial deep-dives explaining the source data, its limits, and how to read it.
EPA Radon Zones — what 1, 2, and 3 mean and when you should test
EPA classifies every US county into Zone 1 (high), Zone 2 (moderate), or Zone 3 (low) for radon. Plain-English guide to the classifications and at-home testing.
EPA SDWIS — how to read drinking-water violations and what they actually mean
Plain-English guide to EPA SDWIS drinking-water violations: health-based vs. monitoring vs. reporting violations, MCLs, and what triggers a public notice.
Radon and real estate — what disclosure laws and home tests actually require
What home sellers must disclose about radon by state, when home tests are required, and how to interpret radon-mitigation systems if a home you're buying has one.
Radon disclosure during real-estate transactions — state-by-state
Whether sellers must disclose known radon results varies by state. Quick map of mandatory-disclosure states + what to ask for during inspection.
The other dimensions for ZIP 58103
Radon is one of twelve public-records dimensions zipradar indexes per address. See the ZIP 58103 index for the other eleven — each with its own regulator, source and link:
All dimensions for Fargo (South), ND →Frequently asked questions
What is the radon for ZIP 58103?
Cass County (ND), North Dakota (which covers ZIP 58103) is classified as EPA Radon Zone 1 — a predicted average indoor radon screening level greater than 4 pCi/L. This is a county-level, 1993-baseline planning classification, not an address-level measurement. The Map of Radon Zones should not be used to determine if individual homes need to be tested. No matter where you live, test your home for radon — it's easy and inexpensive.
Where does the radon data come from?
Source: EPA Radon Zones. The EPA Map of Radon Zones was published in 1993 and EPA does not update it on a schedule, so the zone shown here is the current official one. The original is at https://www.epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information.
What are the limitations of radon data?
Radon is a regional indicator. Address-level radon measurement requires an at-home test kit (often free from state health departments).
Is ZIP 58103 (Fargo (South)) data current?
zipradar last checked this page against the source on 2026-09-24. The EPA Map of Radon Zones was published in 1993 and EPA does not update it on a schedule, so the zone shown here is the current official one. The ZIP 58103 overview at /zip/58103/ lists the other topics zipradar covers for this ZIP.