Radon · ZIP 52240
Radon in Iowa City (IA), IA
ZIP 52240 (Iowa) — radon summary sourced from EPA Radon Zones. Refreshed on the cadence of the primary regulator with every claim cited to the source record.
Johnson County (IA), Iowa
Zone 1 — highest potential
The EPA Map of Radon Zones classifies Johnson County (IA) 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 52240.
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.
What lands here
The county-level classification and EPA's own testing guidance for this ZIP's county — shown above.
Source & refresh
EPA Radon Zones. Refreshed static 1993 baseline plus state-level supplementary updates. Stale data is flagged, never silently served. 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).
Iowa context
Radon Zone 1, agricultural water nitrates
Iowa is one of the highest-radon states in the US — uniformly Zone 1. Agricultural runoff drives EPA SDWIS nitrate violations in small rural systems and even Des Moines Water Works. Tornadoes peak April-June.
See Iowa 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 52240
Radon is one of twelve public-records dimensions zipradar indexes per address. See the ZIP 52240 index for the other eleven — each with its own regulator, source and link:
All dimensions for Iowa City (IA), IA →Frequently asked questions
What is the radon for ZIP 52240?
Johnson County (IA), Iowa (which covers ZIP 52240) 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?
EPA Radon Zones (primary regulator). zipradar federates radon on the regulator's published cadence: static 1993 baseline plus state-level supplementary updates. Every claim cites the source record; stale data is flagged, never silently served. The primary source URL: 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 52240 (Iowa City (IA)) data current?
Last verified 2026-09-07. Radon for ZIP 52240 refreshes static 1993 baseline plus state-level supplementary updates per EPA Radon Zones cadence. See the full ZIP dashboard at /zip/52240/ for all 12 dimensions side-by-side.