Radon in Maricopa County, Arizona
Maricopa County, Arizona, is in EPA radon Zone 2: predicted average indoor radon screening level from 2 to 4 pCi/L (moderate potential). Radon laboratories reported 1,512 building tests here for 2008 to 2017: median 1.6 pCi/L, with 17.4% at or above EPA's 4 pCi/L action level (Arizona 16.8%, US 36.5%).
Radon test results in Maricopa County
| Test results | Period | Tests | Typical result | 4 pCi/L or more |
|---|---|---|---|---|
| Radon testing laboratories | 2008-2017 | 1,512 | median 1.6 pCi/L | 17.4% |
| Arizona, all counties (labs) | 2008-2017 | 2,229 | n/a | 16.8% |
| United States (labs) | 2008-2017 | 1,408,802 | n/a | 36.5% |
Test results describe buildings whose owners chose to test and whose results reached the lab or agency, not a random sample; small counts swing widely. State and US shares are computed from county counts and percents. The laboratory data comes from national radon testing laboratories and supplements EPA's zone map.
Radon in nearby counties
| County | EPA zone | Lab tests | 4 pCi/L or more |
|---|---|---|---|
| Pinal County, AZ | Zone 2 | 74 | 8.9% |
| Yavapai County, AZ | Zone 2 | 187 | 16.2% |
| Yuma County, AZ | Zone 2 | 8 | 0% |
| La Paz County, AZ | Zone 2 | n/a | n/a |
| Pima County, AZ | Zone 2 | 219 | 6.8% |
| Gila County, AZ | Zone 2 | 8 | 64.7% |
The six counties with the nearest centers.
What to do about radon in Maricopa County
Test the building. EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, and says there is no known safe level of exposure. Arizona's state radon program can point you to testers and test kits.
Buying here? The Environmental Records Report lists this county's radon zone and test results with the flood zone, mapped faults, power lines and federal contamination records near the address.
HeritageDeed searches title in Maricopa County: Order a Maricopa County title search, owner of record, deeds, mortgages and liens, $49 per report.
Radon in Maricopa County: questions
What is the radon level in Maricopa County?
The median of the 1,512 laboratory tests reported for Maricopa County (2008 to 2017) was 1.6 pCi/L, and 17.4% of them were at or above 4 pCi/L. These are results of tested buildings; a single home can be far above or below them.
Is Maricopa County in radon Zone 1?
No. EPA's 1993 map puts Maricopa County in Zone 2 (predicted average indoor radon screening level from 2 to 4 pCi/L (moderate potential)). EPA says homes in every zone can have high radon and should be tested.
How does radon in Maricopa County compare with Arizona?
17.4% of laboratory tests in Maricopa County were at or above 4 pCi/L for 2008 to 2017, against 16.8% across Arizona (2,229 tests) and 36.5% nationally. 0 of Arizona's 15 counties are in Zone 1.
Should I test for radon in Maricopa County?
Yes. EPA recommends testing every home whatever its zone: "This map should not be used to determine if individual homes need to be tested." Fix the home at 4 pCi/L or more and consider a fix between 2 and 4 pCi/L; EPA says there is no known safe level of radon exposure.
More for Maricopa County
- Maricopa County title searchOwner of record, deeds, mortgages and liens from the official Maricopa County records, $49 per report.
- Maricopa property fraud alertThe recording office's own alert service for Maricopa, and free nightly monitoring of a property's official records: new recorded documents, owner changes and tax sale lists.
- Mesa building violations and permitsFree lookup of open violations, condemned or unsafe cases and building permits for any Mesa address. The report adds them to the title search.
- Glendale code compliance casesFree lookup of open code compliance cases, clean-and-lien actions and court cases for any Glendale address. The report adds them to the title search.
- Gilbert building permitsFree lookup of issued, finaled and expired building permits for any Gilbert address, by parcel. The report adds them to the title search.
- Maricopa loan limitsThis year's FHFA conforming, FHA and VA county loan limits for 1 to 4 unit homes, from FHFA's and HUD's official files.
- Maricopa fair market rentHUD Fair Market Rents for studios to 4 bedrooms, the voucher payment standard range and the change from last year.
- Maricopa property tax rateEffective property tax rate from Census survey data: median taxes paid against median home value, ranked in the state.
- Environmental records reportSuperfund, hazardous waste, leaking tank and brownfield sites near any Maricopa address, with distances and a site map. A records search, not a Phase I.
- Superfund sites in ArizonaEvery EPA Superfund site in Arizona with its status, county and a map, refreshed nightly from federal records.
- USDA eligibility map: ArizonaHow much of each Arizona county is in a USDA-eligible rural area, the towns mapped ineligible, and a free address check.
- Opportunity zones in ArizonaEvery designated Opportunity Zone tract in Arizona by county, from the IRS list, and the tracts eligible for the 2027 round.
- Census tract lookupThe census tract of any Maricopa address with its FFIEC income level and HUD Qualified Census Tract and DDA status.
Other free hazard lookups
- Fault lines near an addressUSGS-mapped earthquake faults within 5 miles, their age and slip rate, and the USGS seismic hazard value.
- Power lines near an addressHigh-voltage transmission lines within 1 mile from federal maps, with voltage and distance.
- Flood zone lookupThe FEMA flood zone mapped at any US address. Not an official flood zone determination.
- Superfund sites near an addressThe nearest EPA Superfund (NPL) sites and their status.
All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).
Radon in every Arizona county · Radon map of every state
Data compiled 2026-10-20. County FIPS 04013. County-level screening information, not a radon measurement of any building.