Michigan Dept. of Environment, Great Lakes, and EnergyEGLE's Michigan Indoor Radon Map was created with data supplied to the state by organization(s) that manufacture and/or analyze short term radon test kits. This tool is intended to help citizens have an understanding of radon concentrations in a given zip code and how indoor radon levels are geologically dependent. It also assists the EGLE radon outreach specialist in identifying areas with low/no testing rates and areas with higher likelihoods of increased indoor radon presence. Data (indoor radon concentration) is collected from organization(s) willing to provide information, which is then filtered to include values associated with first time tests and without active radon mitigation systems. Full analytical data will not be displayed for zip codes with less than 5 test results, only the test kit count will be shown. A zero value indicates insufficient data for analysis and a null value indicates no tests were provided. Statistical analysis has only been done on first time radon tests. It should be noted that in several zip codes total number of tests indicates either first time tests, follow up tests, post repair tests, testing for real estate, or unknown testing. Email radon@michigan.gov for any questions relating to the data. The dataset includes results for approximately the preceding 10 years. Data will be refreshed at a rate no more frequently than monthly, but at least quarterly. A full new dataset will be provided for each transmittal. Download the data behind this map on EGLE's Open Data Portal . View the Web App . Field Name Description ZipCode ZIP Code Number POName Post Office Name MinimumRadonLevel Minimum value of 1sttime tests* MaximumRadonLevel Maximum value of 1sttime tests* TotalTests Count of total number of radon tests done* TotalFirstTimeTests Count of total number of 1sttime radon tests done* AverageRadonLevel Mean value of 1sttime tests * Shown on the Map As: < 2 pCi/L (Retest every 2 -5 years) ≥ 2 - 3.9 pCi/L (Mitigation Suggested) ≥ 4 pCi/L (Mitigation Recommended) MedianRadonLevel Median value of 1sttime tests* TestsGreaterThan2pCi Count of 1sttime tests greater than 2 pCi/L* TestsGreaterThan4pCi Count of 1sttime tests greater than 4 pCi/L* PercentTestsGreaterThan2pCi Number of 1st time tests above 2 pCi/L divided by the total number of 1sttime tests* PercentTestsGreaterThan4pCi Number of 1st time tests above 4 pCi/L divided by the total number of 1sttime tests* LastUpdatedDate Date of last update. Data does not always change with each update. *IMPORTANT NOTE: Full analytical data will not be displayed for zip codes with less than 5 test results, only the test kit count will be shown. A zero value indicates insufficient data for analysis and a null value indicates no tests were provided. Disclaimer: EGLE makes every attempt to ensure data accuracy but cannot guarantee the completeness or accuracy of the information contained within these datasets. The purpose of this map is to assist residents with understanding radon risk potential. This map is not intended to be used to determine if a home in a given area should be tested for radon. Homes with elevated levels of radon have been found in all 83 counties. All homes should be tested regardless of geographic location. ZIP code boundaries do not correspond to legal or administrative boundaries and were originally created for postal delivery purposes. ZIP code boundaries are subject to change over time and are not precise due to the linear nature of postal routes. This dynamic nature makes ZIP codes less reliable for long-term geographical analysis. The USPS does not offer up an authoritative layer for use by mapping professionals. The ZIP code boundaries used in this analysis are sourced from ESRI .ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/7320389d72d241399c04424f62e214a5_1engState of Michigan Open Data PortalPublicMichigan Indoor Radon Results [Michigan]Web servicesMichiganLast Modified: 2025-09-04