Below is some information based on data that was aggregated from over 400k radon tests and analyzed by the University of Toledo's engineering department.
The average home in Lorain County tested at 4.8 pC/l which is above the threshold where the EPA recommends taking action. Close to half of the homes tested were above the EPA recommend action level.
The average home in Cuyahoga County falls just below the EPA's threshold for taking action. The average home in Cuyahoga county tested at a 3.0 pC/l. Roughly 1 out of 5 homes tested above the EPA's action level. This means there are likely over 100,000 homes in Cuyahoga County alone that have unsafe Radon levels!
The average home in Medina county tested at 4.2 pC/l which is above the EPA action level. Close to half of the homes tested in Medina County were above the level where a Radon Mitigation system is recommended.
The average home in Summit County tested at a 5.2 pC/l which is above the EPA action level. Greater than 1/3 of the homes tested were above the level where a Radon mitigation system is needed.
The University of Toledo's engineering department has a complete list of radon statistics by zip code available here: