I started Radon by County because public radon test results are scattered across state agencies and federal data portals, which makes it hard for homeowners to see what tests in their own county have found. This site brings those results together, with the source and time period shown for each figure.
I have over 15 years of experience working with data-driven websites, and I'm a project manager in the wireless industry. Health awareness in that industry led me to the same awareness about our homes.
I edit every guide and fact-check it against its sources before it's published, and we cite only primary sources such as government agencies, the World Health Organization, universities and peer-reviewed research. County figures come directly from the published data and are spot-checked against it. When we find an error, we fix it, and a corrected guide gets a new "last reviewed" date.
I'm not a certified radon professional, and nothing on this site replaces a test of your own home. For testing or fixing a home, I recommend contacting your state radon program or a certified radon professional.
Guides by Ray Roman
- How radon mitigation systems work How a radon mitigation (venting) system pulls radon from under your home, the main types by foundation, installation rules to check, and upkeep.
- How to test for radon Short-term and long-term radon tests, where to place a kit, how to read the result, and what changes when you are buying or selling a home.
- Radon exposure symptoms and poisoning Radon causes no immediate symptoms. What long-term exposure can lead to, the lung cancer warning signs, who is most at risk, and what to do next.
- Radon inspections: what happens and who does them What a radon inspection is, how the test is done during a home sale, who is qualified to do it, and what buyers and sellers should ask for.
- Radon levels explained What radon numbers mean, EPA's 4 pCi/L action level, the WHO reference level, converting pCi/L to Bq/m³, and the lifetime lung cancer risk at each level.
- Radon mitigation system installation: steps, DIY vs pro What happens when a radon mitigation system is installed, step by step, which states require a licensed installer, and what to know before doing it yourself.
- What is radon? Radon is a radioactive gas you can't see, smell or taste. What it is, where it comes from, how it gets into homes, what levels are normal, and why it matters.
- Radon fans: how they work What a radon fan does, where it has to go, how much power it uses, how long it lasts, and how to tell from the gauge that it's working.
- Where to buy a radon test kit Where to get a radon test kit, from home improvement stores and online to discounted and free state kits, and what to check before you buy one.
- Radon fan noise, lifespan and replacement How to tell a radon fan is failing, what fan noise and condensation mean, how long fans last, and what happens when one is replaced.
- Radon testing and inspection cost What a radon test costs, from free state kits and $10 to $50 home kits to $50 to $200 for a professional, what changes the price, and which test is worth paying for.
- Radon fan replacement and installation cost What it costs to replace a radon fan, what a new system costs, and what a radon fan costs to run each year, from state radon programs and federal data.
- Radon in basements Why radon is usually highest in basements, whether a basement has its own safe level, when to test yours, what a high result means upstairs, and how to fix it.
- Sealing cracks for radon: what works Does sealing basement cracks lower radon? What EPA says about sealing alone, which sealants the standards call for, and where sealing does help.
- Radon sump pump covers Why an open sump lets radon in, what a radon sump cover must do under EPA's standards, and how a sealed sump becomes part of a mitigation system.
- Radon-resistant new construction and passive radon systems How radon-resistant features work in a new home, what a passive radon system costs and does, when to add a fan, and what to ask your builder.