All 30 guides, grouped by topic. Start with the section that fits where you are, from understanding radon to testing, fixing it, and handling a home sale.
What radon is, how it gets into a home, whether it is actually dangerous, and how worried you should really be. See all →
Basements collect more radon than any other part of a home because they sit closest to the soil source and ventilate the least, making testing essential.
Read the guide →The EPA's radon zone map shows which US counties and states face the highest average indoor radon levels, and why your specific home can still surprise you.
Read the guide →Radon levels are shaped by soil geology, foundation type, and indoor pressure. Here is what pushes levels high and why two neighboring homes can read so differently.
Read the guide →Iowa, North Dakota, Pennsylvania, and a cluster of Midwest states top every radon survey. Here is what the EPA data shows and what to do about it.
Read the guide →The U.S. EPA sets the 4 pCi/L action level that all 50 states follow, but average radon concentrations and state programs vary considerably by region.
Read the guide →The EPA's 4 pCi/L action level is not a safety cutoff. Here is what the number actually means, how it was set, and what to do if your home exceeds it.
Read the guide →pCi/L is the unit US labs use for indoor radon. Learn what it means, why the EPA set 4 pCi/L as the action level, and how it compares with Bq/m3 standards worldwide.
Read the guide →A plain-language look at the EPA's 4 pCi/L action level, the U.S. home average of 1.3 pCi/L, and how to put your own test result in context.
Read the guide →The EPA sets an action level at 4 pCi/L, but no radon level is free of risk, and US homeowners need to understand what any test result actually means.
Read the guide →The EPA acts at 4 pCi/L, but radon risk is a gradient with no safe threshold. Here is what different readings mean and what US homeowners should do.
Read the guide →Radon is a natural radioactive gas that seeps into homes from soil. Learn what it is, how it gets in, and why the EPA calls it a real lung cancer risk.
Read the guide →How to test, short-term vs long-term kits, what a good test costs, and how to read your result against the EPA and WHO levels. See all →
A plain-English breakdown of what radon test kits actually cost, from free state programs to charcoal canisters, alpha-track kits, and professional testing.
Read the guide →Step-by-step instructions for using a short-term charcoal radon test kit correctly, from closed-house conditions to mailing the sample to the lab.
Read the guide →Why new construction homes aren't automatically radon-free, when to test, and what to do if your RRNC-equipped home still reads above 4 pCi/L.
Read the guide →Charcoal canisters are the most common way to screen a home for radon: here is how they work, what they can and cannot tell you, and where to get one.
Read the guide →Charcoal canisters, alpha track film, and electronic monitors all measure radon differently. Here is how each type works and when to use one.
Read the guide →Step-by-step instructions for testing your basement for radon, including which test to choose, where to place it, and what to do with the results.
Read the guide →How to choose between continuous radon monitors and passive test kits, which devices work best, and what your readings actually mean.
Read the guide →Find out where US homeowners can get free or nearly free radon test kits, from state health department programs to January promotions and what to do when free kits run out.
Read the guide →EPA guidance on radon detector placement: which floor, which room, how high off the floor, and which spots to avoid so your test gives you an accurate reading.
Read the guide →Everything a US homeowner needs to buy, place, and mail back a DIY radon test kit, then read the results and know what action the EPA recommends.
Read the guide →If your home uses a private well, dissolved radon in the water can release into indoor air during showers and dishwashing. Here is how to test and what to do about it.
Read the guide →The EPA links radon to about 21,000 lung cancer deaths a year, and the only way to know your home's level is to test it.
Read the guide →An independent buyer's guide to radon test kits in 2026: free state kits first, then the best short-term, long-term, and digital monitor picks.
Read the guide →Learn exactly what your radon test results mean, when the EPA says you need to act, and what steps to take based on your specific reading.
Read the guide →A step by step guide to testing your home for radon: short-term kits, long-term tests, digital monitors, correct placement, and how to read your result.
Read the guide →Learn when to use a charcoal test kit versus an electronic radon monitor, and which type works for initial testing, home sales, or post-mitigation checks.
Read the guide →Learn which radon test fits your situation, how each type works, and what the EPA's two-test guidance actually means for your home.
Read the guide →How a sub-slab depressurization system actually works, what mitigation costs, and where DIY makes sense versus hiring a pro. See all →
Radon in real estate: testing during a sale, whether to buy a house that already has a system, and who pays for the fix. See all →