A Radon Test Kit in the Hardware Store Aisle
Say you quit smoking five years ago. You’re at the hardware store buying paint for a basement remodel, and next to the paint chips you spot a small box labeled “radon test kit.” You’ve heard the word before, but you’re not sure it applies to you anymore. You don’t smoke now, so does it matter?
It does. Radon is a separate, unrelated risk factor for lung cancer, and it comes from the ground under your home, not from anything you smoke or used to smoke. If you currently smoke, formerly smoked, or live with someone who does, radon is worth understanding on its own terms. This guide explains what radon is, why testing is the recommended first step, and how to read a test result without treating it as a medical diagnosis.
What Radon Actually Is
Radon is a naturally occurring radioactive gas. It forms when uranium in soil and rock breaks down, and it can seep into homes through cracks in the foundation, gaps around pipes, or a dirt-floor crawlspace. You cannot see it, smell it, or taste it. The only way to know if it’s in your home, and at what level, is to test for it.
Because radon comes from the ground, it can be present in any home — new or old, with or without a basement, in any region of the country. A neighbor’s low reading does not tell you anything reliable about your own house.
Why This Matters More If You Smoke or Have Smoked
According to the U.S. Environmental Protection Agency (EPA) and the U.S. Surgeon General, radon is the second leading cause of lung cancer in the United States, after cigarette smoking. The Centers for Disease Control and Prevention (CDC) cites the EPA and Surgeon General estimate that radon contributes to more than 21,000 lung cancer deaths each year nationally.
The CDC also notes that radon exposure combined with smoking significantly increases lung cancer risk beyond what either factor causes on its own. Quitting smoking and testing your home for radon are two separate, independent actions — neither one substitutes for the other. If you’ve already quit smoking, that was a meaningful step covered in our COPD & Respiratory Wellness section, and testing your home for radon is a second, unrelated step worth taking.
Where This Guide Stops — Read This Before You Continue
This article explains how to test a home for radon and how to interpret the result using EPA guidance. It is not a lung cancer screening tool, and a radon test result — high or low — is not a medical diagnosis of anything. If you have symptoms such as a persistent cough, coughing up blood, unexplained weight loss, chest pain, or shortness of breath that is new or getting worse, contact a doctor promptly rather than waiting on a radon test result. If you are experiencing a medical emergency, call your local emergency services number right away.
This guide also does not recommend, rank, or link to any specific test kit brand, contractor, or mitigation company. It sticks to the process EPA and CDC describe, and where to find vetted professionals through official channels. (See our Editorial Standards for how we handle sourcing and scope decisions like this one.)
Stage One: Decide How You’ll Test
EPA-oriented radon guidance points to two main ways to test a home:
- Do-it-yourself test kits. These are available through some state radon programs (sometimes free or discounted), through retail stores, and through university-affiliated national radon program services that sell discounted kits online. A short-term kit is placed in the lowest lived-in level of the home for a set period and then sent to a lab for analysis.
- A qualified radon measurement professional. This is useful if you’re buying or selling a home, want a more formal reading, or simply prefer not to handle the kit yourself. The EPA notes that states are required to maintain lists of credentialed providers, either through their own state licensing program or through one of two national credentialing bodies: the National Radon Proficiency Program (NRPP) and the National Radon Safety Board (NRSB).
Either path is a reasonable starting point. What matters most is testing at all, since radon levels vary house to house and cannot be estimated by guesswork.
In short, the do-it-yourself process looks like this:
- Get a kit from your state radon program, a retailer, or a university-affiliated radon program service.
- Place it on the lowest level of your home you regularly use, away from drafts and exterior openings.
- Leave it undisturbed for the full period printed on the box.
- Seal it and send it to the lab named on the kit.
- Read your result against the EPA’s 4 pCi/L action level, and decide your next step from there.
Stage Two: Take the Test
If you’re using a DIY kit, follow the instructions printed on the box exactly — placement, closed-house conditions, and mailing timelines affect accuracy. General best practice from radon programs is to place the kit in the lowest level of the home you regularly use (this includes a finished basement, but not a crawlspace you never enter), away from drafts, exterior doors, and windows, and to leave it undisturbed for the full testing period before sealing and mailing it to the lab named on the kit.
If you hire a measurement professional instead, they will place calibrated equipment in your home and provide you with a lab-backed reading and report.
Stage Three: Understand Your Result
The EPA’s recommended action level is 4 picoCuries per liter (pCi/L) of air. If your test result comes back at or above 4 pCi/L, the EPA and CDC recommend taking action to reduce the level. Even below 4 pCi/L, the CDC notes there is no fully “safe” level of radon, and further reducing exposure still provides some benefit — this is a personal risk-tolerance decision, not a strict requirement.
A single test is a snapshot. Radon levels can fluctuate with weather, seasons, and how a home is sealed or ventilated, which is part of why professionals and long-term testing exist as options if you want a more complete picture over time.
Decision Path: What to Do With Your Number
- Result below 4 pCi/L: No EPA-mandated action is required. You may choose to retest periodically, especially after major renovations, foundation work, or changes to your home’s ventilation, since these can change radon levels.
- Result at or above 4 pCi/L: The CDC recommends contacting your state radon office for a referral to a qualified mitigation contractor. Mitigation systems are a technical, licensed trade — this is not a do-it-yourself repair.
- After mitigation work: Retest the home to confirm the level has actually dropped. A mitigation system that isn’t verified with a follow-up test is an unfinished job.
- Buying or selling a home: A radon test is a common part of a real estate transaction; a professional measurement may be preferable to a DIY kit in this situation for documentation purposes.
Finding Your State’s Radon Program
Every state has a radon program or a designated contact, often connected through EPA regional offices and the State and Tribal Indoor Radon Grants (SIRG) program. These offices can direct you to discounted or free test kits, help you find your home’s general radon risk zone, and refer you to credentialed measurement and mitigation professionals. Start at the EPA’s radon program page to find your state’s contact information rather than searching generically, since radon program structure and contact details vary by state.
Questions Worth Bringing to a Professional or Your Doctor
- If I test above 4 pCi/L, what mitigation options are typical for a home like mine, and what does verification testing afterward involve?
- If I’ve smoked in the past and also have an elevated radon reading, is there anything specific I should discuss with my doctor about lung health monitoring?
- Does my state radon program offer free or discounted test kits, and how do I find a credentialed contractor through NRPP or NRSB or my state’s own list?
- How often should I retest, given my home’s age, foundation type, and any renovations?
The Short Version
Radon is an odorless, invisible gas linked to a large share of U.S. lung cancer deaths each year, and its risk compounds with smoking history. You cannot detect it without testing. A do-it-yourself kit or a credentialed professional can both get you a real number. The EPA’s action level is 4 pCi/L. Below that, you have options; at or above it, contacting your state radon program for a qualified mitigation referral is the recommended next step. None of this replaces a conversation with your doctor about your personal lung health, especially if you have current smoking-related symptoms.
To understand how we source and verify information like the facts in this article, see How We Review.
Sources
- U.S. Environmental Protection Agency, “Radon,” epa.gov/radon
- Centers for Disease Control and Prevention, “About Radon,” cdc.gov/radon/about
Educational Disclaimer
This article is for general educational purposes only and is not medical advice, a medical diagnosis, or a substitute for professional radon measurement or mitigation services. SmokersLung.com is an independent educational publication and is not affiliated with the EPA, CDC, any state radon program, or any radon testing or mitigation company. Radon guidance, action levels, and program details can change; always confirm current information directly with the EPA, your state radon program, or a credentialed professional before making decisions about your home. If you have concerns about your lung health, symptoms, or smoking history, talk with a licensed healthcare provider.
By SmokersLung.com Respiratory Health Education Team. Last updated September 10, 2026.