Radon is a radioactive gas that comes from the natural decay of uranium in soil, rock, and water. You cannot see it, smell it, or taste it. It seeps up through the ground and into buildings through cracks in foundations, gaps around pipes, and other openings. Once inside, it can build up to dangerous levels, especially in basements and lower floors. The link between radon and lung cancer is not speculative. The U.S. Environmental Protection Agency estimates that radon causes about 21,000 lung cancer deaths every year in the United States alone, making it the second leading cause of lung cancer after smoking. If you or a family member has been diagnosed with lung cancer after years of living or working in a building with high radon levels, you may be wondering who is legally responsible for the harm. The answer depends on who knew about the radon, who had a duty to protect you, and whether they failed to meet that duty.
The most straightforward claims arise against landlords and property owners. A landlord who rents out a home or apartment has a legal duty to provide a habitable and safe living environment. That duty includes addressing known health hazards. If a landlord has actual knowledge of elevated radon levels and does nothing to fix the problem, they can be held liable for the resulting lung cancer. The challenge is proving knowledge. In many states, a landlord is not automatically required to test for radon unless there is a specific law or regulation. But once the landlord learns of a positive test result, or receives a complaint from a tenant about a musty smell or health concerns, ignorance is no longer an excuse. Failure to act after that point is negligence.
Home sellers face a similar but distinct set of obligations. Many states have real estate disclosure laws that require sellers to disclose known material defects, and radon contamination qualifies. If a seller tested for radon, got a high reading, and then failed to disclose it to the buyer, that seller can be sued for fraud or negligent misrepresentation. The buyer who moves in and later develops lung cancer has a strong claim, although the medical causation link must be established. Even if a seller never tested, some courts have found a duty to disclose if the seller knew that radon problems existed in the neighborhood or if the house had a basement with visible cracks and the seller had reason to suspect radon accumulation. The key is whether the seller acted in good faith or tried to hide a known risk.
Employers also carry liability for radon exposure in the workplace. Workers in underground mines, particularly uranium mines, face the highest risk. But radon can also accumulate in office buildings, schools, and industrial facilities with poor ventilation. An employer that fails to test for radon, fails to install mitigation systems, or ignores high readings can be held responsible for an employee’s lung cancer. Workers’ compensation laws often apply, which means the employee may be limited to compensation through that system rather than a civil lawsuit. However, there are exceptions. If an employer intentionally concealed the radon hazard or acted with reckless disregard for worker safety, a civil suit may be possible in some jurisdictions. Third-party claims can also arise against companies that installed defective radon mitigation systems or that supplied faulty test kits.
The product liability angle hits manufacturers of radon testing devices. These kits are sold to homeowners, landlords, and employers who rely on their accuracy. If a test kit gives a falsely low reading, and people continue living or working in a contaminated building because they trust that result, the manufacturer can be sued for making a defective product. The same applies to mitigation systems that are supposed to reduce radon levels but fail to do so because of poor design or shoddy installation. Proving a product liability claim in a radon context requires showing that the test kit or mitigation system was defective, that the defect caused the user to remain exposed, and that the exposure caused the lung cancer.
Across all these claims, the hardest part is proving causation. Radon exposure is invisible, and the disease it causes, lung cancer, can take years or even decades to appear. Many lung cancer patients are also smokers, which creates an argument that the smoking, not the radon, caused the cancer. This is not an automatic defense. Radon and smoking have a synergistic effect, meaning the combination is far more deadly than either alone. A defendant cannot escape liability simply because the victim smoked. The law in most states allows a plaintiff to recover damages even if there were multiple causes, as long as radon exposure was a substantial contributing factor. But you need expert testimony from an epidemiologist or a radiation oncologist to establish that the level and duration of radon exposure made the cancer more likely than not.
Another practical issue is the statute of limitations. Every state sets a deadline for filing a personal injury claim. In many states, the clock starts running when the injury is discovered, or when it should have been discovered with reasonable diligence. Because lung cancer from radon can take 15 to 25 years to develop, the discovery rule is critical. If you have recently been diagnosed, you may still have time, but you cannot wait. Once you know the diagnosis, you must investigate whether radon was present in your home or workplace and file your claim before the deadline passes. Missing that deadline means losing your right to sue, no matter how strong your evidence is.
Finally, there is the issue of who actually pays. A landlord or small business owner may not have enough insurance to cover a multi-million dollar judgment. Homeowners’ policies typically exclude pollution and radiation claims. Commercial umbrella policies might cover some situations but often have exclusions for nuclear hazards. That leaves the defendant personally responsible, which can lead to bankruptcy if the claim is large. In practice, this means that even winning a radon lawsuit does not guarantee you will collect the full amount. The better approach is to identify all potentially liable parties, including past owners, builders, real estate agents, and manufacturers, and to pursue claims against each one. An experienced toxic tort attorney can help you sort out who has the deepest pockets and the strongest legal exposure.
Radon is a silent hazard that kills thousands of people every year. The law has slowly caught up with the science, recognizing that property owners, sellers, and employers have a duty to protect people from this invisible radiation. If you have been harmed, the path to compensation is difficult but not impossible. You need to prove knowledge, breach of duty, and medical causation. You need to move quickly. And you need to understand that the real fight is not just about building science or medical tests, but about who is accountable for failing to act when they knew or should have known better.
