Radon is a naturally occurring radioactive gas that is invisible, odorless, and tasteless. It originates from the natural decay of uranium found in nearly all soils and rocks. Radon exposure does not cause immediate or noticeable symptoms upon inhalation. Instead, its health effects accumulate over many years, primarily increasing the risk of lung cancer.
Understanding Radon and Its Exposure
Radon gas forms continuously from the radioactive breakdown of uranium in the Earth’s crust. It moves up through the ground and enters homes through various openings. Common entry points include cracks in solid floors, construction joints, gaps around service pipes, and sump pumps. Radon can also enter through well water, though soil gas is the predominant source.
Once inside, radon can become trapped and accumulate to elevated levels due to lower indoor air pressure, creating a vacuum effect. Normal household activities, such as using exhaust fans or clothes dryers, can further contribute to this pressure differential, drawing more radon indoors. While some building materials like granite can emit small amounts of radon, the primary concern for indoor radon levels stems from its movement from the soil beneath structures. The danger arises from inhaling the radioactive decay products of radon, which are solid particles that attach to dust and aerosols. These particles, not the gas itself, pose a risk when inhaled and trapped in the lungs.
Health Risks of Long-Term Exposure
Prolonged exposure to radon leads to serious health consequences, most notably lung cancer. When radon decay products are inhaled, they deposit on the cells lining the airways within the lungs. These radioactive particles emit alpha radiation, which can damage the DNA within lung cells. This cellular and genetic damage can accumulate over years, eventually leading to the development of cancerous cells.
Radon is considered the second leading cause of lung cancer overall, and it is the primary cause among non-smokers. Estimates suggest that radon contributes to approximately 21,000 lung cancer deaths annually in the United States, with about 2,900 of these occurring in individuals who have never smoked. The risk is significantly amplified for smokers, as the combined exposure to radon and cigarette smoke creates a much higher likelihood of developing lung cancer than either factor alone. Symptoms associated with radon exposure are signs of the resulting lung cancer, which can include a persistent cough, shortness of breath, chest pain, wheezing, or even coughing up blood. These symptoms typically do not appear until the cancer has progressed to a more advanced stage, often decades after initial exposure.
Testing and Mitigation
Since radon is undetectable by human senses and causes no acute symptoms, testing is the only reliable way to determine indoor radon levels. Home radon testing kits are widely available and can provide an initial assessment. These kits often utilize charcoal canisters or alpha track detectors and can be used for short-term measurements, typically spanning a few days to a week, or for long-term measurements over several months to a year. Long-term tests are generally more accurate as they account for fluctuations in radon levels due to seasonal changes and weather conditions. Professional testing services are also available and recommended for a more comprehensive evaluation, particularly during real estate transactions.
If elevated radon levels are detected, mitigation strategies can effectively reduce the concentration within a home. A common and highly effective method is active soil depressurization (ASD), also known as sub-slab depressurization. This system involves installing a vent pipe and a fan that draws radon gas from beneath the foundation and exhausts it safely outside the building. Sealing cracks and other entry points in the foundation is another important step, as it limits radon entry and enhances the effectiveness of other mitigation techniques. These systems can reduce indoor radon levels by up to 99 percent, significantly lowering the long-term health risks associated with exposure.