Radon is a naturally occurring radioactive gas that seeps into homes through foundation cracks and soil, causing an estimated 21,000 lung cancer deaths annually in the United States. The problem is invisible: radon has no color, smell, or taste, which means families can live in homes with radon levels many times above the Environmental Protection Agency (EPA) safety threshold without ever knowing it. Yet testing is straightforward, and mitigation systems can reduce radon levels by 99% or more.

This Earth Day, environmental health experts are reframing what it means to protect the planet. While forests and oceans matter, the environment where most people spend their time is the one inside their own four walls. According to the EPA, Americans spend roughly 90% of their time indoors, which means the air you breathe at home has a far bigger day-to-day impact on your health than outdoor air quality.

Why Is Radon the Second Leading Cause of Lung Cancer?

Radon forms as uranium naturally breaks down in soil beneath homes. It seeps into living spaces through foundation cracks, sump pits, crawl spaces, and even well water. According to the EPA, radon is the second leading cause of lung cancer in the United States and the leading cause among non-smokers. The gas is particularly dangerous because it accumulates silently over time, and there is no way to detect it without professional testing.

The EPA has set an action level of 4.0 picocuries per liter (pCi/L) for indoor radon. This is the concentration at which the agency recommends homeowners take steps to reduce exposure. Many homes exceed this threshold significantly, yet the problem remains invisible to residents.

What Are the Most Common Indoor Environmental Health Threats?

Indoor environmental health refers to the quality of air, water, and surfaces inside buildings and how they affect the people living there. For homeowners, two specific threats stand out because they are the most common, the most dangerous, and the most invisible:

• Radon in indoor air: A naturally occurring radioactive gas that seeps through foundations and causes an estimated 21,000 lung cancer deaths per year in the United States.
• Contaminants in drinking and bathing water: Private wells, which serve more than 43 million Americans according to the Centers for Disease Control and Prevention (CDC), are not regulated by the EPA the way public water systems are, making homeowner testing essential.

Both threats are routine, both are fixable, and both are usually overlooked until someone decides to test.

How to Test Your Home for Radon and Water Contaminants

• Schedule a professional radon test: If you have never tested your home, or if your last test was more than two years ago, a professional assessment can determine whether your radon levels exceed the EPA action level of 4.0 pCi/L.
• Get a certified lab water quality assessment: For homes with private wells, a certified laboratory test provides a baseline measurement for common contaminants including arsenic, uranium, nitrates, radon in water, lead from older plumbing, and bacteria like E. coli.
• Verify technician credentials: Ensure that any radon or water testing professional is certified through the National Radon Proficiency Program or equivalent state licensing, following national protocols.
• Plan for mitigation if needed: If testing reveals elevated radon, a properly designed mitigation system can reduce levels by 99% or more; for water contaminants, targeted treatments such as reverse osmosis, carbon filtration, UV, or arsenic-specific media can bring levels back to safe ranges.

What Water Contaminants Should Homeowners Know About?

Private well owners face unique risks because their water is not subject to EPA regulation. Common contaminants vary by region and include arsenic and uranium in parts of New England and the Mountain West, nitrates in agricultural regions, radon in water in areas with high soil radon, lead from older plumbing regardless of water source, and bacteria like E. coli after flooding or well damage. Many of these contaminants have no taste and no smell, making testing the only reliable way to identify them.

More than 43 million Americans rely on private wells for drinking water, according to the CDC, which means the responsibility for testing falls entirely on the homeowner. A certified lab test gives families a baseline, and if anything is elevated, targeted treatment can bring levels back to safe ranges.

Why Professional Testing Matters More Than DIY Detection

Because radon cannot be detected by human senses, professional testing is the only reliable method to determine whether a home has a problem. A family can live in a home with radon levels many times above the EPA action level and never know without testing. The good news is that testing is straightforward, and mitigation works.

Professional radon contractors use certified laboratories with consistent quality control and technicians certified through the National Radon Proficiency Program or equivalent state licensing. This ensures that testing follows the same national protocols wherever you live, providing accurate and comparable results.

Earth Day is a natural prompt to take action on the environment you can actually control: the one inside your home. For most people, that environment has a far bigger impact on daily health than outdoor air quality. Testing for radon and water contaminants is a practical, measurable step that can protect your family's health for years to come.