Radon is an invisible, odorless, tasteless, cancer-causing gas that comes from the natural radioactive breakdown of uranium and radium in soil, rock and water. Radon enters buildings through cracks, holes and pipes in the foundation. All buildings contain some radon, but homes are the most concerning since that is where families spend most of their time.

January is National Radon Awareness Month

To help bring awareness about radon during National Radon Awareness Month, JCPH will be giving away (700 short-term) radon test kits for Jefferson County residents only while supplies last. Please submit a radon kit request between now and January 31 to get your free kit. You can also purchase a kit at JCPH for $10 at any time.

Radon in Colorado

Radon is found throughout the U.S. and is particularly prevalent in Colorado. The U.S. Environmental Protection [external link] Link to radon infographic (PDF) Opens in new window Agency (EPA) has ranked Colorado as a Zone 1 area [external link], meaning the average house will exceed the EPA's action level for indoor radon.

Radon is produced as a decay product from uranium and radium. This naturally occurring radioactive gas is found in most soil, rock and ground water. Since radon is a gas, the inert element can easily travel through cracks and pores without being chemically bound or attached to other elements. Voids and porous materials are found under every building, allowing radon easy entry.

Frequently Asked Questions

  • Where can I get a radon test kit? 
    Thank you for your interest in a radon kit through JCPH. Kits are available at the health department for $10 all year long. Please call 303-232-6301 for information about our $10 kits.
  • Where should I put the test kit? 
    The test kit should be placed in the lowest occupied level (typically a basement) and in the normal breathing zone (about 2-6 ft. from the floor) and 3 ft. from windows, doors, vents or anything that allows airflow.
  • How long do I use the test kit? 
    The test kit is a short-term test, about 3-7 days. We recommend having the kit out for about 4 days to allow for mailing time. Depending on the contact info you provide to the lab, the test results should be returned within 8 days. If the test kit is not analyzed within 11 days of opening, no test result can be provided.

If you have not received a result yet or for further information, please contact: Radon Lab, via mail to address 1936 Butler Bridge Rd, Mills River, NC 28759-3892, via fax to (828) 684-8498 or by email.

  1. Entry
  2. EPA Standards
  3. Health Effects
  4. Mitigation
  5. Radon in Schools
  6. Radon in Water
  7. Resources
  8. Testing

Radon Entry

Elevated radon levels depend upon the strength of the radon source, how easily radon is delivered into the structure and, to a lesser degree, the structure's ventilation rates. In most buildings, 95 percent of the radon entering the structure comes from the rock and soil underneath. The radon is pulled into the building by air pressure differentials created by natural and mechanical ventilation. Natural ventilation occurs due to stack effect (hot air rising in the home), wind and temperature differences between inside and outside air. Rain and low barometric pressure can also increase radon entry. Exhaust fans in the home, as well as negative pressure relative to the outdoors caused by heating systems, also increase radon entry.

These factors cause radon levels to vary, both daily and seasonally. The highest levels are expected during the winter, and lower concentrations are expected during the summer because windows and doors are typically open. Well water and building materials may cause radon in homes, but these usually account for less than 5 percent of the radon that enters.