Radon Testing in Knox County OhioYou can’t see radon. And you can’t smell it or taste it.  Yet, it could be a problem if it gets in your home. Radon testing by the Ohio Department of Health has indicated some levels of concern for Knox County residents where some homes have tested 50 times more than what is considered safe. In-home testing is the only way to determine the level of radon in your home. The best time to test is during the colder months when the house is closed up due to the weather.

Free test kits are no longer available

however radon test kits can be purchased by clicking here 

For more information, contact Terri Hillier or Kyle Shackle in the Environmental Health division.


What is radon?

Radon is a colorless, odorless radioactive gas that seeps up from the earth. When inhaled, it gives off radioactive particles that can damage the cells that line the lung. Long term exposure to radon can lead to lung cancer. In fact, over 21,000 lung cancer deaths in the US each year are from radon, making it a serious health concern.

Where does radon come from?

Radon comes from the soil. Radon is caused by the natural breakdown (radioactive decay) of materials that contain uranium. Radon can be found in high concentrations in soils and rocks containing uranium, granite, shale, phosphate and pitchblende. As these materials disintegrate, it turns into radioactive gas...radon. As a gas, radon moves up through the soil and into the air you breathe.

Where is your greatest exposure to radon?

While radon is present everywhere, and there is no known, safe level, your greatest exposure is where it can concentrate-indoors and where you spend most time-at home. Your home can have radon whether it be old or new, well-sealed or drafty, and with or without a basement.

Why is radon a common problem in Knox County homes?

High radon exists in every state in the US. Check out a map of Ohio showing radon concentrations. Some factors that further contribute to Ohio’s high radon levels include:

  • Ohio’s geology produces an ongoing supply of radon.
  • Ohio's climate affects how our homes are built and operate.
  • Ohio’s homes have basements that are used as living spaces.

How does radon enter a home?

Radon entering the homeRadon, because it is a gas, is able to move though spaces in the soil or fill material around a home's foundation. Ohio homes tend to operate under a negative pressure - this is especially true in the lowest portions of the home and during the heating season. This negative pressure acts as a vacuum (suction) that pulls soil gases, including radon, into the lower level of the structure. Some causes of home vacuum are:

  • Heated air rising inside the home (stack effect).
  • Wind blowing past a home (downwind draft effect).
  • Air used by fireplaces, wood stoves, and furnaces (vacuum effect).
  • Air vented to the outside by clothes dryers and exhaust fans in bathrooms, kitchens, or attics (vacuum effect).

Radon can enter a home through the floor and walls -- anywhere there is an opening between the home and the soil. Examples of such openings include dirt floor crawl spaces, unsealed sumps, cracks in slab-on-grade floors, utility penetrations, and the tiny pore spaces in concrete block walls. A basement, of course, provides a large surface area that contacts soil material.

What happens after radon gets into the home?

Radon levels are often highest at the entry point-typically in the lower part of a building. As radon gas moves upward, diffusion, natural air movements and mechanical equipment (such as forced-air ventilation system) distribute the radon through the home. Radon gas becomes more diluted in the upper levels of the home because there is more fresh air for it to mix with.

Greater dilution and less house vacuum effect occur when the house is more open to the outdoors, as during the non-heating season. This generally results in lower indoor radon levels in the summer compared to the winter.

Understanding how radon moves through the home environment helps to explain why timing and location are important factors to consider when conducting a radon test.

How can I find out if my home has a radon problem?

The EPA recommends that all homeowners test their homes for radon. A radon test is the only way to find out how much radon is in your home and if you and your family are at risk. Performing a radon test on your own is easy, inexpensive and takes only a few minutes of your time. The results of a properly performed radon test will help determine if you need to take further action to protect yourself from the health risks of radon. Click here to obtain free radon test kit online.

What if my test shows a high level of radon?

If a reading is greater than 10 pCi in the initial short term test, a second test is recommended to properly evaluate the extent of the problem. In most cases the control measures are reasonably inexpensive such as improving air circulation, sealing or cracks in basement floors and walls and venting of sumps. A number of steps can be taken to lower the amount of radon in a home. A quality radon reduction (mitigation) system is often able to reduce the annual average radon level to below 2 pCi/L. Experienced radon mitigation professionals are available and can install appropriate control systems.

Helpful Links

Ohio Department of Health - Indoor Radon Program

Radon Levels in Ohio

Ohio Radon Information System

EPA - Radon


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Public Health - Knox County Health DepartmentPublic Health is about focused community efforts to prevent disease, promote healthy lifestyles and protect the environment. It is what we do with our community partners to ensure conditions that support the health and well- being of our residents.


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