Common Questions About Radon

| OSHA, USF Safety Florida

USF SafetyFlorida Consultant Neil Gunter answers some commonly asked questions about Radon.

We’re accustomed to dealing with the occupational hazards we can see, hear, feel, or smell. But radon is detectable only by testing, and it’s present in some amounts almost everywhere. This naturally occurring gas has been found in every state, including Florida, and becomes hazardous to our health when concentrated. The following are common questions and answers about radon gas.  

What is radon?

Radon is a colorless, odorless, tasteless, invisible, and chemically inert gas that comes from the decay of radium in the soil. Radium is a decay product of uranium. Some level of uranium is present in almost all rocks and soil derived from rocks. Over time, radon gas leaves the soil and becomes part of the air and water. It can be in the air around you, but it’s usually in tiny amounts that aren’t harmful.

What is the health risk associated with radon?

Radon is the second leading cause of lung cancer behind smoking. If you are exposed to high levels of radon, and you smoke, your chance of getting lung cancer is much higher. The health effects of radon are generally associated with many years of exposure to high levels, usually in your home or workplace. 

When you breathe in radon, it gets into the lining of your lungs and gives off radiation. Over a long time, that can damage the cells and lead to lung cancer. About 21,000 people die each year from lung cancer related to radon. No routine medical tests can tell you if you’ve breathed in too much radon. And no treatments will clear it from your body.

Radon poisoning doesn’t show up right away. It can take anywhere from 5 to 25 years for health problems to show up

What causes Radon to concentrate in some buildings?

Radon is a very low-level radioactive material with a short half-life of 3.8 days. Half of the dangerous atoms decay into a more stable form in 3.8 days and half of the remainder in another 3.8 days, and so on. The soil in an area will emit radon at a constant rate, so any radon seeping into a building is constantly resupplied. The process results in a level of radon in a facility that doesn’t change much without intervention. The indoor level may vary some with seasonal changes depending on factors like whether you open windows, but the entry rate remains constant. Radon exposure comes from being indoors in homes, offices, schools, and other buildings. The levels of radon in homes and other buildings can vary locally depending on the nature of the rock and soil in the area. The level can be different even within neighborhoods. Elevated radon levels have been found in parts of every state. Radon gas given off by soil or rock accumulates in crawl spaces or under building slabs and enters the buildings through cracks in floors or walls; construction joints; or gaps in foundations around pipes, wires, or pumps. Higher radon levels will be found in a building’s lowest area. Small amounts of radon can sometimes be released from the water supply into the air. It can be inhaled as the radon moves from the water to the air. Water that comes from deep, underground wells in rock may have higher levels of radon. Radon has been detected in a few Florida wells but not in treated city water supplies. 

I live in Florida, should I be concerned? 

In Florida, one in five homes tested has elevated radon levels above the action level of 4 pCi/L. Elevated radon levels have been found in all types of buildings, including manufactured homes, schools and high-rise condominiums. Elevated levels of radon can be detected in any part of Florida; however, nine counties are known to have a higher radon level on average than the remainder of the state. These counties are Columbia, Union, Alachua, Marion, Citrus, Leon, Hillsborough, Polk and Dade. Homes and buildings near phosphate deposits should always be tested. Don’t assume a recently built building or home is free of radon. There are very specific measures needed for new construction to prevent radon intrusion. The measures aren’t all common to typical construction. The picture below shows average background radon levels across the United States.

How do I test for radon?

A home or building owner can either hire a professional to test for radon or buy a test kit and perform the test themselves. Test kits and be obtained for under $50 with lab fees included. Testing involves using either short-term or long-term test kits. The short-term tests take from a couple of days up to 90 days and are often used when a quick result is needed, such as for a real estate transaction. The more accurate long-term tests take from 90 days to around a year. The test kits include instructions for mailing in the kit for laboratory analysis. More expensive digital radon monitors are available. An issue with constant readout digital monitors is that they cannot be calibrated by homeowners. One factor to consider when deciding how to test is that the soil emits radon very consistently over a person’s lifetime. The level won’t vary. This is due to the nature of the radioactive particle decay. If low or high levels are detected, the levels the soil emit remain the same year after year. 

I tested for radon and my building is over 4 pCi/L. What should I do?

The object of radon mitigation is preventing radon infiltration into the building and removing the radon from the building when all the infiltration cannot be prevented. Radon mitigation efforts typically include both. You cannot reasonably affect the amount of radon emitted from the soil, but you can stop the radon gas from entering and/or accumulating in the building. Some buildings or homeowners will take on the project themselves. There are also professionals available who can handle the entire process, from testing through mitigation. 

Mitigation can sometimes be straightforward, involving sealing entry points such as cracks or pipe penetrations or/and providing ventilation for a crawl space. In these cases, some homeowners may decide to take on the project themselves. Some mitigation methods involve more complicated measures, like venting radon gas from under a concrete slab. Few homeowners are likely to take on this type of project. Whichever route you take, retesting should be done following mitigation. 

Getting Started

Radon is a risk that shouldn’t be ignored. The testing is simple, and the cost of a do-it-yourself test is insignificant.  If you haven’t tested it, put it on your priority list of to-do items. 

If you need assistance and recommendations on improving your safety management systems and your role in the process, submit a request for a FREE consultation from USF SafetyFlorida at

By Neil Gunter

Safety Consultant-USF SafetyFlorida Consultation Program