Radon Frequently Asked Questions

Radon is constantly being generated by the radium in rocks, soil, water and materials derived from rocks and soils. The radon generated in rocks or water usually stays trapped in that material unless the rocks are fractured or the water is mixed with the air. Radon-222 is the decay product of radium-226.

Radon-222 and its parent, radium-226, are part of the long decay chain for uranium-238. Since uranium is essentially everywhere in the earth’s crust, radium-226 and radon-222 are present in almost all rock and all soil types.

The amount of radon soil can produce depends on local geology and can vary from house to house. Radon levels in the soil range from a few hundred to several thousand pCi/L (picoCuries per Liter). The amount of radon that escapes from the soil to enter the house depends on the suction created within the house, soil porosity, soil moisture, and weather.

Based on a national residential radon survey completed in 1991, the average indoor radon level in the U.S. is about 1.3 picoCuries per liter (pCi/L). The average outdoor level is about 0.4 pCi/L.

PicoCuries per liter (pCi/L) is a unit for measuring radioactive concentrations. The curie (Ci) unit is the activity of 1 gram of pure radium-226. Pico is a scientific notation denoting a factor of 10^-12.

One pCi is one trillionth of a Curie, 0.037 disintegrations per second, or 2.22 disintegrations per minute. At 4 pCi/L (picoCuries per liter, the EPA’s recommended action level), there will be approximately 12,672 radioactive disintegration events in one liter of air during a 24-hour period.

EPA recommended 4 pCi/L the recommended action level for radon in 1986 for several reasons:

• At lower levels (< 2 pCi/L) measurement devices’ false negative errors increased threefold, and false positive errors increased twofold
• Mitigation research indicates that elevated levels can be reduced to less than 4 pCi/L 95% of the time
• Research shows that 2 pCi/L can be achieved 70% of the time
• Today’s mitigation technology can reduce radon levels to between 2-4 pCi/L most of the time

Cost benefit analysis performed in 1986 indicate that an action level of 4 pCi/L results in a cost of about $700,000 per lung cancer death saved. If the action level was set at 3 pCi/L, the cost would be $1.7 million, and if set at 2 pCi/L, the cost would be $2.4 million per lung cancer death saved.

EPA states that 4 pCi/L is a recommended action level, yet homeowners can further reduce their potential lung cancer risk by mitigating homes that are below 4 pCi/L.

real estate transactions 

Follow mitigation guidance as outlined in the US EPA Homebuyers and Sellers Guide to Radon.

short term test

If your results are below 4 pCi/L, continue testing your home every 2 years.

If your results were twice the 4 pCi/L EPA action level or greater, it is suggested that you perform another radon test in the same area and for the same duration, and then average the results of the 2 tests.

• If the average of these two tests is below 4 pCi/L, retest your home every 2 years
• If the average is above 4 pCi/L, consult with a certified mitigator regarding your next step

If the result is above 4 pCi/l but less than 8 pCi/l, choose between either a short term or a long term follow-up test. A long term test would be preferred. A long term test lasts over 91 days and provides a better representation of the long term average radon concentration in your home. It takes into account variations in radon concentration that naturally occur over time.

• If the follow up test result is over 4 pCi/L, consult with a certified mitigator regarding your next step

Long term test

• If the result is less than 4 pCi/L, continue testing your home every 2 years
• If the result is greater than 4 pCi/L, it is suggested that you perform another short term test in the same area and average the results
• If the results of both tests or the average of both tests are greater than 4 pCi/L, consult with a certified mitigator regarding your next step

About 1 in 5 radon tests made in Florida are found to be elevated. Locally the number of homes reporting elevated radon varies from a high of 7 out of 10 to a low of 1 out of 100.

Elevated radon levels have been reported from all regions of the state. Ultimately the only way to tell if your home has a radon problem is to test for it.  

Radon does decay (break-down); however, the ability for any given patch of land to produce a radon problem in a building placed on it is effectively constant during your life time.

Radon 222 is a radioactive element in the Uranium 238 decay chain. The ‘parent’ element to radon is Radium 236. While radon has a half-life of 3.8 days and thus decays out rather quickly, Radium 226 has a half-life of 1620 years. Any radon in the ground is continually being replenished by the decay of the radium in the soil.

With a half life of 1,620 years, the amount of radium and the rate of radon production during an individual’s life, or the design life expectancy of your average building, is effectively constant. Radon is constantly generated and available to enter and accumulate in buildings at high concentrations.

There are no immediate symptoms associated with radon. However, chronic exposure to elevated radon levels has been demonstrated to cause an increased incidence of lung cancer in humans.

Radon is the leading cause of lung cancer among non-smokers. Major scientific organizations continue to estimate that approximately 12% of lung cancers annually in the U.S. are attributable to radon. When radon and its decay products are inhaled into your lungs, they emit particles full of energy called alpha particles. These alpha particles can strike the sensitive lining of the lungs (bronchi). When this happens, the cells and their DNA in your lungs are damaged, increasing your risk of developing lung cancer. Most of the alpha particle radiation comes from radon decay products.

Lung cancer is the only health effect which has been definitively linked with radon exposure. Lung cancer usually occurs after prolonged exposure (10-25 years). Smokers are at higher risk of developing radon-induced lung cancer, so prevention is the best defense. People should not smoke and also reduce the amount of radon they breathe.

Most indoor radon comes into the building from the soil or rock beneath it. Radon and other gases rise through the soil and get trapped under the building. The trapped gases build up under the house. Air pressure inside homes is usually lower than the pressure in the soil. The home acts as a vacuum cleaner suctioning radon and other gases from under the building, forcing gases through floors and walls and into the building. Most of the gas moves through cracks and other openings.

Once inside, the radon can become trapped and concentrated. Openings, which commonly allow easy flow of the gases in, include the following: cracks in floors and walls; gaps in suspended floors; openings around sump pumps and drains; cavities in walls; joints in construction materials; gaps around utility penetrations (pipes and wires); and crawl spaces that open directly into the building.

For most Florida structures, building materials contribute less radon to the indoor air than the outdoor air ambient radon level does. More recent developments in housing construction has created radon problems due solely to radon released from building materials. Residences built entirely of concrete and with fresh air entry less than a two thirds the recommended amount for healthy indoor air, have been found to have building material related radon problems. Because of this phenomenon, Floridians have found elevated radon levels through all floors of high rise multi-family buildings.

Radon may also be dissolved in water, particularly well water. Radon gets released as it aerates inside the house (in the shower, faucets, washing machines). However, the water needs to have at least 10,000 picoCuries per liter to generate 1 pCi/l in the air. The more radon there is in the water, the more it can contribute to the indoor radon level.

While radon problems may be more common in some geographic areas, any home may have an elevated radon level. New and old homes, well-sealed and drafty homes, and homes with or without basements can have a problem.

Florida certified radon measurement businesses can test your home for radon.  Homeowners may also test their house using over-the-counter radon proficient devices available at local home improvement stores or through the internet. The kits are simple to use and are relatively inexpensive (around $20 for short term tests and around $50 for long term tests). To purchase a do-it-yourself kit, check with your local home improvement hardware store or discount department store.

Reliable radon test kits are listed with the National Radon Proficiency Program or the National Radon Safety Board. Additionally, any test kit purchased and deployed needs to be returned to the laboratory for analysis.

Another option is to hire a state certified radon testing company. Anyone offering professional radon services must have a Florida Department of Health Radon Certification. See a complete list of radon measurement businesses by county 

Every person hired to test or fix radon problems must be certified by the Florida Department of Health. It is possible that the person may be a new specialist who has not been added to our website, so please ask us and we will be glad to check our database.

Please report any violations to 800-543-8279.

Yes. The only way to know for sure if you have a radon problem, and to protect your family from radon, is to test your home.

The EPA has broken the state down into three zones according to their potential for high indoor radon levels, with zone 1 having the highest radon potential. Homes in zones 1 and 2 have a statistically higher chance of having elevated levels of radon. However, elevated levels of radon have been found in homes in many counties designated as low radon potentials (zone 3).

Yes. The solution is simple and relatively inexpensive. However, the best solution depends on the size and nature of the radon risk.

If radon levels are low, ventilation and sealing of cracks on the floor may solve the problem. Other situations may require active mitigation systems. The “standard” active mitigation system, that usually involves soil depressurization, costs about $1,200-2,000 installed. Other systems may cost over $3,000.