Condominium Radon Guide
In Southwest Florida, radon is common in condos from the first floor to a penthouse on the 23rd floor.
The 8 First Things You Need to Know:
- From data collected by the State of Florida, it appears that about 64% of the radon tests conducted in Collier County show radon levels above the USEPA Action Level of 4.0 picoCuries per liter. You can expect to find elevated radon.
- More than likely, the radon origin is the porous concrete blocks that comprise the curtain walls of low, medium and high rise condominiums.
- Emissions of radon gas from these porous concrete blocks enters into the wall cavities and dropped ceiling spaces where it is then free to travel to the air handler which then circulates the radon throughout the breathing zone.
- The optimal cure for the radon thusly emitted and distributed is to seal the inside surface of the concrete blocks to trap the radon inside them until the radon progresses through radioactive decay for about 28 days, after which it is no longer a gas.
- Such sealing could be easily performed during construction and prior to the installation of insulation and drywall on the exterior walls. Gloss paint, mastic or sprayed foam insulation would likely provide good porous concrete block sealing. Once the drywall is installed, such sealing cannot occur unless the drywall and insulation is removed to gain access to the concrete block interior surfaces, an expensive proposition.
- The result of these conditions is that post construction radon mitigation in condos is usually achieved by the addition of outdoor air to dilute and to pressurize the condo dwelling unit. Such a technique is called mechanical ventilation. Mechanical ventilation always presents new and serious risks.
- In southwest Florida, high levels of water vapor exist in outdoor air most of the time. A mechanical ventilation system can deliver heavy loads of moisture into a home when it is running. A poorly designed and poorly tuned radon system can deliver as much as 240 pounds of water a day into a condominium. Many radon systems deliver 40 to 150 pounds of water a day into a condo. Air conditioners can remove some of that moisture if they are cooling 24 hours a day, and seven days a week. But of course air conditioners are rarely cooling in winter and only part time in spring, summer and fall.
- When a condo and its furnishings have soaked up perhaps 5,000 to 7,000 pounds of water, they may reach 70% moisture saturation by weight, at which point mold growth becomes rampant. There are few clues to the occupants that danger of severe mold infestation is approaching until it is too late. It may take four years or more for the mold to appear from radon system operation.
Radon Mitigation Secrets:
- Radon Mitigation by mechanical ventilation can easily cause moisture, mold and odor problems thereby destroying property, reducing fair market value, making property difficult to sell and making occupants complain of illnesses.
- As they grow, many molds create toxins that are used as self defense mechanisms to protect themselves from disturbances. Mold scientists tell us that some such mold-generated toxins, tricothecenes are among the most toxic substances found in nature. A few "experts" tell us that tricothecenes are harmless to humans.