Radon is a naturally occuring gas found in soil and rock and can enter buildings through openings in the foundation floor or walls. Since radon is tasteless, odorless, and colorless, there are no physical signs that will alert a person to the presence of radon in a home. The only way to know whether a home has elevated radon levels is to test with a device specifically designed to detect radon.
Radon is a Class A carcinogen, which means it is known to cause cancer in humans. It is the second leading cause of lung cancer in the United States, resulting in approximately 21,000 lung cancer deaths each year. Only smoking causes more lung cancer deaths.
How can you tell if you have a radon problem?
Any home can potentially have a radon problem, regardless of whether it's in an area with a high radon potential or a low radon potential, whether it's old or new, energy-efficient or drafty, built on a slab or built over a basement or crawlspace.
Highest Potential: Zone 1 counties have a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter)
There are nine Zone 1 counties in Michigan: Branch, Calhoun, Cass, Hillsdale, Jackson, Kalamazoo, Lenawee, St. Joseph, and Washtenaw.
Moderate Potential: Zone 2 counties have a predicted average indoor radon screening level between 2 and 4 pCi/L
Low Potential: Zone 3 counties have a predicted average indoor radon screening level less than 2 pCi/L
How can I ensure radon-resistant construction?
Four Simple Steps:
1. Gas Permeable Layer: Install a layer of clean gravel or aggregate beneath the slab or flooring system to allow soil gases to move freely beneath the home.
2. Impermeable Layer: Cover that layer with a vapor barrier (plastic or polyethylene sheeting) to help prevent radon and other soil gases from entering the home.
3. Vent Pipe: Run a 3-inch or 4-inch PVC pipe from the gas permeable layer up through the roof.
4. Caulking and Sealing: Caulk and seal all openings in the foundation floor or walls, as well as entry points such as the floor/wall joint; sump openings; cracks; space around plumbing, wiring or ductwork; or openings at the top of a hollow block wall.
To achieve guaranteed results, a trained contractor can be hired to install a radon mitigation (reduction) system. Almost any radon level, regardless of how high it is, can be brought down to below 4 pCi/l.
The most common technique used in Michigan is active soil depressurization (ASD). This reduction method involves reducing the pressure under the house so radon isn't being pushed in through openings in the foundation floor or walls.
ASD systems are fairly simple. They start with a PVC pipe that goes down through the foundation floor and runs up and out of the house. A small in-line fan is attached to create negative pressure under the slab and additional piping extends from the top of the fan to above the roofline. This allows the radon to be exhausted to an area where it can be quickly dispersed and diluted by the atmosphere and will not be drawn back into the house through doors, windows, or other openings.
How much can radon mitigation systems cost?
In Michigan, systems generally cost between $750 and $1,500, depending on where you are located in the state and who performs the work.
The systems can usually be installed in a day or less, and a reputable contractor will provide a guarantee that results below 4 pCi/l will be achieved. Often the systems are so successful that they actually achieve results below 2 pCi/l.
Are there laws in the State of Michigan related to radon issues?
The Michigan Department of Environmental Quality does not license or otherwise regulate radon mitigation contractors. There are currently two national organizations offering certification for testers and mitigators: the National Radon Safety Board and the National Environmental Health Association. Lists of certified contractors from these organizations are available on their websites (www.nrsb.org and www.neha.org) or they can be obtained by calling the Michigan Department of Environmental Quality Indoor Radon Program at 1-800-RADON GAS/1-800-723-6642.
("Indoor Radon". Department of Environmental Quality. www.michigan.gov. Accessed 4 August 2009.)