Radon is a naturally-occurring gas produced by the radioactive decay of the element radium. Radon itself is radioactive because it also decays to form the element polonium. Polonium is also radioactive - it is this element, which is produced by radon in the air and in people's lungs, that can hurt lung tissue and cause lung cancer. Radon is ubiquitous (usually in small amounts) in rock and soil and can be carried in water, air, and in natural gas. Some rock types have the potential to produce higher-than-average amounts of radon gas. (USGS.gov)
The following are statements from the EPA. For more information please visit EPA.gov
Lung cancer kills thousands of Americans every year. Smoking, radon, and secondhand smoke are the leading causes of lung cancer.
Smoking is the leading cause of lung cancer. Smoking causes an estimated 160,000* cancer deaths in the U.S. every year (American Cancer Society, 2004).
Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked.
Secondhand smoke is the third leading cause of lung cancer and responsible for an estimated 3,000 lung cancer deaths every year.
Radon levels are measured in picocuries per liter, or pCi/L. Levels of 4 pCi/L or higher are considered hazardous. Radon levels less than 4 pCi/L still pose a risk and in many cases can be reduced, although it is difficult to reduce levels below 2 pCi/L.
The most common mitigation strategy involves soil depressurization which works by reversing the air pressure relationship between indoors and the soil reducing concentration in the soil adjacent to the indoors.
Types: Active soil depressurization (a fan is used to depressurize). And passive soil depressurization (a soil gas retarder between the gas permeable layer and slab or over exposed soils in the crawlspace.
Types of ASD: A slab on grade would use a sub slab depressurization system and a crawlspace would use a submembrane depressurization. ( please refer to our crawlspace liner system tab for this system).
Basement and Slab-on-Grade Homes In homes that have a basement or a slab-on-grade foundation, radon is usually reduced by one of four types of soil suction: subslab suction, drain-tile suction, sump-hole suction, or block-wall suction. Active subslab suction - also called subslab depressurization - is the most common and usually the most reliable radon reduction method. One or more suction pipes are inserted through the floor slab into the crushed rock or soil underneath. They also may be inserted below the concrete slab from outside the home. The number and location of suction pipes that are needed depends on how easily air can move in the crushed rock or soil under the slab and on the strength of the radon source. Often, only a single suction point is needed.
Crawlspace-Homes. An effective method to reduce radon levels in crawlspace homes involves covering the earth floor with a high-density plastic sheet. A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called submembrane suction, and when properly applied is the most effective way to reduce radon levels in crawlspace homes.
Another less-favorable option is active crawlspace depressurization, which involves drawing air directly from the crawlspace using a fan. This technique generally does not work as well as submembrane suction and requires special attention to combustion appliance back-drafting and sealing the crawlspace from other portions of the home. It also may result in increased energy costs due to loss of conditioned air from the home. In some cases, radon levels can be lowered by ventilating the crawlspace passively, or actively, with the use of a fan. Crawlspace ventilation may lower indoor radon levels both by reducing the home's suction on the soil and by diluting the radon beneath the home. Passive ventilation in a crawlspace is