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A local family narrowly escaped death when carbon monoxide gas seeped into their home last year. The gas is invisible and odorless but did trigger an alarm, alerting the mother who woke her daughters and rushed them into the fresh night air. The source of that gas was never determined.
Another gas that is a growing concern is Radon, according to the World Health Organization and Environmental Protection Agency. Radon gas is a problem in nearly 20 percent of the homes in the United States and it took the lives of some 20,000 Americans in 2009, according to the agencies. These startling statistics have prompted the agencies to designate Oct. 17-24 as National Radon Awareness Week.
Los Alamos isn’t known for Radon issues but that doesn’t mean it doesn’t exist here. Fire Marshal Mike Thompson said, “I’m unaware of emergency issues specific to Radon in our area but if people are concerned with the levels in their homes then it would be worth checking into.”
Radon is a naturally occurring, odorless and colorless gas produced by the breakdown of uranium in soil, rock and water. Because radon is a gas, it can enter buildings through openings or cracks in the foundation. The radon gas itself decays into radioactive solids, called radon daughters, according to the EPA. The radon daughters attach to dust particles in the air and can be inhaled. The inhalation of radon daughters has been linked to lung cancer.
Radon has been identified as the second leading cause of lung cancer in the United States, causing between 15,000 and 22,000 lung cancer deaths annually. Homes with elevated radon levels have been found in practically every county in the United States.
WHO and the EPA are urging every home to be tested for radon regardless of where the home is located, the age of the home or foundation type.
The EPA has established that if a home or building is found to have a radon level of 4 pCi/l or higher, action should be taken to reduce it.
Radon’s primary hazard is caused from inhalation of the gas and its highly radioactive heavy metallic decay products (Polonium, Lead and Bismuth), which tend to collect on dust in the air. The problem arises when these elements stick to cells lining the passageways leading into the lungs.
Radon moving through soil pore spaces and rock fractures near the surface of the earth usually escapes into the atmosphere. Where a house is present, however, soil air often flows toward its foundation for three reasons:
• Differences in air pressure between the soil and the house
• Presence of openings in the house’s foundation
• Increases in permeability around the basement
In constructing a house with a basement, a hole is dug, footings are set and coarse gravel is usually laid down as a base for the basement slab. Then, once the basement walls have been built, the gap between the basement walls and the ground outside is filled with material that often is more permeable than the original ground. This filled gap is called a disturbed zone.
Radon moves into the disturbed zone and the gravel bed underneath from the surrounding soil. The backfill material in the disturbed zone is commonly rocks and soil from the foundation site, which also generate and release radon. The amount of radon in the disturbed zone and gravel bed depends on the amount of uranium present in the rock at the site, the type and permeability of soil surrounding the disturbed zone and underneath the gravel bed, and the soil’s moisture content.
The air pressure in the ground around most houses is often greater than the air pressure inside the house. Thus, air tends to move from the disturbed zone and gravel bed into the house through openings in the house’s foundation. All house foundations have openings such as cracks, utility entries, seams between foundation materials and uncovered soil in crawl spaces and basements.
Most houses draw less than one percent of their indoor air from the soil; the remainder comes from outdoor air, which is generally quite low in radon. Houses with low indoor air pressures, poorly sealed foundations and several entry points for soil air, however, may draw as much as 20 percent of their indoor air from the soil. Even if the soil air has only moderate levels of radon, levels inside the house may be very high.
Radon testing is easy, inexpensive and saves lives, according to the EPA. To learn more, visit www.who.int/mediacentre/factsheets/fs291/en/.
Contact Carol A. Clark at firstname.lastname@example.org