Radon is making frequent headlines these days, raising awareness of the danger it poses and sprinkling radon facts into the news. Through these stories, many people now know radon causes cancer. They are probably aware radon gas seeps into homes and buildings through foundations, cracks, and holes, from the rock and soil beneath foundations. They probably also know it is important to test indoor air concentrations because they can’t see, smell, or taste the presence of this dangerous gas. There are also a few interesting things they may not know. Here are some surprising facts about radon.
When we think of gas, we think of light, airy, stuff that permeates a room as it dissipates, often with its own distinctive smell. Not radon. Looking at the periodic table of chemical elements which lists them according to atomic weight, Hydrogen atoms are the lightweights with a weight of 1. Helium, not much heavier, is next with an atomic weight of 2. Carbon weighs 6, and Gold weighs 79. Radon tips the scale with an atomic weight of 86. FYI, that’s even heavier than lead on an atom-per-atom basis.
Quite dense as far as gases go, radon tends to lay low inside buildings depositing the heaviest concentrations at the lowest levels of a structure, like basements and ground level rooms. Concentrations in first floor spaces are usually less than those in basements by a factor of two, making upper floors less dangerous. Air pressure, circulation, temperature, humidity all make a difference in how the gas behaves inside a closed structure.
Radon is a radioactive element with a half-life of 3.8 days. That’s a relatively short time in the middle of the decay chain transforming highly reactive Uranium into a comparatively stable form of lead. The Uranium 238 isotope goes through a couple of steps to produce Radium, which then decays into radon gas. Radon further transforms, producing generations of dangerous “daughter” products.
Radon’s first generation daughters, Polonium and Bismuth, send out harmful radioactivity. As the atoms emit harmful radiation in the form of alpha and beta particles, they become smaller and lighter, drawn into the lung’s smallest spaces with each breath. The decay chain continues until the atoms are reduced to lead. That takes a while. Uranium-238 has a half-life of 4.5 billion years, and Radium? A mere 1,600 years.
Radon exposure most often comes from gas escaping out of rock and soil beneath the foundation of a building, but it can also be carried in water. Exposure to radon from underground water sources poses a much lower risk than airborne radon.
Radon is measured in units called picocuries per liter, pCi/L, in the U.S. For every 10,000 pCi/L of radon in a water supply, the indoor air concentration is increased by 1 pCi/L. Outdoor radon exposure allows the concentration to dissipate into the atmosphere where it becomes less of a concern.
Wells and springs, particularly in areas with large or multiple underground deposits of granite or limestone, can harbor dangerous levels of radon gas. Wells should be tested every three to five years, especially if the water is used for drinking, cooking, washing or other purposes that put people and water in contact.
On a completely different tack, there are controversial treatments that prescribe visits to radium springs, spas, and baths as a treatment for arthritis. About 75,000 patients took to the waters in Germany, Austria, and in the state of Montana in the U.S. recently, using the low dose radon soaking treatment to alleviate symptoms. Russia has about 100,000 fans of the alternative treatment. Those considering a dip in one of these locations may want to rethink the plan in light of more recent research on radon gas inhalation.
While radon occurs naturally in just about every location on the planet, certain regions are known for dangerously high levels due to geography and geology. It is good to remember that radon concentrations vary widely, not just from country to country and city to city, but also house to house, even within a single lot. It is not unusual to find hot spots dotting a single homesite.
Structures built on top of fissures in granite might deliver radium numbers greater than that of a uranium mine. Deep fissures in rocks allow gas to travel freely into open spaces, directing large concentrations into small areas and up into indoor environments, posing a risk to all who breathe the air.
Studies are ongoing as scientists discover more of radon’s secrets every day. Understanding the decay chain has prompted its use as a marker in ocean and undersea research. Some interesting features have been discovered as well, knowing that gas boils at -78° F, and freezes at -95° F, turning from yellow to brilliant orange as the temperature dips. That makes it useful in laboratories in separation tasks.
The only failure here is in not testing. It’s a win-win situation. If you test and find your levels are acceptable, you’re rewarded with the knowledge that your family is safe. If you test and find your levels need attention, you’re rewarded by knowing you’re doing all you can to reduce the risk of disease caused by radon. And, regardless of the test results, Isn’t it great to know that you cannot fail?
Radon update: facts concerning environmental radon: levels, mitigation strategies, dosimetry, effects and guidelines. SNM Committee on Radiobiological Effects of Ionizing Radiation. http://jnm.snmjournals.org/content/35/2/368.long
5 Interesting facts about radon. Asia Pacific Economics Blog. http://apecsec.org/5-interesting-facts-about-radon/
The Therapeutic use of Radon: A Biomedical Treatment in Europe; An “Alternative” Remedy in the United States. Barbara E. Erickson, PhD. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2477705/
Radon in Your Home: An Overview for New Hampshire Homeowners. Environmental Fact Sheet, New Hampshire Department of Environmental Services. http://des.nh.gov/organization/commissioner/pip/factsheets/dwgb/documents/dwgb-3-12.pdf
The Radioactive Decay Chain. UDSD. http://earthguide.ucsd.edu/virtualmuseum/images/Uranium238.html