Radon is an invisible, odorless, radioactive gas that is created when naturally occurring uranium in rock and soil decays. People breathe this gas in and while it is in a person’s lungs it decays into radioactive particles, which are trapped there while they, in turn, undergo further decay. It accounts for about 56% of all the radiation the typical person receives in a year, and can eventually lead to lung cancer. (1) (Your radiation exposure - Radiological Protection Institute of Ireland)
Even though radon has always been with us, until homes and buildings became well insulated it didn’t present much of a problem since the average concentration of radon in outside air is a low 0.4 picocuries per liter (pCi/L). (2) The real concern is that radon can accumulate to much higher concentrations in indoor air because over the years construction standards have improved resulting in better sealed homes. In such situations radon can seep into buildings through cracks in their foundations, through well water, or come in around water or sewer pipes, and increase in concentration. (3) The result is that the EPA estimates that the average indoor level of radon is 1.3 pCi/L and at this level over a lifespan it will cause between 3 and 13 lung cancer deaths per 1,000 people. (The Health Risk of Radon Gas – VSI Environmental) A level of 1 pCi/L is the risk equivalent of 20 chest x-rays per year, and a level of 4pCi/L is the risk equivalent of 200 chest x-rays per year. (Radon Myths and Facts – Radon Doctor) It’s estimated that radon causes about 21,000 additional lung-cancer deaths every year in the United States. By comparison drunk driving kills about 17,400 people a year, falls in the home 6,000 a year, and home fires about 2,800 a year.
Given this situation standards were necessary, and the EPA eventually determined that a reasonable action level was 4 pCi/L. Even at this moderate concentration it’s estimated that one in fifteen homes are above it, and over a lifespan there will be between an additional 13 and 50 people in 1,000 who will die from lung cancer. For those who smoke the issue is even more pressing since it is known that smoking synergistically interacts with radon, multiplying the risk of lung cancer for any given level of exposure. Because of these facts the U.S. Congress has set a goal that indoor radon levels should eventually be reduced to the same as outdoor levels, but the problem is that this can’t be done with the current technology and available resources. For now people can generally afford to reduce radon to around 2 pCi/L.
Radon levels do vary greatly within buildings, with the highest concentrations in the lowest areas, and above the first floor the problem largely disappears in many homes. To determine the level of radon in a building there are do-it-yourself kits as well as professional testing. The kits are of two types, short term (less than 90 days) and long term (greater than 90 days). The advantage of the short term kits is that they provide a quick understanding of the situation, while the long term ones give a better understanding of the average indoor radon level throughout the year. This is important since the concentration of indoor radon can vary greatly depending on such factors as how often windows are left open. Frequently both methods are used since they are both fairly inexpensive. However when selling a home these methods often aren’t sufficient and professional testing is necessary since independent documentation is frequently required.
If the levels are above 4pCi/L, there are several common methods available to address the problem. The simplest approach is to seal the cracks in the building’s foundations. Then the next step is a vent pipe system, which involves using a pipe and fan to suck radon from beneath the building’s foundation and vent it to the outside air. These methods aren’t excessively costly, and typically run about $1,200 for repairing a home if a contractor is used.
(1) Although the literature is generally of the opinion that lung cancer is the only health risk from radon, some people speculate that radon might also be a risk factor for Alzheimer’s. (Alzheimer’s – Lost Wanderer)
(2) It should be noted that, since the risk from radon is continuous, no level is safe. Even at the 0.4 level over a lifetime such exposure will lead to about 1-3 people in 1,000 to die from lung cancer.
(3) Radon levels in homes can get very high. In 1984 Stanley Watras was a construction engineer working on the Limerick Nuclear Power Generating Station in Pottstown, Pa. Before the plant had gone into operation he found himself setting off the radiation alarms when he was entering the plant. The problem was eventually traced to high levels of radon in his home, which had 4,400 pCi/L in the cellar, 3,200 pCi/L in the living room, and about 1,800 pCi/L in the bedrooms. (Radon – A Short History) This level presented an equivalent risk to him of smoking 135 packs of cigarettes a day, or 49,275 packs a year. (Stanley Watras – Wikipedia)
(A Citizen’s Guide to Radon: The Guide to Protecting Yourself and Your Family From Radon – EPA, Radon – EPA)
Tags: Alzheimer's, Cancer, Lung Cancer, Radiation, Radon
“Even at this level over a lifetime….” I take it you mean .4?
The superinsulated homes of the 1970s were especially prone to problems resulting from their very slow air exchange rates. But at least some modern superinsulated homes do much better, incorporating constant ventilation using air/air heat exchangers. e-colab.org
Yes, 0.4 is correct. I also modified that footnote to remove any uncertainty.