Radon is a radioactive, colorless, odorless, tasteless noble gas naturally occurring as the decay product of radium. It is formed as part of the normal radioactive decay chain of uranium. Uranium is relatively common in the earth’s crust, but generally concentrated in ore-bearing rocks scattered around the world. Every square mile of surface soil, contains approximately 1 gram of radium, which releases radon in small amounts to the atmosphere. The major contributor to radon concentration in dwellings is soil gas which may enter indoor air spaces through floors by pressure – driven or concentration – driven flow; in most countries, the contribution from building materials, except in special cases, is usually minor by comparison.
The dose from inhaled radon gas is low in comparison to that from its short-lived radioactive daughters, which are isotopes of polonium, lead and bismuth. When inhaled, these deposit on surfaces of the human respiratory tract and the most significant doses arise from alpha irradiation of the bronchial epithelium. It is transformation of these stem cells that is believed to result eventually in cancer at these sites. The radiation dose delivered by radon daughters to the bronchial cells is the highest to any body tissues from natural background radiation.
If you breathe in radon, you have a greater chance of getting lung cancer. Radon is the second leading cause of lung cancer, second only to tobacco smoke. The combination of smoking and radon exposure can greatly increase your risk of developing lung cancer. There are no immediate symptoms from exposures to radon. You may not realize that you are being exposed to dangerous levels of radon until you or someone in your family is diagnosed with lung cancer.
The European Commission, having consulted the suggestions of the International Commission on Radiological Protection (ICRP), issued in 1990 the Commission’s Recommendation on “the protection of the public against indoor exposure to radon” (90/143/ Euratom), in order to harmonize Member States’ provisions for the application of the basic safety standard for the health protection of the general public against the dangers arising from ionizing radiation. According to the Commission’s Recommendation, the reference level for consideration of remedial action is taken as equivalent to an annual average radon gas concentration of 400 Bq/m3 for existing buildings. For future constructions, a design level is used, which is an annual radon gas concentration of 200 Bq/m3.
Radon is a radioactive gas. It comes from the natural decay of uranium that is found in nearly all soils. It typically moves up through the ground to the air above and into your home through cracks and other holes in the foundation. Your home traps radon inside, where it can build up. Any home may have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements. Radon from soil gas is the main cause of radon problems. Sometimes radon enters the home through well water. In a small number of homes, the building materials can give off radon, too. However, building materials rarely cause radon problems by themselves.
That’s the question that leads most people to think about testing their home or workplace for radon. There are many buildings where long-term exposure to radon-related radiation can be a serious health hazard. The only way to know for sure your radon exposure is to test the radon levels in the spaces where you spend time. Make sure that you do tests that give you information that is accurate enough to make a good decision.
You will need to do a long-term test to get a measurement that will help you decide if it is worthwhile to take action to reduce your radon exposure. By long-term, we mean 90 days or more. The 90 days should span a strong seasonal change when your house goes from closed conditions (continuous heating or cooling) to open or natural ventilation conditions. It is best if the test lasts for a year. Unfortunately, most of the radon tests being done today are short term, lasting only 2 to 7 days. That is too short a time to reliably estimate the average radon concentration over the typical time most people reside in their home because radon gas levels can vary tremendously from day-to-day and season to season. That means if you happen to measure during a short period when the radon is unusually high or low, you may be seriously misled.
There are two main methods used to test for radon gas and radon daughter products. The most popular involves a “passive” device such as an activated charcoal test kit that collects radon gas atoms or an alpha track device that has a small strip of special plastic that is “marked” when hit by radon’s alpha particles. “Passive” devices are later “counted” in a laboratory to give you your result. Another passive device called an electret has a plastic disc with a static charge. Electrets are used only by professional radon inspectors because of the expertise required and the expensive equipment needed for analysis.
The other main method is the use of an “active” device called a CRM (continuous radon monitor). These are mostly used by professional radon inspectors for short-term (48 hours) radon testing during a real estate transaction.
The biggest differences between passive and active radon testing methods are the cost and the level of expertise required for proper operation. The only devices suitable for the do-it-yourself radon tester are the activated charcoal test kits and the alpha track detectors.
Yes. In municipal water systems most of the radon will escape to the air during processing. It tends to be the smaller rural water systems and well water that may have elevated radon levels. Compared with radon entering the home through soil, radon entering the home through water will in most cases be a small source of risk. Radon gas can enter the home through well water. It can be released into the air you breathe when water is used for showering and other household uses. Research suggests that swallowing water with high radon levels may pose risks, too, although risks from swallowing water containing radon are believed to be much lower than those from breathing air containing radon.