Radon is found in some petroleum. Because radon has a similar pressure and temperature curve as propane, and oil refineries separate petrochemicals based on their boiling points, the piping carrying freshly separated propane in oil refineries can become partially radioactive due to radon decay particles. Residues from the oil and gas industry often contain radium and its daughters. The sulfate scale from an oil well can be radium rich, while the water, oil, and gas from a well often contains radon. The radon decays to form solid radioisotopes which form coatings on the inside of pipework. An oil processing plant, the area of the plant where propane is processed, is often one of the more contaminated areas of the plant as radon has a similar boiling point as propane.

Radon, along with the noble gases krypton and xenon, is also produced during the operation of nuclear power plants. A small fraction of it leaks out of the fuel, through the cladding, and into the cooling water, from which it is scavenged. It is then routed to a holding tank where it remains for a large number of half-lives. It is finally purged to the open air through a tall stack, which is carefully monitored for radiation level.

Radon collects over samples of radium-226 at a rate of about 0.001 cm3/day per gram of radium. The radon (222Rn) released into the air decays to 210Pb and other radioisotopes, the levels of 210Pb can be measured. The rate of deposition of this radioisotope is dependent on the weather. In the early part of the 20th century in the USA, gold which was contaminated with lead-210 entered the jewelry industry. This was from gold seeds which had held radon-222 that had been melted down after the radon had decayed. The daughters of the radon are still radioactive today.

Depending on how houses are built and ventilated, radon may accumulate in basements and dwellings. The highest average radon concentrations in the United States are found in Iowa and in the Appalachian Mountain areas in southeastern Pennsylvania. Some of the highest readings ever have been recorded in the Irish town of Mallow, County Cork, prompting local fears regarding lung cancer. Iowa has the highest average radon concentrations in the nation due to significant glaciation that ground the granitic rocks from the Canadian Shield and deposited it as soils making up the rich Iowa farmland. Many cities within the state, such as Iowa City, have passed requirements for radon-resistant construction in new homes. A study made in December 2004 noted that the counties surrounding Three Mile Island have the highest radon concentrations in the United States and that this may be the cause of the increased lung cancer noted in the region.

The European Union recommends that action should be taken starting from concentrations of 400 Bq/m³ (11 pCi/L) for old houses and 200 Bq/m³ (5 pCi/L) for new ones. After publication of the North American and European Pooling Studies, Health Canada proposed a new guideline that lowers their action level from 800 to 200 Bq/m³ (22 to 5 pCi/L). The United States Environmental Protection Agency (EPA) strongly recommends action for any house with a concentration higher than 148 Bq/m³ (4 pCi/L),[47] and encourages action starting at 74 Bq/m³ (2 pCi/L). EPA radon risk level tables including comparisons to other risks encountered in life are available in their citizen's guide. The EPA estimates that nationally, 8% to 12% of all houses are above their maximum "safe levels" (four picocuries per liter – the equivalent to roughly 200 chest x-rays). The United States Surgeon General and the EPA both recommend that all homes be tested for radon.

Radon is a radioactive gas that can be inhaled into the lungs. In the lungs, radiation exposure to the lung tissue occurs. This exposure may lead to the onset of lung cancer five to twenty years later. It is estimated that 12% of all lung cancers are caused by exposure to Radon gas. It is also estimated that 15,000 to 22,000 of the 158,000 lung cancer deaths per year in the United States are caused by exposure to Radon and Radon progeny.

The risk of developing lung cancer from Radon gas exposure is directly related to the concentration of Radon gas to which one has been exposed, if the person is a smoker, and other individual factors. There is no safe level of Radon exposure. The US Environmental Protection Agency has established an action level of 4.0 pCi/L of Radon in indoor air. The best way to avoid illness is to reduce Radon exposure as much as possible and don’t smoke.

Other than lung cancer, Radon does not cause any other known ill effects. Because Radon is an odorless, colorless gas, you would be unaware that high concentrations are being breathed. Testing is the only means to determine if you and your family are being exposed to high levels of Radon gas.

It is important to realize that this number is an annual average, not a short-term exposure. At 4.0 pCi/L, a non-smoker would need to be exposed for 18 hours per day for a total of 70 years to have a 1 in 500 chance of developing radon-induced lung cancer. If you smoke, the risk rises to about a 1 in 35 chance. At higher radon levels, the risk increases as the exposure time decreases. For example, at 40 pCi/L, a non-smoker would only need 7 years of exposure to get the same 1 in 500 risk factor. However in all cases, long-term exposure is the key. Beware of pitchmen who use scare tactics to tout radon as an insidious killer, make outrageous claims for the number of people killed by radon, or paint it as a short-term danger.

Because it is radioactive and can lodge in your lungs, any exposure is potentially dangerous. If you smoke, the risk is even greater. However, the effect is cumulative over many years and short-term exposure is not generally considered harmful. In fact, the EPA tells a homeowner that if the initial radon test level is between 4 and 10 pCi/L, perform long-term testing (90 days up to one year) with an alpha-track kit to determine your long-term exposure or annual average before you consider mitigation to reduce the radon levels.

Lung cancer kills thousands of Americans every year. The untimely deaths of Peter Jennings and Dana Reeve have raised public awareness about lung cancer, especially among people who have never smoked. Smoking, radon, and secondhand smoke are the leading causes of lung cancer. Although lung cancer can be treated, the survival rate is one of the lowest for those with cancer. From the time of diagnosis, between 11 and 15 percent of those afflicted will live beyond five years, depending upon demographic factors. In many cases lung cancer can be prevented; this is especially true for radon.

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).And the rate among women is rising. On January 11, 1964, Dr. Luther L. Terry, then U.S. Surgeon General, issued the first warning on the link between smoking and lung cancer. Lung cancer now surpasses breast cancer as the number one cause of death among women. A smoker who is also exposed to radon has a much higher risk of lung cancer.

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. On January 13, 2005, Dr. Richard H. Carmona, the U.S. Surgeon General, issued a national health advisory on radon. Visit www.cheec.uiowa.edu/misc/radon.html exiting EPA for more on a study by Dr. William Field on radon-related lung cancer in women.

Secondhand smoke is the third leading cause of lung cancer and responsible for an estimated 3,000 lung cancer deaths every year. Smoking affects non-smokers by exposing them to secondhand smoke. Exposure to secondhand smoke can have serious consequences for children’s health, including asthma attacks, affecting the respiratory tract (bronchitis, pneumonia), and may cause ear infections.

Learning more about lung cancer. The following sources provide a wide range of good information about lung cancer, prevention, and treatment.

American Cancer Society -- www.cancer.org
American Lung Association -- www.lungusa.org
National Cancer Institute -- www.nci.nih.gov
Vanderbilt-Ingram Cancer Center -- www.mc.vanderbilt.edu/vicc
Memorial Sloan-Kettering -- www.mskcc.org/mskcc/html/44.cfm

Studies Find Direct Evidence Linking Radon in Homes to Lung Cancer - Two studies show definitive evidence of an association between residential radon exposure and lung cancer. Two studies, a North American study and a European study, both combined data from several previous residential studies. These two studies go a step beyond earlier findings. They confirm the radon health risks predicted by occupational studies of underground miner’s who breathed radon for a period of years. Early in the debate about radon-related risks, some researchers questioned whether occupational studies could be used to calculate risks from exposure to radon in the home environment. “These findings effectively end any doubts about the risks to Americans of having radon in their homes,” said Tom Kelly, Director of EPA’s Indoor Environments Division. “We know that radon is a carcinogen. This research confirms that breathing low levels of radon can lead to lung cancer.”

The amount of radon emanating from the earth and concentrating inside homes varies considerably by region and locality, and is greatly affected by the residential structure as well as soil and atmospheric conditions. Nearly every state in the United States has dwellings with measured radon levels above acceptable limits. The EPA estimates that 6% of American homes (approximately 6 million) have concentrations of radon above 4 pCi/L. Areas of the country that are likely to have homes with elevated radon levels are those with significant deposits of granite, uranium, shale, and phosphate, which are all high in radium content and, therefore, potential sources of radon gas. However, due to the many determinants of indoor radon levels, local geology alone is an inadequate predictor of risk. The only way to determine indoor radon concentration is by testing. Other factors that predispose homes to elevated levels of radon include soil porosity, foundation type, location, building materials used, entry points for soil gas, building ventilation rates, and source of water supply. Further research is being conducted on ways to predict which homes are most likely to have significant levels of radon.

ASTM E-2121 is a standard for reducing radon in homes as far as practicable below 4 picocuries per liter (pCi/L) in indoor air. Radon test kits are commercially available. The kit includes a collector that the user hangs in the lowest livable floor of the house for 2 to 7 days. The user then sends the collector to a laboratory for analysis. The National Environmental Health Association provides a list of radon measurement professionals. Long term kits, taking collections for up to one year, are also available. An open-land test kit can test radon emissions from the land before construction begins. The EPA and the National Environmental Health Association have identified 15 types of radon testing. A Lucas cell is one type of device.

Radon levels fluctuate naturally. An initial test might not be an accurate assessment of your home's average radon level. Transient weather can affect short term measurements. Therefore, a high result (over 4 pc/l) justifies repeating the test before undertaking more expensive abatement projects. Measurements between 4 and 10 pc/l warrant a long term radon test. Measurements over 10 pc/l warrant only another short term test so that abatement measures are not unduly delayed. Purchasers of real estate are advised to delay or decline a purchase if the seller has not successfully abated radon to 4 pc/l or less.

The National Environmental Health Association administers a voluntary National Radon Proficiency Program for radon professionals consisting of individuals and companies wanting to take training courses and examinations to demonstrate their competency. A list of mitigation service providers is available. Indoor radon can be mitigated by sealing basement foundations, water drainage, or by sub-slab de-pressurization. In severe cases, mitigation can use air pipes and fans to exhaust sub-slab air to the outside. Indoor ventilation systems are more effective, but exterior ventilation can be cost-effective in some cases.

Modern construction that conserves energy by making homes air tight exacerbates the risks of radon exposure if radon is present in the home. Older homes with more porous construction are more likely to vent radon naturally. Positive-pressure ventilation systems can be combined with a heat exchanger to recover energy in the process of exchanging air with the outside, and it should be noted that simply exhausting basement air to the outside is not necessarily a viable solution as this can actually draw radon gas into a dwelling. Homes built on a crawl space can benefit from a radon collector installed under a radon barrier (a sheet of plastic that covers the crawl space).