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The Effects of Radon Gas Exposure

Radon is the 86th element of the periodic table, and a gas produced by the radioactive decay of uranium. In the United States, exposure to naturally produced indoor radon is likely the second leading cause of lung cancer, after smoking. The potential hazard posed by radon depends on its airborne concentration, but prolonged exposure is a known cancer risk. While 6 to 7 percent of U.S. homes are estimated to have unhealthy radon concentrations, mitigation to safe levels is fairly simple.

  1. Radon's Origins

    • In nature, radon emerges from the "decay chain" of naturally occurring uranium-238 in the soil. Normally uranium occurs in tiny concentrations of only a few parts-per-million (ppm). As the uranium naturally undergoes radioactive decay, it eventually forms an isotope of the element radium. As the radium continues along in the decay chain, it forms radon gas. Because uranium-238 has a very long half-life (4.5 billion years), radon exposure will be an enduring health concern.

    How Radon Meets Humans

    • When the decay chain reaches radon, its gaseous state lets it escape from soil or rocks and move upwards. If there's a building in their path, the radon atoms can enter it through natural cracks and imperfections in the foundation. Underground mines can also be substantial sources of radon exposure to workers.

    How Radon Causes Damage

    • When radon undergoes natural radioactive decay, it emits alpha particles. While these particles are fairly harmless outside the body, they can cause substantial damage to cellular DNA when emitted inside the body; such as when air containing radon has been inhaled into the lungs. Alpha particles can initiate chain reactions that break apart molecular links holding the DNA chain together, causing errors in a cell's genetic code.

      Sometimes damage to the DNA strand can be repaired by the body. However, sometimes it can't. While cells with damaged DNA often die, occasionally the damaged code can cause a cell to begin reproducing out of control. As the amount of inhaled radon increases, so does the number of alpha particles emitted inside the lungs, the number of cells damaged by the alpha particles and the risk that one of those cells could eventually become cancerous.

    Measuring Radon Concentrations

    • Two scales can be used to measure radon's radiation hazard. The first measure is in picocuries (pCi), which measures radiation intensity. The EPA mandates a radon "action level" of 4 pCi per liter of air--the concentration at which radon mitigation is necessary. The other measurement, becquerels (Bq), measures the number of radioactive decays taking place each second in a given space. The EPA has mandated an action level of 150 Bq per cubic meter. Either measurement is sufficient to determine an unhealthy radon concentration.

    Reducing the Risk

    • An evaluation of radon risk starts with a radon test. A radon test kit can be bought online and in many stores, and is sent to a lab to obtain results. The full cost of the kit and lab fee will usually run about $20 to $50.

      Radon mitigation strategies include improving ventilation, sealing visible cracks in the foundation and usually installing a sump fan to draw the radon-concentrated air underneath the foundation to the outdoors, before it can enter the house.

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