Earlier in this series on radon, we discussed the dangers of this radioactive gas and how ventilation can mitigate indoor build-up. But where exactly does radon come from, why does it become concentrated indoors, and how does it damage lungs enough to cause cancer?

Origins: Radon is the result of the natural breakdown of radium, an element created as Uranium and Thorium break down. While this radioactive decay sounds every bit as lethal as it can be to human health, the process is essential to life on Earth. Radioactive decay heats our planet’s core providing half the Earth’s heat, so while the resulting radon gas can kill us through prolonged exposure to concentrations, we wouldn’t be around without it either.

Since it is a gas, radon can travel anywhere and is typically emitted from igneous rock, soil, and sometimes private wells fed with ground water. Since radon forms naturally, concentrations depend on types of rocks in the area and geography, in general. Interestingly, aerial surveys of East Galway in Ireland have just confirmed the culprit in what has become a lung cancer hot spot: extensive areas of fractured limestone. The fractures create an easy pathway for radon to flow to the surface. Such studies will help create better mapping and radon-reduction projects for homes in the area.

The EPA has broken radon concentration levels in the United States into three zones. Zone 1 contains areas where the predicted average indoor radon levels are greater than 4 pCi/L. Zone 2 predicted levels range from 2 to 4 pCi/L, and Zone Three residents suffer significantly less radon-induced lung cancer risk at predicted levels of less than 2pCi/L. Still, this map doesn’t place your particular home in the clear if you reside in Zone 3. The EPA stresses that the only way to know your radon levels for sure is to test them.

Pathways: When radon gas permeates soil, it dissipates into the air. Outdoor readings vary between 0.02 and 0.75 pCi/L. We can’t do anything about those levels, and they don’t harbor the significant risk found indoors. The trouble comes when we build traps for the gas in the form of homes and buildings. By its very nature, a gas seeks out and seeps into even the smallest of avenues. Homes have plenty of them to invite radon in: cracks in the foundation, floor-wall joints, loose-fitting pipes, open tops, pores, and cracks in concrete blocks, exposed soil, sump pumps, and even building materials.

Your home’s structural imperfections don’t act alone, however. The nature of building construction creates lower or negative air pressure indoors than found in the soil. The difference in that pressure or pressure differential creates a vacuum, causing your home to literally suck up radon gas as if it were a good thing. These days, because we make the envelopes of our homes as tight as possible to save energy, much of the radon stays stuck indoors, drifting from our basements up through the first and second floors, with the highest concentrations remaining on the basement or ground level. Unable to escape the structure, a gas will, again, seep its way into whatever space it can find-including into your mouth, up your nose and into the confines of your lungs.

Pathology:During the 1950s and 1960s, studies were run on miners in answer to the high rate of lung-related disease and death in that group. Indeed, a connection was found between working underground amid high levels of radon exposure and lung cancer. Further studies compared radon levels in homes of those with lung cancer versus those without, as well as rates of death in geographic areas with varying levels of radon. It suspected by many scientists that radon might play a role in diseases such as Leukemia, Multiple Sclerosis, Alzheimer’s, and Parkinson’s Disease as well. While the connection to those diseases has not been confirmed, we do know that approximately 21,000 people–the average population of a small city–die of radon-induced lung cancer each year in the United States. Only smoking causes more lung cancer deaths.

But how does radon gas cause cancer? Radon, a result of radioactive decay, is also in a state of decay, breaking down into particles of radioactive elements such as lead, polonium, and bismuth. These particles get stuck in the lining of the lungs where they emit alpha radiation. This concentrated radiation, whether it hits a cell or the area around it, can set off a chain of chemical radical activity in cells. Damage to the cell’s DNA can occur. Once that happens, the cell will die, stop reproducing, or begin reproducing in an odd manner. That irregular cell behavior is how cancer-the uncontrolled proliferation of unconventional cells-begins. The risk of developing lung cancer grows with level of exposure as well as the number of years one is exposed. Likewise, the risk of lung cancer is reduced proportionally with reduction in exposure.

We’ve said it before, and we’ll keep saying it: Radon-induced deaths are preventable. Test your home levels. Then act to mitigate them as much as possible.

We are looking for feedback on your experiences with radon issues! Please drop us an email at klas@lowkwh.com, tweet, visit our Facebook or LinkedIn page and answer the following: Were you fully aware of the dangers of radon before reading this article? Do you know your radon level numbers? If so, what are they and do you feel you need to do something about them? Have you done something about them? What?

We hope this series will be food for thought in bringing more attention to the very real and unnecessary deaths caused by indoor radon exposure. The fact is, if you live above the Mason-Dixon line, you have a radon issue. Good ventilation practices are one way of taking control of home radon levels.