How do you put the risk from radon into perspective, especially since all homes contain some level of radon gas in them and there is no “safe level” except zero?
I have found the following charts to be helpful in evaluating risk: (please click on the pictures for a full sized detailed view)
Radon Gas Chart Safety Level Relative Risk Factors
Radon Cancer Risk Chart for Smokers vs. Non-smokers
Notice that the risk for a radon level at the EPA action limit of 4 picoCuries/liter is similar to the same risk of dying in a car wreck. I have personally observed several residences that I have tested in Dallas county to EXCEED this limit including my own home.
Radon is linked to not just lung cancer, but recent epidemiological evidence also suggests that radon gas may also be a risk factor and contributor to
Acute Myeloid Leukemia (AML) 13 % – 25 % of all cases worldwide.
Below is a detailed chart showing the radioactivity pathway to radon from the original U-238 atom. Also shown are the different types of radiation:
Alpha Radiation – (from Radon-222 as an example) high energy helium nuclei (almost no penetrating power, but does a great deal of damage at close range to cells and DNA – will not penetrate outer layer of skin, but can cause direct harm to epithelial cells in the lungs if inhaled) It causes approximately 5 X the damage of gamma Radiation or X-Rays.
Beta Radiation – high energy electron (much lighter than an alpha particle but it has a greater penetration)
Gamma Radiation – high energy photon (essentially without mass but has a high penetration factor through shielding)
Penetration and of Alpha, Beta and Gamma Radiation
If you follow the diagram below, the radioactive decay of Radon-222 to Lead-210 results in the emission of 3 alpha particles, 2 beta particles and a discrete amount of gamma radiation. (the nature of which is an electromagnetic wave, not a particle) Because radon decay products (RDPs) are electrically charged particles, they readily adhere to suspended dust particles (which can be inhaled) or other surfaces in a phenomena known as “plate-out”. Either pure RDPs or the particles they are attached to can be inhaled.