Radon, a radioactive gas
Radon is an unstable noble gas, meaning that not only does it not have color or smell, but it also decays into smaller particles, releasing harmful radiation in the process. What's unique about this gas is that it occurs naturally in large enough quantities to be a significant threat to the average person. Just so you know how big of a threat, radon is the second largest contributor to lung cancer, just behind smoking. The EPA has estimated that as many as 21,000 deaths per year in the U.S. are caused by radon.
Radon is the second leading cause of lung cancer
Being 8 times denser than air at sea level, radon tends to accumulate in under-ventilated areas, like mines, basements and attics. This means that radon levels inside a house are significantly higher than outside a house, especially if you live in Iowa or the Appalachian mountains area. Usually this gas will enter your house through the ground. Radon is a decay product of uranium and thorium which can be found in deposits underground. When these decay, the radioactive gas is produced, and it will flow into any crack it can find. On average, every square mile of soil to a depth of 6 inches (2.6 km2 to a depth of 15 cm) contains 1 gram of radium (which decays to radon). That amount can vary widely by region, but radon is pretty much everywhere. Once radon finds its way out of the ground, it accumulates in poorly ventilated places and in water. The highest concentrations can be found in caves (like in mines) and in ground water because these places aren't open to the atmosphere and thus there is no where else for the radioactive gas to go.
Most mines now have radon reducing technology
Even though radon can easily get into our drinking water, we aren't in much danger from ingesting it. Radon concentrations in water tend to be fairly low, and we aren't exposed to it as often. Radon in the air, however, is a serious problem. Being one of the densest natural gases, radon gas can stick to dust particles and stick inside our lungs, exposing us to almost constant radiation. On the whole, radon concentrations in the air tend to be very low, and thus not much of a problem, but when there's an enclosed space, the radon level can get dangerous. This means that it's a good idea to test your own house for radon. The EPA recommends that an area should have a radon concentration of 4 pCi/L (picocuries per liter) or less, but lower levels can still be dangerous. Many test kits are readily available to the public so that you can test your own radon levels. Both long term tests (up to 1 year) and short term tests (2-7 days) are available, with a variety of techniques. It is best to start with a short term test, and then follow up with a long term test. If you do find that your house has high concentrations of radon gas, all you really need to solve the problem is proper ventilation. Just opening a window or turning on a fan might not work, however. Likely you'll need to instal a vent to pump the gas safely out of your house.
radon can be safely vented from a home
Whenever radioactive substances are mentioned a lot of people think of a glowing green material, just like we see in cartoons. In its gaseous state, radon does not glow, but, if you condense it down by lowering the temperature, it does begin to glow. It starts off with a yellow color and turns to darker orange-red as the temperature drops.
This is about the color of radon
I live in Iowa, where radon is in high concentrations, so I plan on devising my own way of measuring radon concentrations. If I succeed, I plan on posting my design, so stay tuned.