According to the U.S. Environmental Protection Agency, nearly 1 out of every 15 homes has elevated levels of radon, an invisible, odorless, radioactive gas that causes thousands of cases of lung cancer ever year.

Due to the underlying geology of the area, Carroll County and its neighboring counties have been classified as having the highest risk of elevated radon rates of the EPA's three-tier rating system.

The EPA has designated January "Radon Action Month." Here is some basic information on radon from Bill Long, director of the EPA's radiation program.

Q: Why does the EPA have a "Radon Action Month?"

A: "I think it's a way for us at EPA and with our state partners to put some spotlight on the issue, and we try to do it in the colder weather months [when] it's a good time to test your home for radon, because when you test your home for radon you want it to be closed up - you don't want to have a lot of windows and doors open," Long said.

Q: Where does radon come from?

A: "Radon comes from the ground, from the decay of uranium in the soil," he said. "It gets into the air as a gas and then collects in homes."

It's possible for it to get up to dangerous levels in homes, where it can cause serious health effects.

"In fact, it's very common for that to happen in the state of Maryland, so we need more people to know about it so they can take action to protect their families," he said.

Q: What are the health concerns with radon?

A: "Well, there's really only one, and it's a really bad one; it's lung cancer," Long said.

Radon is the second-leading cause of lung cancer in the country, and the leading cause among non-smokers.

"The tragedy is it's so easy to prevent, and the first step is a simple cheap step that everyone should take," he said, "which is testing their home."

Q: How do you perform a radon test?

A: "Testing is the only way to really know if you have a problem, and it's easy to do," Long said.

There are short-term and long-term tests, but the short term test is more common and the easiest to perform with do-it-yourself kits purchased from a hardware store or online, for about $10 to $15. Most long-term tests are performed by professionals, but can be done on your own as well, though are slightly more expensive.

The test should be performed in the lowest lived-in level of the home, he said. Once you get your results back, you can decide what the next step should be.

Q: If your home tests at or above the recommended action level of 4 picocuries per liter, how can the situation be remedied?

A: "One thing I want to mention is that it's not like 4 is dangerous and 3.9 is safe," Long said. "That's something that we try to make very, very clear to people - there's no 'safe' level of radon."

The EPA recommends that anyone with a reading of 2 or above when using a do-it-yourself test consider contacting a professional, he said.

According to the EPA's radon website, the average indoor radon level is estimated to be about 1.3 pCi/L, and about 0.4 pCi/L of radon is normally found in the outside air. The U.S. Congress has set a long-term goal that indoor radon levels be no more than outdoor levels, but there is no enforcement regarding radon levels.

Remediation is pretty simple, however, he said.

"It's essentially venting it from beneath your home's slab to above the house, and this is done with a pipe and a fan," Long said.

The cost of remediation can vary depending on the style and circumstances of your house as well as the area that you live in, he said, but generally it is in line with other home repair costs.

For anyone considering building a home in a high-radon area, the EPA recommends designing the home with radon remediation systems from the beginning, which is cheaper than fixing a problem later and will give you peace of mind.

Q: How often should that kind of test be repeated?

A: "That's somewhat dependent on how you live in the home," Long said.

Homeowners should test for radon when they first move in, and test again after any remediation work is done to rectify a high radon level.

Long recommends testing again if you start changing your living pattern in your home in a significant way, such as if you start using the basement level more frequently, or if your home goes through a major remodel or heating and air conditioning project.

Q: Is radon only a problem in basements?

A: Often people don't take radon seriously because they say they don't spend much time in their basement, Long said, but that's not the only place that radon can linger in your home.

"It can be a problem anywhere in the house, but it tends to be higher the closer you get to the ground," he said. "The only way to know for sure is to test."

And just because your neighbor may have done a test and found their results to be low, it doesn't mean that your home is safe, he said.

"There's lots of examples of high and low homes being right next to each other in the same neighborhood," Long said, due to geology, the foundation of houses, their air-tightness and other reasons.