You can't see it, you can't smell it, and you may never even have heard of it, but it could be deadly. It's radon, a gas that comes from the breakdown of the radioactive element uranium.
"As it breaks down, it moves up through the soil column and enters our atmosphere," explained Jeremy Collinson of the Central District Health Department.
"It's the second-leading cause of lung cancer behind smoking in the United States and it causes more deaths than drunk driving," added Kris Vrooman of Energy Pioneer Solutions, which provides radon testing among other services.
Radon occurs naturally and is usually not dangerous unless it's trapped in an enclosed space such as a house.
"It just depends more on where your house is built than what kind of house you have. You have a new house or old house, that's really irrelevant. It's really more based on the soil that the house is based on," Vrooman said.
As January is National Radon Action month, many area health departments are offering both short-term and long-term test kits either for free or a small fee.
Health officials say Nebraska homes have very high rates of radon, with more than 80 percent of central Nebraska homes testing above the action level of four picocuries per liter.
"Even at the level of four picocuries per liter, that's the equivalent of smoking 10 cigarettes a day. And i know I wouldn't let my children smoke 10 cigarettes a day," said Vrooman. "Because it's colorless and odorless you don't think about it, but still quite a threat."
But experts say there are some simple ways to help reduce the radon levels.
"Some simple steps they can do is simply sealing up cracks in their basement foundation, their walls, any piping that comes into their basement or their crawl space, get that sealed. They could cover their crawl space with plastic," recommended Collinson.
And if those actions aren't sufficient, companies such as Energy Pioneer Solutions have radon mitigation systems to help reduce radon levels.