"Batman" premiered on this day in 1966, and ever since the Dynamic Duo has fought crime anywhere the bat signal (which means help is needed) shines. But you might have a threat sneaking into your home that even Batman and Robin can't catch. It's radon; an invisible, odorless gas leaking from natural radioactive elements deep underground. It seeps upward and slowly creeps into your home. In high levels, over a period of time if left unchecked, it poses health risks including cancer. Your best defense is a radon test kit. It's a small charcoal canister that you leave open for a few days and then mail in. You soon receive a report back. If levels are low, seal entry points like you would for water leaks. If levels are high, contact state and local health agencies for advice. Then open the Yellow Pages and flash the radon signal to call in a pro. And that's the On The House tip for today.