But if a tornado is bearing down? The CDC recommends people use their hands to protect their heads. It makes no mention of a helmet.

For three months we tried to interview someone from the CDC, but the agency would only email a statement, which said: 'The scientific evidence from helmet use during tornadoes is inadequate to make a recommendation.' "

Today, the CDC issued a statement that affirms the importance of getting yourself to a safe place, such as a basement, or deep in a ditch or gully if you're outside. That's nothing new.

But the agency says it recognizes that people facing down a tornado want to protect themselves however they can. "Individuals may decide to use helmets to protect their heads," the agency says. And it's not telling people to refrain from doing so.

Since time is likely to be short in a heavy-weather emergency, the agency recommends that you have a helmet ready to go in your emergency kit, if you think you'll want to use one. You don't want to be fumbling around for one as a funnel cloud draws near.

Of course, a helmet alone is no match for a tornado. "For those who choose to use helmets, these helmets should not be considered an alternative to seeking appropriate shelter," the CDC says. "Rather, helmets should be considered just one part of their overall home tornado preparedness kit to avoid any delay."

For more information on how to prepare for a tornado, the CDC has some advice here.

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