The U.S. Centers for Disease Control and Prevention sent a fascinating little bulletin around to the media Thursday afternoon. The “CDC Statement on Helmets and Tornadoes” is a thoughtfully worded exposition on the merits of donning helmets to protect one’s head during a tornado, a type of storm that has killed 63 people so far this year and claimed more than 500 lives in 2011, according to the National Weather Service.

The statement emphasizes that finding safe shelter is key to surviving a tornado. “The safest place in the home is the interior part of a basement. If possible, get under something sturdy such as a heavy table or workbench. If outdoors, lie down in a gully or ditch,” the CDC advises.

Still, the agency says, “We understand that people who have seen the tragedy that tornadoes can impose are looking for any useful and effective ways to protect themselves.” The statement notes that it’s not aware of research demonstrating helmets’ protective value during a tornado, but allows that “individuals may decide to use helmets to protect their heads.”

But, the statement continues, “because the time to react may be very short, people who choose to use helmets should know where they are and have them readily accessible. Looking for a helmet in the few seconds before a tornado hits may delay you getting safely to shelter. For those who choose to use helmets, these helmets should not be considered an alternative to seeking appropriate shelter. Rather, helmets should be considered just one part of their overall home tornado preparedness kit to avoid any delay.”

I wondered what spurred the CDC to issue this specific message right now. Had there been reports that people were wearing helmets for tornado-protection purposes? CDC senior press officer Benjamin Haynes told me via e-mail that he wasn’t aware of any such reports, but noted that “around the time parts of Alabama were devastated with tornadoes, local meteorologists ([in] Georgia and parts of the Southeast) were suggesting helmets.”

“Not long after that,” he added, “CDC was asked for our recommendation on wearing helmets, and as the statement suggests, we don't have research on the effectiveness of helmet use to prevent head injuries during a tornado, but we do know that head injuries are common causes of death during tornadoes, and we have long made the recommendation that people try to protect their heads.”

CDC’s first recommendation, Haynes said, “is that people in the path of a tornado find a shelter or a tornado-safe room.”

That term “tornado-safe” is important, too. As this L.A. Times article published last week notes, a preliminary study by the CDC and the American Red Cross has found that many of those who died in the April 2011 tornados in Alabama had sought shelter, but apparently in structures not sturdy enough to withstand the extremely powerful winds a tornado generates.