There's a hidden hazard on a modern convenience we all take for granted the automatic door.
CBS News Consumer Correspondent Herb Weisbaum reports on the injuries that can occur when things go wrong.
They really don't look dangerous. But accidents involving automatic doors happen more often than you might think.
The risk of being hurt this way depends a lot on who you are and what you're wearing.
Automatic doors are everywhere. They are so common at stores, schools, hospitals and hotels we barely notice them. In fact, Americans pass through these electronic doors a billion times a week, almost always safely.
But don't tell that to Margaret Courts.
Her encounter with a department store door in Minnesota left her with a broken hip, broken arm and bruises visible weeks later.
Kathy Block became trapped in the doors of a membership warehouse store in California. "The door hit my right ankle, throwing my right leg over the front of the left," Block says. "As I got up to the door, I could see it was starting to close. But I couldn't back up, and I couldn't speed up because the door was coming too fast," she adds.
Overall, automatic doors have a good safety record. Accidents are rare. But when they do happen, they can be very violent.
One accident was caught on tape by a security camera at a Las Vegas casino.
A woman walking into the casino was hit by the sliding door and thrown to the ground.
Hard numbers are difficult to come by. The Consumer Product Safety Commission estimates there are hundreds, perhaps several thousand, of these accidents every year.
Those most at risk are elderly people and individuals with mobility problems.
CBS News hired safety consultant Lanny Berke to show how it can happen.
"Most people will move through that doorway in a second and a half. It's the elderly who move slowly and those that use canes and walkers that move slowly [who] are going to be the potential victims," Berke says. "The doors close fast, and they close with a lot of force," Berke adds.
That can be enough force to knock down an elderly shopper.
"And then if they are knocked down, one of the most common injuries for an elderly person is a broken hip. And that for an elderly person can be a death sentence," Berke says.
It's not just how fast you walk. Dark-colored clothing can also put you at risk because dark fabrics don't always show up well on motion detectors, the sensors that tell the door to stay open, Berke says.
Mabel was wearing dark clothing when an automatic door knocked her to the ground. The accident nearly killed her and left her with a disability and in pain, she says.
"What happened to me could happen to anyone," Mabel says. "It isn't the age; it could happen to anyone."
People in the automatic door industry admit some sensors don't see dark colors well. But they blame most of thes accidents on doors that are broken or out of adjustment.
The industry produced a training tape that encourages daily safety inspections at stores to make sure the doors are operating properly.
But safety expert Berke, who's investigated more than 100 automatic door accidents, says these safety checks aren't done very often. "In my experience, I have yet to find anyone doing it," he says.
The automatic door industry's trade group hopes stories like this will encourage daily checks at stores and other facilities with these doors. And the organization is considering some kind of public education campaign to make people more aware of the danger.
How do people protect themselves?
People need to use common sense. When you head through an automatic door, pay attention and keep moving. Don't stop halfway through to check your shopping list or look at a display.
And make sure your children don't stop or play in the doorway.
Safety expert Berke has this advice for seniors or those with mobility problems: If possible, have somebody hold the door for you or see if there is a manual door to use.
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