They are a great convenience, but the power windows in your car can also be a danger to your kids.

Safety watchdogs say close to 40 kids have been killed by power windows since 1990.

Each year, hundreds more are rushed to emergency rooms after getting caught in them.

Victims' families and safety groups have been demanding the government do something for years, and now it is.

Most cars have power window switches that go back and forth.

A kid can easily knock it or step on it, raise the window, and get caught. A parent who is not paying attention can also accidentally close a window on a child.

Now, when Chris Blake stops her SUV, she glances back before closing the window because she once rolled the window up on her daughter, Maggie, who was not hurt.

"It really did bring home just how dangerous those things can be," Blake said.

Other parents weren't as lucky.

Kevin and Bethany Faulkner were warming up their car on a cold winter night in Iowa and didn't realize their 3-year-old son Steven had hopped in and was alone.

"He got his knee on the power window button and before (we) knew it, it was up on his neck," said Bethany Faulkner.

"When we found him, he was already gone," said Kevin Faulkner.

Martha Passino is an RN at the nursery at Champlain Valley Pediatric Hospital and runs the car-seat program called Adirondack Safe Kids.

The strength of power windows can blow up balloons or dice vegetables.

"When you're talking about pressure on a windpipe, that doesn't take a lot of pressure to exert, so you're talking about the effects of the oxygen being cut off to the brain very quickly and very easily," said Passino.

As far back as the '60s, consumer advocate Ralph Nader asked the federal government to put out warnings about what he called "glass guillotines."

Three decades later, Janette Fennel, a mom from Kansas, is picking up where Nader left off.

"We really want people to understand that this is a danger," she said. The safety group she founded -- Kids and Cars -- helped convince the government to come up with new rules.

By 2008, automakers need to replace the switches that easily rock back and forth with safer designs, such as levers that need to be pulled up to raise the window. You can already find them in some cars.

Watchdogs say it's a good first step but they want the National Highway Traffic Safety Administration to go further and require power windows with auto-reverse in case something precious is in the way.

It's the same type of technology required for elevators and garage door openers.

"If something gets in the way of that window, it's going to go down," said Fennell.

Some foreign and luxury cars do have auto-reverse, although few offer it for windows in the back, where kids are supposed to be seated.

The new safety equipment can drive up the cost of a new car, but only by $50.

For more information:

www.kidsandcars.org www.consumerreports.org/powerwindowswitches

www.safecarsforkids.org www.window-safety.com

These 2004 model year vehicles offer window-retracting safety technology:

Acura TL
Audi A4, A6, A8, TT
BMW 3-series, 5-series, 6-series, 7-series, x3, x5
Cadillac cts, Deville, Seville, SRX, XLR
Chrysler 300 C
Ford 500, Explorer Sport Trac, Freestyle, Mustang
Honda Accord
Jaguar S-Type, XJ Series, X-Type
Lexus GS, GX 470, LS 430, LX 470, RX 330
Lincoln Aviator, LS, Navigator
Mercedes C-Class, E-class, M-class, S-class
Mercury Montego
Nissan Murano, Quest
Porsche Cayenne
Toyota Camry
Toyota Sienna
Volkswagen Beetle, Jetta, Passat, Phaeton, Touareg, S60, V70, S80, XC 90