How scary is this???

From Slate magazine:

On June 3, the bodies of two college students were found in a giant helium balloon in Florida. The week before, a 10-year-old in New Jersey collapsed at a birthday party after sucking helium from a balloon. Is helium really that dangerous?

It can be. Breathing in pure helium deprives the body of oxygen, as if you were holding your breath. If you couldn't breathe at all, you'd start to die in minutes—as soon as your body exhausted the supply of oxygen stored in the blood. But helium speeds up this process: When the gas fills your lungs, it creates a diffusion gradient that washes out the oxygen. In other words, each breath of helium you take sucks more oxygen out of your system. After inhaling helium, the body's oxygen level can plummet to a hazardous level in a matter of seconds.

You don't have to worry about fatal asphyxiation if you're sucking from a helium balloon at a party. At worst you'll keep going until you get lightheaded and pass out—at which point you'll stop inhaling helium and your body's oxygen levels will return to normal. Of more concern is the possibility that you'll hurt yourself when you fall down. (The boy in New Jersey bumped his head and needed three stitches.) It's far more dangerous to suck helium out of a pressurized tank: If the gas comes in too quickly, your lungs might burst and hemorrhage.

I had no IDEA this could happen. Silly helium, up there at the top of the periodic table. Noble gases, indeed.