Ever wonder why cell phones are advised to be turned off inside the hospital? Basically, that unassuming piece of communications equipment can kill. Not by radiation (a different matter entirely), but by the interference it causes other hospital equipment. In the worst cases, the interference can cause hazardous situations.

A study in the University of Amsterdam found effects of cell phone interference in 26 different hospital equipment. Some 48 kinds of disruptions were found, more than a half of them hazardous. Although the research studied "worst-case" scenarios, it asserts that hospitals should restrict cell phone usage in areas where it won't affect equipment.

Some effects weren't alarming, like causing monitor displays to display some interference, but others were potentially dangerous. Some of the effects they found include inaccurate measure of blood pressure, a mechanical ventilator completely switching off and then restarting, syringe pumps totally shut down without warning and without setting off an alarm, and causing an external pacemaker to pulse incorrectly.

The research suggests that cell phones should be used about a meter away from medical equipments or hospital beds.