Cell phones dangerous at gas pump?

Oil companies are warning customers they could cause an explosion by using cell phones while they fill up at gas stations.

However, some -- including cellular manufacturers -- say the possibility of cell phones causing a spark that ignites a flash fire at the pump is the stuff of urban myths, not hard science.

Indeed, to some customers in Calgary, it's a baffling warning. "A cell phone? That's hard to believe," one told CBC News.

An advisory issued to the gas industry in July talks of "reports of cell phone explosions."

Roger Poirier, of the Canadian Wireless Telecommunications Association, says there has never been a fire or explosion caused by a cell phone -- any place in the world.

"A lot of what we've heard are probably urban myths," he told CBC News.

The stories have been featured on "urban myth" web sites. Even so, Imperial Oil has ordered its workers across Canada to tell customers to turn off their phones when pumping gas. If not, the gas will be turned off for them.

John Wastle, of Ontario's Technical Standards & Safety Authority, says there are a number of ways that cell phones can generate a spark. "And of course in the right circumstances, in a flammable environment, that could lead to a flash fire," he said.

The industry admits the chance of an explosion is remote, but says the new rules can't hurt.