Four years ago, Transport Canada officials warned that air bags posed risks for women and urged design changes to reduce air bag injuries.

Last month in Toronto, Karol Steinhouse, a four-foot-10-inch, 90-pound woman, died in the sort of collision that concerned the officials.

In a 1996 paper presented at a conference in Melbourne, Australia, Transport representatives argued that air bags can do more harm than good.

"The incidence of bag-induced injury was greatest among female drivers," the report said. "Far greater attention to the protection requirements of female drivers needs to be given in federal regulations addressing restraint system performance."

Although the exact cause of Ms. Steinhouse's death has yet to be determined, the investigating coroner said the air bag in her 2000 Acura Integra was likely responsible for breaking six of her ribs and bursting her aorta.

Ms. Steinhouse, 47, an instructor at Ryerson Polytechnic University, was stopped at a red light when her car was rear-ended. The coroner said the seat belt or steering wheel might have inflicted some injury, but would not have killed the woman in such a low-impact accident. There is concern that women, who are typically smaller than men, are more likely to get hurt or killed by an air bag propelling out at speeds of up to 300 km/h. It was this concern that Transport Canada officials spelled out at the 15th International Technical Conference on the Enhanced Safety of Vehicles in Melbourne.

Analyzing crash data from Canada and the United States, they concluded that air bags substantially reduced head injuries in crashes. But they also found that the devices significantly increased the risks of people being hurt in minor accidents. Bag-related injuries tended to be minor ones to the face or upper body, but there were also serious injuries to other areas of the body, particularly if the person was sitting close to the steering wheel or dashboard.

The conference was told that in Canada -- where seat belt use is common -- air bags served "no useful purpose" in the "vast majority" of low-speed crashes. In those cases, injuries were either the same or worse than if there had not been an air bag. Their suggestion was to change the threshold speed -- the minimum speed the car must be travelling before the air bag is triggered.

By increasing the threshold to 24 km/h (from the current 20 km/h) they argued, the number of times air bags shoot open could be reduced by 75%.

Phil Edmonston, a consumer advocate and author of the Lemon-Aid car guides, is calling for a public inquiry into air bag safety. He said the government is too willing to blame victims for not wearing seat belts or sitting a certain distance from the bag instead of looking at ways to improve air bags.

"The public confidence in air bags has never been lower than what I see right now. And the anger and frustration from women in particular is palpable. I am really concerned."

But Transport Canada said improvements are being made.

Alan German, chief of Transport Canada's collision investigation division and one of the authors of the paper, said automakers have been increasing the threshold of air bags on their own. Since 1998, manufacturers have been curbing the speed with which air bags are deployed.

"That should make that situation a lot better," Mr. German said." Everything is moving in the right direction; you are going to reduce the number of deployments and you are going to reduce the incidents of injury because you have a less-powerful bag."

Transport Canada has traditionally used a crash dummy modelled after a man. It is developing dummies based on the size of small women, Mr. German said. He could not say when they will be used in crash testing.

Across Canada, the deaths of four adults and two children have been blamed on air bags since the devices were introduced in the early 1990s. Transport Canada said in three of those cases, the victims were not wearing seat belts. Three were women sitting close to the steering wheel.

Donald Huelke, a retired research scientist who conducted studies on air bags at the University of Michigan Transportation Research Institute, said there is no evidence that women, particularly those who are short, are at risk of being killed by air bags.

"The closer anybody sits to the air bag, the more in harm's way you are. That goes for men and women. In general, as we know, women cannot sustain as much blunt trauma as men," he said.

There is no law in Canada against disconnecting air bags, but many garages are reluctant to do the work because of the fear of legal reprisals. Transport Canada provides special forms to those who feel they are in danger, to help them get the bags switched off.