TORONTO — Images of Mexicans donning surgical masks in a bid to prevent swine flu infection may make Canadians wonder if they should follow suit. But except in certain health-care settings, experts say such a step isn't warranted -- at least not yet.

Infectious disease specialist Dr. Andrew Simor said surgical masks are recommended for staff in the close confines of hospitals and long-term care centres to prevent transmission of flu viruses and other microbes from patients to care providers.

The risk of health-care workers contracting influenza from an infected patient is increased because of prolonged close contact and medical procedures that may cause the patient "to cough and splutter all over you," said Simor of Toronto's Sunnybrook Health Sciences Centre.

But when it comes to the public at large, wearing masks would have little benefit, he said. "Those things don't happen as you're sort of going about your daily business buying groceries or watching a movie."

"There is absolutely no data to suggest this makes any difference or is at all protective for any individual. Now that's not to say it's going to cause any harm, but there's no evidence to suggest that it's actually effective."

Simor said that in his opinion, there is no need for Canadians to rush out to buy protective masks. Instead, he stressed the importance of good hand-washing practices to prevent transmission of the virus.

"Good hand hygiene is critical."

Dr. Richard Besser, acting director of the U.S. Centers for Disease Control, echoed that advice, saying his agency is not recommending that people wear protective masks at work or elsewhere as a precautionary measure.

"As a doctor and as a parent, the issue of masks comes up and people say: `Wow, should I wear a mask? Is that going to protect me?"' Besser told a teleconference from Atlanta.

Besser said the evidence that wearing a mask has any value outside a health-care setting "where you are coming in direct face-to-face contact with someone who has an infectious disease ... is not very strong."

"I would rather people really focus on hand-washing, not giving that little kiss of greeting when you're meeting someone, of doing those sorts of things, covering your cough and your sneeze."

"And then if you feel more comfortable with a mask if you're in a community or a setting with ongoing disease transmission, then you could think about that."

Still, the question remains as to whether equipment with more protective clout would be needed should the current swine flu clusters blow up into a global pandemic.

Simor said the issue of whether the N95 mask -- which became part of the public lexicon during the 2003 SARS outbreak -- would be any more effective than a surgical mask during a flu pandemic remains "highly charged" in infectious disease circles.

But he said available scientific evidence suggests that in the vast majority of exposures, the more expensive N95 would not be needed.

"The possible exceptions to that are in aerosol-generating procedures like intubation and ventilation in a critical-care unit where there is a greater potential for the generation of smaller viral particles that a standard mask may not be adequate to filter out."