Heather Vogt has agreed not to show her face around campus these days.

But it's not shame that keeps the 23-year-old University of Michigan senior in disguise. Ms Vogt is part of the first US study examining whether surgical masks, hand sanitiser and other preventive measures can slow the spread of the flu.

"It's a little warm and it's a little annoying to wear but for the most part it's pretty easy," said Ms Vogt, one of more than 1,000 students who have signed up for the experiment. "You just kind of ignore it after a while."

Not everyone Ms Vogt encounters has such a relaxed response to her mask.

"It's like the pictures you saw from China when they had the Sars breakout," said Dominique Lee, 21, a fellow student who was visiting Ms Vogt's dorm last week. "It also blocks communication. You're scared to talk to her because she has a barrier on."

Researchers are paying close attention to reactions like these. In addition to tracking whether the wearing of surgical masks is effective in slowing the spread of influenza, they are trying to get a handle on how readily it could be accepted by a general population in the event of a bird flu pandemic.

In some parts of Asia it is common for people with colds and flu to wear such masks as a courtesy to others, but it is not clear whether it would be accepted in the West.

"It has been identified as an important question in the pandemic planning process," said Arnold Monto, an epidemiologist in the university's School of Public Health who is leading the study. "Even if we find a relatively small effect, that may translate into a much larger effect during a pandemic and there will be greater motivation to wear the mask."

Severe Acute Respiratory Syndrome, or Sars, infected 8,000 people and killed close to 800 in 2003. It brought several affected Asian cities, such as Hong Kong and Guanzhou, to a near-halt at its height.

Experts are trying to learn from Sars to prepare for the next pandemic. Right now, H5N1 avian influenza is considered the most likely source of a pandemic, although it has infected just 272 people since 2003 and killed 166 of them.

Because making a vaccine could take years, and antiviral drugs are in short supply, researchers and public health experts want to find out if low-tech measures such as simple hygiene could help slow the spread of a new infectious disease.

Study participants are required to wear the cotton masks, which cover the mouth and nose and attach behind the ears, any time they are around other people in their dorms, with the exception of eating, showering and sleeping.

The assignment presents too much of a time burden for some, who note that the social stigma is also a deterrent.

"People wearing those kind of masks usually have some sort of lung disease or something," said Khalil Morrison, 21, who lives off campus, but had read about the study in the university's newspaper. "I'm afraid people would have the same reaction I did and steer clear of me."

To attract sign-up for the study in a short lead time before the height of the winter flu season, researchers hit students in a traditional vulnerable spot - their wallets. Students are paid $40 to $100 each, depending on their level of participation in the study, which is funded by the Centres for Disease Control and Prevention.

If they show flu-like symptoms and require an influenza test, they are paid an additional $25.

At a recent social gathering, mask-wearers shared war stories over ice cream sundaes.

One student said he planned to paint lips on his surgical mask for Valentine's Day. Others spoke of the possibility of a masquerade ball just for study participants.

"Getting people to change behaviours is not an easy thing," said Allison Aiello, an assistant professor of epidemiology, who is working with Dr Monto on the study. "It's tough... but I think the students themselves have a really good sense of tradition of doing important things for the community."

Each week Ms Vogt gets a fresh supply of surgical masks, complete with plastic bags for hygienic disposal each day.

Another batch of students will wear their masks in conjunction with a steady supply of hand sanitiser. A third, known as a control group, will do nothing other than track their regular behaviour during flu season. All of the participants agree to fill out weekly online surveys.

And while the incentives are nice, at least one student said he was motivated by a greater sense of purpose.

"It's for a good cause," said Ben Ruano, 20. "I'm personally doing it for the fact that it may help in the future."