About 100 Dunedin Passenger Transport drivers have been issued with masks, but company director Kayne Baas said it was drivers' choice whether they wore them.
The company would also place anti-bacterial hand gels in buses for drivers' use.
Drivers handled money all day, so the gel was designed to help protect them from infection, Mr Baas said.
[comment caption=Is the wearing of masks premature or sensible?]The company was also stepping up its cleaning and disinfecting of handrails on buses.
It was not acting on any special advice, but had decided to take this action, which he described as "reasonably expensive", to reduce the infection risk for passengers.
Otago and Southland medical officer of health Dr Marion Poore said the effectiveness of wearing masks in community settings and homes was limited.
They had to be the correct type, put on and taken off correctly and disposed of properly, she said.
"They are uncomfortable to wear for a long period of time and can give a false sense of security."
Frequent and thorough hand washing and drying was the most effective way to prevent the spread of illness, along with cough etiquette, staying at home when sick, and staying 1m away from others, Dr Poore said.
Other bus companies were not so enthusiastic about such measures at this stage.
Citibus general manager Tony Collins said, when contacted, it did not appear the situation in Dunedin so far was any different from other years with regard to winter illness.
If the situation changed and there was a swine-flu outbreak, the company had "quite stringent" plans to follow.
In the meantime, wearing masks did not seem "a very friendly approach to the public".
Otago Road Services manager Brent Sutherland said the company was monitoring the situation and had not seen the need for masks at this stage.
New Zealand Taxi Federation Dunedin spokesman Bill Colley said the wearing of masks was not something likely to be favoured by taxi drivers.
Wearing a mask as a taxi driver was impersonal and created a screen between the driver and passenger, which could offend some people, he said.
Taxi drivers' code of conduct advised them never to put anything in their mouths until they had washed their hands.
