The study showed asthmatic students in Christchurch, considered New Zealand's worst city for air pollution, had a small decrease in lung function on smoggy days.

Launceston has battled wood fire pollution in the past and Australia Medical Association Tasmania president Haydn Walters said the results were not surprising.

"We already know that once you can see the haze the pollution is bad and admission to hospital goes up and so does the death rate," Mr Walters said.

The study also found those without respiratory problems did not show symptoms at low exposure to particulate levels.

Mr Walters said smog from wood burning was more harmful than smog caused by traffic and Launceston was becoming better at controlling its smog levels.

Australian Lung Foundation Tasmania Branch chairman James Markos said Launceston has only had two breaches of smog levels this year - from an allowable five breaches a year.

Launceston's last breach of air quality levels was on July 23 this year when particulate levels hit 62mg of PM10 particulates, above the allowable 50mg.

"At all three levels of government, a lot has been done to address Launceston's smoke problem," Dr Markos said.

"Because of the topography of the Launceston area, we trap smoke and smog."

Dr Markos said those who chose to burn wood ovens had the onus on them to do so correctly.