KEY POINTS:
Researchers have cleared the air slightly over the impact of pollution, finding virtually no effect on healthy teenagers exposed to a winter of smog.
The researchers also found that staying indoors provided no protection from air pollution.
The ground-breaking study conducted in Christchurch, often tagged the worst city in New Zealand for air pollution, followed teenagers over a winter season, when emissions from wood fires are at their worst.
The lung function of 93 students boarding at Christ's College was tested morning and night.
For 26, who have asthma, it was found there were "small decreases in lung function during very high pollution days".
"The majority of students, on the other hand, who didn't have respiratory problems, were not affected," lead investigator Dr Michael Epton said.
"But all students coughed slightly more on high pollution nights."
While the researchers say their study may dampen health fears, they concede it does not address the effects over long periods of exposure.
"I think it's important that we get a balance between understanding the effects of air pollution on health and not over-emphasising them," Dr Epton said.
He acknowledged there was a need to do similar studies on other age groups, but it was not easy to monitor people this way.
"We are very proud of this study because it is the first time that anyone has really tried to look that closely at a group of people like this."
Dr Emily Wilton, who heads the air quality consulting firm Environet, said the study was useful because it followed individuals and the effects on them rather than statistics on people.
However, she cautioned it was looking at a group that was not typically most at risk from air pollution, such as the elderly.
"It's not looking at the chronic effects - how lung function changes over time."
Ken Taylor, director of investigations for Environment Canterbury, said even the minor effects on the teenagers were interesting.
He pointed out that during the winter of the study, the pollution was not "excessively high, as it can sometimes be in Christchurch".
Dr Epton said the study contradicted the myth that people could escape pollution by going indoors and shutting the door.
"Our tests show very little difference in concentrations of ... particulates between indoors and outdoors."
The air pollution toll
According to a study released last year, each year in New Zealand air pollution causes:
- 1079 premature deaths.
- 1544 extra cases of bronchitis and related illnesses.
- 703 extra hospital admissions for respiratory and cardiac illnesses.
