Quick Dips

Balancing the Asthma Equation

Results of a recent study have undermined the theory that weather and allergens provoke asthma.

Massey University Plant Biologist Associate Professor David Fountain has been involved in a year-long study supported by a Health Research Council grant to Dr Ian Town of the Canterbury Respiratory Research Centre into the effects of climate and airborne allergens on asthma. the results were recently published in the British journal, Thorax.

The Blenheim-based study dismisses the previously-held belief that changes in weather and airborne fungal spore and pollen counts induce asthma.

The study focused on 139 asthmatics in Marlborough where study instigator and Wairau Hospital specialist Dr John Hedley is based. Participants kept daily diaries of their asthma activity and drug usage.

Professor Fountain co-ordinated the construction of the pollen count database which was used in the statistical analysis.

"We measured the pollen and spore levels every day for a year, and also weather data, to see if there was any relationship to asthma prevalence," says Fountain.

A forced air particulate trap instrument was used to monitor the air's pollen and spore content each hour. Pollen and spores impacted onto a revolving sticky tape which was then examined under the microscope, giving the numbers of pollen grains and spores per cubic metre of air.

Fountain says the in-depth, daily study was the first of its kind in New Zealand and possibly in the world. But he warns the results should not be seen as conclusive.

"As a pollen person, I noted the pollen levels were generally lower than usual. There were no days with high, by international criteria, pollen levels and that may have been a factor here. It definitely needs to be explored further before being dismissed from the equation."

There is no doubt pollen provokes asthma and northern hemisphere studies link asthma and pollen, he says.

Many New Zealand people are sensitive to spores and pollen, 33% in one study, but almost as many are sensitive to the house dust mite -- the current "hot favourite" for asthma cause here.