Are Whanganui's silver birch trees causing asthma?

Silver birch trees are being cut down from a Whanganui residential street after complaints that they may be causing asthma.

A Whanganui District Council (WDC) spokesperson admitted there might be a link between the birch trees and incidents of asthma, however she insisted the trees were due to be replaced in any case.

Whanganui East residents, Mel and Cheryl Wheeler, in Young St say the thousands of silver birch trees that cover the city are to blame for their asthma.

In March, a University of Otago study revealed that Whanganui had the highest number of asthma cases in New Zealand.

The research showed one in four children suffered asthma and every year it kills six people in the district and hospitalises more than 160.

Two years ago Mr and Mrs Wheeler moved from Auckland to Whanganui with Mrs Wheeler's sister Trish Williams.

Whanganui residents Mel and Cheryl Wheeler with sister Trish Williams outside their home on Young Street. Photo/ Bevan Conley

About six weeks after the shift all three were greeted with itchy throats, itchy eyes and continuous coughing.

Mrs Wheeler, 64, said she had never suffered any respiratory distress until she moved to Whanganui.

"I am now on a daily dose inhaler. When I leave Whanganui my asthma goes away and when I return it comes back."

Mr Wheeler, 72, said he now has a wheezy chest, stingy eyes, and was constantly sneezing.

"Never once had I had a problem before I came to Whanganui."

Ms Williams, 62, said she was on two inhalers and just recently spent two weeks in hospital due to a flu that was caused by her respiratory distress.

"I'm the same, never had a problem before I moved here."

And they say they're not alone.

"After we started researching, we discovered that at least four of our neighbours also have respiratory problems but they had just never put two and two together," Mr Wheeler said.

Nearly a year ago Mr Wheeler complained to the WDC and was told there were plans to "revamp" the whole street.

Mr Wheeler said he'd been told that all the silver birch trees on Young St were coming out and would be replaced with a less toxic tree by Christmas.

"We never heard back from her until mid February because they had started but soon stopped...we were told that had to stop because the council had run out of money but they agreed to remove the one outside our property."

A Whanganui District Council (WDC) spokeswoman said she has had two Whanganui residents contact her expressing a concern that the birch trees were causing them respiratory problems.

"Yes birch trees can cause people some problems but everything with seeds has the potential to cause harm to sufferers of a breathing difficulty."

There was a plan to remove the trees along Young St because of their poor condition but there was not a definite time-frame of when this would be done.

"They are all reaching an age now where they are all starting to decline and getting in between the power lines and needing repeated pruning which causes wounds and weakness.

She said the tress would be taken out as part of a long term replacement plan similar to other trees.

"The council would not remove the trees solely for respiratory complaints without evidence to prove the trees were directly causing their asthma."