A RESEARCHER believes air quality would likely improve near where the NorthConnex motor tunnel ventilation stacks are being built at West Pennant Hills.
The Hills mayor Michelle Byrne, Hornsby mayor Steve Russell and Mitchell MP Alex Hawke all agree, saying it's because cars travelling on Pennant Hills Road will be pushed underground once the $3 billion twin nine-kilometre tunnels are built.
"The benefits are countless: our roads will be safer, our neighbourhoods will be quieter and our air will be cleaner," Cr Russell said.
But Christine Cowie, a research fellow at The Centre For Air Quality and Health Research and Evaluation, couldn't give the same guarantee as to people's health.
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Dr Cowie said her previous research into the health of people living near the Lane Cove Tunnel ventilation stacks showed no increase in air pollutants.
"We did see an improvement in air quality very close to the road, but this didn't translate to a change in any respiratory health outcomes," she said.
She said it was hard to predict outcomes, considering residents living near the proposed ventilation stacks on the Cumberland Highway/Pennant Hills Road interchange are already exposed to traffic-related air pollution from Pennant Hills Road.
"Our study didn't show a significant effect that we could attribute to the ventilation stacks," Dr Cowie said.
"If designed well it [the stacks] should work to disperse the pollutants over a wider area."
Roads and Maritime Services — not the Environment Protection Authority — monitors air quality, in and coming out of, road tunnels.
Hornsby Council residents Daniella Abdow and Graeme Scott remain worried about noise and air quality.
NorthConnex's southern stack looks to be built metres away from their homes on Gum Grove Place.
Mrs Abdow's five-year-old has asthma, and Mr Scott said his family already took a vote to move.
"It's upset our family quite badly," he said.
The southern stack is one of two outlets identified in the NorthConnex twin tunnel project linking the M2 and M1 (formerly the F3).
A northern stack is proposed for Wahroonga.
The Hills and Ku-ring-gai council areas will also be affected by the new motorway tunnel which is expected to open in 2019.
The federal government is contributing $405 million to deliver the three-lane tunnels.
■ The next NorthConnex community meeting is on Wednesday, March 26, 7pm to 9pm, at Pennant Hills Golf Club, corner Copeland and Burns South roads, Beecroft.
■ Tell us what you think.