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Pollution levels from NorthConnex motorway smoke stacks set to quadruple

Residents have flagged new concerns over air quality impacts from the new NorthConnex motorway after pollution level forecasts were quadrupled by the state’s road authority.

An artist impression of the NorthConnex ventilation stack.
An artist impression of the NorthConnex ventilation stack.

Residents have flagged new concerns over air quality impacts from the new NorthConnex motorway after predicted pollution levels from unfiltered smoke stacks were quadrupled by the state’s road authority.

Documents released by Roads and Maritime Services show the amount of “volatile organic compound” (VOC) emissions to be released from the project’s ventilation outlets will measure up to 4mg per cubic metre — an increase from the 1mg limit outlined in original plans.

An impression of the southern ventilation outlet, as viewed from the M2 at West Pennant Hills.
An impression of the southern ventilation outlet, as viewed from the M2 at West Pennant Hills.

The department blamed a data entry error for including the lower limit, and said the 4mg measure would bring the project in line with other major tunnels including WestConnex.

But the error has sparked questions among residents about potential health impacts on homes and schools surrounding the outlets — along with calls for the stacks to be fitted with filtration devices.

Documents show the increased limit would apply to both the northern and southern ventilation stacks that will be used to funnel exhaust out of the 9km tunnel.

Local resident and GP Samantha Lander said concerns included potential health impacts from VOC carcinogens including benzene, toluene and formaldehyde.

“Already as a GP and a parent who has children in the area I had concerns about the pollution levels and the fact they’re now quadrupling that figure is a big concern,” she said.

“They’re saying the increase is an acceptable limit but from a health perspective there really is no safe level of exposure. There are respiratory issues, exacerbation of asthma and also the longer term impacts.

“To say (the lower limit) was a typo is really hard to believe given how many people must have looked at the documents since they were released four years ago.”

Transport for NSW said the limits were increased to reflect incidents in the tunnel including car breakdowns causing traffic jams that would result in a “short term exceedence” of a 1mg emission limit.

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The department said the amendment would “not affect other conditions of the NorthConnex approval”.

“Transport for NSW values transparency with the community on all our projects (and) we have a modification on display for feedback to rectify an unfortunate historic transcription error,” a department spokesman said.

“The amendment will result in little, if any change to local air quality for the surrounding community and no mitigation measures are required.

“Supplementary modelling results show that regular operation of the tunnel would produce approximately five per cent or less emissions at a VOC limit of 4mg/m3.”

The increase comes after a Parliamentary Inquiry into the WestConnex motorway tunnels this year recommended filtration systems on all current and future motorway tunnels “in order to reduce the level of pollutants emitted from ventilation stacks.”

Georgina Taylor from the Northern Residents Tunnel Action Group said filtration would address many of the 1375 submissions lodged during the public consultation process.

Transport Minister Andrew Constance in his response to the inquiry ruled out the recommendation and instead outlined a “best approach to continue to reduce emissions at the source by adopting cleaner fuels and vehicles.”

The Environmental Protection Agency said it was satisfied the increase would not result in adverse air quality impacts based on air quality modelling commissioned by RMS.

The NorthConnex motorway is due to open to traffic next year.

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Original URL: https://www.dailytelegraph.com.au/newslocal/north-shore/pollution-levels-from-northconnex-motorway-smoke-stacks-set-to-quadruple/news-story/d1cf0990db7b2b39462d0a419833c3a7