Tunnel air quality

NorthConnex has been designed to meet stringent in-tunnel and ventilation outlet air quality limits set by the NSW Environment Protection Authority and NSW Ministry of Health. Sampling and monitoring points are required to be established, and independently verified and audited in accordance with the Conditions of Approval. Once NorthConnex is open, there will be continuous air quality monitoring inside the tunnel and the ventilation outlets to demonstrate compliance with the air quality limits.

Condition E11 Project Modification 3 Approved

The Department of Planning, Industry and Environment (DPIE) approved a modification to Condition E11 on 20 December 2019.

Transport for NSW requested a modification of the NorthConnex Conditions of Approval to rectify an error. The VOC (volatile organic compound) limit was incorrectly listed as 1mg/m3 rather than the intended 4mg/m3.

The community were encouraged to have their say on the modification during the Department of Planning, Industry and Environment advertised display from 30 August until 12 September 2019.

The change is consistent with the 4mg/m3 limit that has been approved for all road tunnel projects in NSW since NorthConnex.

The Environmental Protection Agency (EPA) and NSW Health reviewed the proposal and are satisfied that the new limit will not change air quality impacts associated with the operation of NorthConnex.

The Modification 3 Approval and assessment documents are available here.

Ambient air quality

Part E of the NorthConnex conditions of approval specify pollutants to be monitored in the air surrounding the project (ambient air quality). These include Nitrogen Dioxide (NO2) and particulate matter (PM10 and PM2.5) which have ambient goals that if exceeded, trigger reporting and investigation to determine if emissions from the tunnel outlets contributed to exceedances.  The ambient air quality notification protocol has been approved by the Department of Planning, Industry and Environment in consultation with the EPA, NSW Health and the Air Quality Community Consultative Committee (AQCCC).

Local weather conditions are also monitored to understand their effect on air quality.

To understand more about air quality read the fact sheet or visit the Roads and Maritime air quality portal. 

There are currently six monitors operating outside the tunnel to measure the ambient air quality. The locations, determined in consultation with the Air Quality Community Consultative Committee, are listed below:

  • James Park, Hornsby
  • Carden Park, Wahroonga
  • Thornleigh Golf Centre, Thornleigh
  • Headen Park, Thornleigh
  • Ashley Avenue, West Pennant Hills
  • Larchmont Place, West Pennant Hills

Data from these monitors will be collected for at least 12 months to provide baseline measurements for when NorthConnex opens to traffic. The monitors will continue to operate for at least two years after the tunnel opens.

Monitoring results

All air quality results are independently collated and audited every six months. Click here to see real time data from the NorthConnex ambient air quality monitors. Reports are prepared at the beginning of each month to summarise the results of the previous month. All available reports are listed below.

Month/Year

Report summary

February 2020

There were no exceedances of the air quality goals for the month


Previous reports
January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018

If you would like a hard copy of any of these reports, please call the project information line on (free call) 1800 997 057, email enquiries@northconnex.com.au, or write to us at Community Relations Team, Locked Bag 1001, West Pennant Hills, NSW 2125.

NorthConnex Local Planning Air Quality Assessment Process

Under Condition of Approval E15, NorthConnex has developed the Local Planning Air Quality Assessment Process Report in consultation with local councils for their use.

The report provides guidance for council development controls and finds no predicted health impacts for existing buildings around each vent outlet. 

Under existing residential building height restrictions, there will be no impact on allowable development around the ventilation outlets.

There were no exceedances of the air quality goals at the NorthConnex Ambient Air Quality Monitoring Network for the reporting month.

There were no exceedances of the air quality goals at the NorthConnex Ambient Air Quality Monitoring Network for the reporting month.

There were no exceedances of the air quality goals at the NorthConnex Ambient Air Quality Monitoring Network for the reporting month.

There were no exceedances of the air quality goals at the NorthConnex Ambient Air Quality Monitoring Network for the reporting month.

There were no exceedances of the air quality goals at the NorthConnex Ambient Air Quality Monitoring Network for the reporting month.