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Independent Reports

Tunnel Air Quality

Advisory Committee on Tunnel Air Quality

The Advisory Committee on Tunnel Air Quality (ACTAQ) is chaired by NSW Chief Scientist & Engineer and consists of a range of experts and officers in fields related to road tunnels, air quality and human health.  This includes senior representatives from the Roads and Maritime Services and the NSW Ministry of Health (NSW Chief Health Officer), as well as an independent air quality expert, Dr Ian Longley from the National Institute of Water and Atmospheric Research (New Zealand).

The NSW Environmental Protection Authority, the Department of Planning and Environment and the Office of Environment and Heritage are observers to the Committee. Professor Peter Sturm, Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, Austria is a technical advisor to the Committee.

The Advisory Committee undertakes work to better understand air quality in association with road tunnels in Sydney, including within cabins, within tunnels, and external to tunnels in the local surrounds.

The Advisory Committee is also asked to provide advice to the Department of Planning and Environment on air quality aspects of relevant Environmental Impact Statements, which is undertaken so as to avoid conflicts of interest. This advice is published on the Department of Planning and Environment’s Major Project Assessments portal.

2023/24 Tunnel Air Quality Review

The Hon John Graham MLC, Minister for Roads, has requested that the NSW Chief Scientist & Engineer lead a review of the findings and recommendations of the studies and reports on the human health effects of traffic-related air pollution. The Review will consider recent monitoring data on operating road tunnels in Greater Sydney.

The review will provide scientific and technical advice about the potential benefits of installing filtration and air treatment systems in NSW road tunnels.

Terms of Reference (2023/24)

Reports from the Committee



Technical Paper - Development of Air Quality Impact DescriptorsAugust 2022

Technical Papers 1 - 9: Key Points

August 2019

Technical Paper 1 - Trends in Motor Vehicles and their Emissions

November 2018

Technical Paper 2 - Air Quality Trends in Sydney

November 2018

Technical Paper 3 - Health Effects of Traffic-related Air Pollution

November 2018

Technical Paper 4 - Road Tunnel Ventilation Systems

December 2019

Technical Paper 5 - Road Tunnel Stack Emissions

November 2018

Technical Paper 6 - Options for Treating Road Tunnel Emissions

November 2018

Technical Paper 7 - Criteria for In-tunnel and Ambient Air Quality

November 2018

Technical Paper 8 - Role of NSW Agencies for Tunnel Projects

November 2018

Technical Paper 9 - Evolution of Road Tunnels in Sydney

November 2018

ACTAQ Studies and Technical Reports (August 2014 - June 2019)

  • Advisory Committee on Tunnel Air Quality - Supporting reports from February 2016 - June 2019. These include:
    • Review of Ambient Monitoring Data from Two Sydney Road Tunnels (M5 East & Cross-City)
    • Studies and background information to inform the in-tunnel NO2 limit
    • Optimisation of the application of GRAL Model in the Australian context
    • Review of In-Cabin CO2 Levels
    • Comment on Australian Vehicle Emissions Discussion Paper
  • Advisory Committee on Tunnel Air Quality Initial Report (August 2014) and Technical Papers 1-11 (August-September 2014)

ACTAQ Terms of Reference

To provide advice to the NSW Government based on national and international practice and experience with motorway tunnels that will:

  • Enable setting of performance based standards for emissions associated with road tunnels.
  • Recommend appropriate monitoring, compliance and reporting mechanisms to support public confidence in the operation of road tunnels.
  • Provide ongoing advice to Government on air quality issues arising from the assessment and operation of road tunnels.

ACTAQ Membership

  • NSW Chief Scientist & Engineer (Chair)
  • NSW Chief Health Officer
  • Chief Executive RMS
  • Dr Ian Longley, Senior Urban Air Quality Scientist, NIWA, New Zealand

The Chair of the committee retains the right to engage additional independent advice to support its considerations


  • Executive Director Priority Projects Assessments, Department of Planning & Environment
  • Director Reform and Compliance, EPA
  • Director Climate and Atmospheric Science, OEH

Technical Adviser

  • Professor Peter Sturm, Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, Austria


  • Director Environment, Senior Environmental Specialist (Air Quality), RMS