M8 Tunnel air quality

The WestConnex M8 includes a tunnel linking Kingsgrove to St Peters and a new extension which connects the M8 at St Peters to the M4. Transurban operates the WestConnex M8 in accordance with the Conditions of Approval established by the NSW Government and approved by the NSW Minister for Planning and Environment Protection Licence issued by NSW EPA.

Monitoring and measuring protocols for each pollutant and parameters are described in the glossary of terms. A Pollution Incident Response Management Plan is also in place as a requirement of the Environment Protection Licence.

The in-tunnel air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Visibility (K)

The external ambient air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Particles less than 2.5 micrometers in diameter (PM2.5)
  • Particles less than 10 micrometers in diameter (PM10)
  • Standard deviation in wind direction (Sigma theta)
  • Temperature at 2 metres (ºC)
  • Temperature at 10 metres (ºC)
  • Wind direction (degrees)
  • Wind speed (m/s)

Air Quality in NSW, particularly visibility and particle concentrations, may be impacted from both natural sources (such as weather, fires or dust storms) and human activities. We encourage you to visit NSW Office of Environment and Heritage website for a daily update on Sydney’s current and forecast air quality.

The ventilation outlet air quality monitoring shows data for:

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Oxides of nitrogen (NOx)
  • Solid particles
  • Volatile organic compounds (VOC)

Pollutant measuring locations


Ventilation outlet

External ambient

M8 Reports

M4 and M8 extensions Reports


The data uploaded to this website comes from air quality monitoring instruments and sensors installed in and around tunnel(s). Ambient air quality data is collected by third parties and may be subject to instrument or communication faults, weather or other environmental events, or server issues.

The data used in the compilation of this page has undergone only preliminary quality assurance checks. This data must be preliminary until a monthly quality assurance check/validation process has been undertaken by a person or organisation accredited by the National Association of Testing Authorities (NATA). For further detailed description and explanation of the quality assurance and data validation process, visit the Office of Environment and Heritage.

Validated data will become available on this page approximately one month after the end of the calendar month. For example, the January data which has been validated will become available at the end of February. Validated air quality data reports are published monthly on this page.

If you require more information or have questions about our site's disclaimer, please feel free to contact us by email at info@westconnex.com.au.