The Victorian Government’s Air Quality Strategy and Air Quality Improvement Precincts aim to address local air quality in Melbourne's inner and outer west.

These initiatives are focused on ensuring decisions made on air quality and its impact on human health and the environment are informed by strong science and data.

EPA Victoria has been working with the Inner West Air Quality Community Group and Network to understand local air pollution activity.

This includes comparisons between the West Gate Tunnel Project stations and our metropolitan Melbourne air monitoring stations in Alphington, Brooklyn, Footscray and the Central Business District.

Air quality monitoring took place between July 2016 to December 2022.

This data is included in the Analysis of West Gate Tunnel Air Quality Data Report, with an overview of the findings below.

What we measured

The air quality measures reviewed at the tunnel and EPA stations were: 

• PM2.5 (particulate matter less than 2.5 microns (µm)) 
• PM10 (particulate matter less than 10 µm) 
• CO (carbon monoxide) 
• NO2 (nitrogen dioxide).  

This report compares the air quality measures against Victorian Environmental Reference Standards (ERS). 

What we found

Airborne particulate (PM2.5 and PM10) concentrations fluctuated over the years across all stations, due to a range of local air pollution sources and weather conditions.

All stations found particulate matter concentrations higher than the ERS, at some point during the 5.5-year data period, though the frequency and duration of elevated levels varies between stations. 

This was likely due to:

• widespread smoke from the 2019-2020 bushfires 
• local pollution sources including industry and transport
• wood heater emissions.  

Restricted activity and movement during the pandemic and reduced bushfire impacts in 2021, and weather linked to La Niña in 2022 contributed to lower particulate concentrations at all stations. 

In 2021 and 2022, air pollution concentrations at the tunnel stations were consistent with measurements at EPA’s inner-west stations and were below the ERS.

Carbon monoxide did not go above the 8-hour ERS during the 5.5-year data period.

Three times, at the Brooklyn air quality station, the one-hour nitrogen dioxide concentrations were higher than the ERS. This was most likely due to vehicle emissions from the nearby West Gate Freeway.

What this means

The data showed that other factors that contribute to air pollution include:

• industry emissions
• smoke from woodfire heaters
• bushfire smoke
• windblown dust. 

The contribution to air pollution from these factors are highly variable over time. 

For example, weather and climate events can impact air quality when dry conditions exacerbate local dust impacts from industry sources or bushfire smoke contributes to large regional areas.

As a result, there may be periods of time where air quality is higher than the ERS.

EPA is focused on understanding sources and environmental conditions that may influence air pollution levels.

We continue to work with: 

• community
• industry
• government.

We also provide advice to community on managing exposure where necessary.

It is important to note EPA encourages anyone with concerns about impacts to their health should contact their local GP for specific medical advice. This scientific information should not replace medical advice or guidance.

What happens next

The data is a baseline for assessing future air quality once the tunnel opens and will help explore any future actions that may be needed.

EPA continues to work with the Department of Energy, Environment and Climate Action to implement the Victorian Air Quality Strategy.