Frequently asked questions
Air quality monitoring
In NSW, the Department of Planning, Industry and Environment monitors, analyses and publishes information about air quality. They operate a comprehensive air quality monitoring network to provide you with accurate and up‑to‑date information about air quality. To find out more please visit www.dpie.nsw.gov.au/air-quality
Both state and federal governments are required to report against the six main air pollutants and our national standards for PM2.5 are one of the most stringent in the world.
Air pollution in Australia is measured by six main air pollutants; carbon monoxide, nitrogen dioxide, photochemical oxidants, sulphur dioxide, lead and particle pollution or particle matter (PM). PM is generally classified according to the size of the particles.
- Particles less than 10 micrometres in diameter are called PM10,
- Particles less than 2.5 micrometres in diameter are PM2.5,
- Particles less than 1 micrometre in diameter are PM1,
- Particles less than 0.1 micrometres in diameter are called ultrafine particles (UFPs).
It is important to note that PM10 includes PM2.5, PM1, and UFPs.
Sydney is a major international centre with residential, commercial, industrial, and natural occurrences such as bush fires, all contributing to air pollution. Motor vehicles are an important contributor to emissions, contributing 13 per cent of PM2.5, and 55 per cent of nitrogen oxides (which includes nitrogen dioxide (NO2) and nitric oxide (NO)). Other major contributors include wood heaters, which contributes 50 per cent of PM2.5, and industry – which contributes 18 per cent of PM2.5 and 13 per cent of oxides of nitrogen.
In NSW, the Department of Planning, Industry and Environment operates a comprehensive air quality monitoring network to provide you with accurate and up‑to‑date information about air quality. To find out more please visit www.dpie.nsw.gov.au/air-quality
In addition, air quality within major NSW tunnels is continuously monitored along the tunnel and at the ventilation outlet to control the ventilation system. This ensures the strict air quality limits outlined in the approval conditions are complied with at all times.
Since the Lane Cove Tunnel, air quality monitoring data is required to be made publicly available on the tunnel’s website, which is a requirement of the approval conditions. To find out more please visit:
Air quality regulation
The NSW Environment Protection Authority (EPA) regulates air quality and implements measures for managing and reporting air pollution. To find out more about the NSW EPA please visit: http://www.epa.nsw.gov.au/your-environment/air
Transport for NSW and private operators of future operating tunnels in NSW will be required to apply for an Environment Protection Licence (EPL) under the new requirements. Existing road tunnels in Sydney will also be required to apply for an EPL. Read more about the new regulatory requirements by clicking here.
Sydney’s air quality
Despite there being more cars on the road, a number of initiatives and technological developments have resulted in substantial reductions to vehicle emissions in the Sydney region over the past three decades. The number of cars is expected to further increase as the population of Sydney continues to grow, although total emissions from motor vehicles are set to fall further over the next 10 years due to the continued phasing out of older vehicles.
According to the World Health Organisation, Sydney’s air quality is good by national and international standards. The exception is during exceptional events such as bushfires. Explore the data here.
Sydney is a major international centre with residential, commercial, industrial, and natural occurrences such as bush fires, all contributing to air pollution. While motor vehicles are an important contributor to emissions, it should be acknowledged there are other significant sources of emissions. To find out more, download our latest factsheet.
Road tunnels can improve air quality for surrounding communities by removing vehicles from the surface road into an underground tunnel.
Motorists experience a smooth motorway to travel on, rather than being in congested, stop start traffic. This means less sudden braking, less wear and tear on vehicles and a reduction in emission levels on local roads.
With the expected increase in electric vehicles and other cleaner vehicle technologies over the next decade, we will see ongoing emission reductions from motor vehicles, even with more vehicles travelling on our roads.
Tunnel ventilation systems
Tunnel ventilation systems work by ensuring sufficient air flows within the tunnel to meet air quality requirements. In NSW, tunnels longer than one kilometre also have ventilation outlets, which eject tunnel air high into the atmosphere, through a combination of buoyancy and speed. Once in the atmosphere, the ejected tunnel air dilutes hundreds of times as it mixes with the surrounding air and becomes indistinguishable from background levels.
Ventilation outlets are vertical structures with large fans at their base designed to eject tunnel emissions high into the atmosphere, ensuring they are dispersed and diluted so there are no measurable effects on local or regional air quality.Each outlet is custom designed to take account of local tunnel air flows, terrain, surrounding buildings and weather to ensure effective dispersion under all conditions.
Our tunnels are required to meet stringent air quality standards using state-of-the-art ventilation and tunnel design.
Studies have found that filtration systems would not provide any measurable improvement to the air quality in the surrounding community, and as such, there is little to no health benefit for surrounding communities in installing filtration and air treatment systems in such tunnels. To find out more you can download the Initial Report on Tunnel Air Quality from the Advisory Committee on Tunnel Air Quality.
Elevated ventilation outlets are very effective at ejecting tunnel air high into the atmosphere through a combination of buoyancy and speed. This occurs by the warmer tunnel air (heated by vehicles using the tunnel) being ejected upwards at speed through the outlet by axial fans. This warm air continues to rise high into the atmosphere through natural buoyancy as it is warmer than the surrounding air.
Once in the atmosphere, the ejected tunnel air dilutes hundreds of times as it mixes with the surrounding air before mixing down to ground level resulting in little, if any, change to the quality of the air people breathe.
The tunnel ventilation systems are designed to operate effectively under all traffic and weather conditions.
Modern tunnel ventilation design ensures the operation of our tunnels meet strict air quality requirements set by the Department of Planning, Industry and Environment and the Environment Protection Licence issued by the Environment Protection Authority.
Our modern tunnels are designed to achieve:
- strict in-tunnel air quality
- no emissions from portals
- emissions from ventilation outlets that result in little, if any, change to the quality of the air people breathe.
Air quality within major NSW tunnels is continuously monitored along the tunnel and at the ventilation outlet to control the ventilation system. This ensures the strict air quality limits outlined in the approval conditions are complied with at all times.
The EPA regulates the ventilation outlets for all current and future operating motorway tunnels to ensure they meet air quality limits.
Tunnel ventilation systems generally work most efficiently and effectively when the ventilation outlet is positioned near the exit ramp. This is why the ventilation outlets for modern tunnels are located near tunnel exit ramps.
