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Air quality portal

NSW Government | Roads and Maritime Services | Air quality portal

Air quality portal

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Filtration

Did you know there are no tunnels in Australia that are filtered?

A commonly asked question is why filtration systems are not installed in Australian tunnels as part of their tunnel ventilation system.

Studies have found filtration systems would not provide any measurable improvement to the air quality in the surrounding community.

In NSW we have an Advisory Committee on Tunnel Air Quality, which is chaired by the NSW Chief Scientist & Engineer and consists of a range of experts in fields related to road tunnels, air quality and human health. This includes the NSW Chief Health Officer, and an independent, international air quality expert.

The Committee released a report in relation to road tunnel air quality, which found emissions from well-designed road tunnels cause a negligible change to surrounding air quality, and as such, there is little to no health benefit for surrounding communities in installing filtration and air treatment systems in such tunnels.

This is because Sydney's motorway tunnel ventilation outlets are designed and operated to propel tunnel air high into the atmosphere. Once in the atmosphere, the ejected tunnel air is diluted 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.

This dispersion is so effective that if you put a filtration plant in the bottom of the ventilation outlet and had monitoring stations in the local area it would be difficult to measure a difference in air quality between when the filtration plant is working and when it is not. Remembering that filtration does not remove all pollutants from tunnel air so regardless we still need to run ventilation outlets to protect local air quality.

Our major NSW tunnels are also continuously monitored at the ventilation outlet to control the ventilation system. Since the Lane Cove Tunnel, air quality monitoring data is required to be made publicly available on the tunnel’s website.

Monitoring tunnel air quality

Internationally there are few tunnels with filtration systems and those that do rarely use them.

Of the small number of filtration systems installed around the world, most have been switched off, or are currently being operated infrequently – in some cases only a few hours a year. Often they are used to improve in-tunnel visibility and rarely solely for environmental purposes.

Did you know the Stockholm bypass tunnel currently being constructed uses a longitudinal ventilation system to manage tunnel air quality with no filtration. Once open this will be one of the longest tunnels in the world - about 18 kms long.

Stockholm bypass project


Filtration systems also use large amounts of energy to operate, and has significant costs to both build and operate.

The best approach to reducing community exposure to motor vehicle emissions is to continue to adopt cleaner fuels and vehicles to reduce emissions at the source, rather than attempt to filter them out of the air once they have been released. This approach delivers the greatest environmental benefits as they will improve air quality for the community as a whole as motor vehicles and trucks travel throughout the state.

Demolition

State-of-the-art pulverisers and shears are jaw-like excavator attachments. They crush and cut away at the walls and floors of buildings during demolition.

We use them because they make significantly less noise than hydraulic hammers.

TBM dive site

Two tunnel boring machines (TBMs) will be launched at the Marrickville dive site. It will be a tunnelling support site and provide the services TBMs need to build the tunnels such as grout, water, power and spoil removal.

  • Noise wall construction
  • Noise wall construction
  • Noise wall construction

Noise walls

Noise walls are built at some sites to reduce the impact of noisy works on the community.

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Air quality - have your say

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Thank you for sharing your feedback with Roads and Maritime Services. This mailbox is monitored during business hours, between 9am and 5 pm, Monday to Friday.

We will answer your enquiry as soon as we can. To find out more about Roads and Maritime, please visit: http://www.rms.nsw.gov.au/

Regards,

Roads and Maritime Services

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PM2.5 pollution charts and maps data source: 'Ambient Air Pollution Database', World Health Organisation, 2018. For more information and full disclaimers regarding data collection, measurement, estimations and limitations view the WHO Air Pollution web page .

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Community consultation

We will be carrying out a community consultation where you can learn about the Gateway to the South works, ask questions about the project and give your feedback. Please feel free to drop in at the following locations:


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Wednesday 15 February 4:30pm-7:30pm


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Wednesday 15 February 4:30pm-7:30pm

Terms of use

This internet site is designed to provide educational information on air quality across NSW. Use of this internet site is subject to these Terms of Use.

Roads and Maritime Services makes no representations or warranties in relation to the accuracy or completeness of the information contained within this internet site or displayed by it, or the accuracy or completeness of any data (or other outcome printed or manifested in any other way) as a result of its use.

The internet site, or any data or other information displayed by the internet site is in no way binding on Roads and Maritime and may not be appropriate for your specific needs or circumstances.

The internet site may contain links to third party internet sites that are not under Roads and Maritime’s control and which Roads and Maritime does not sponsor or endorse. By linking to a third party internet site Roads and Maritime is not accepting responsibility for the content of that internet site or your use of it and makes no warranty as to its suitability. Use of any third party internet site is subject to the terms of that internet site.

Roads and Maritime makes no representation or warranty that the internet site will be continuously available or free from any delay in operation or transmission, virus, communications failure, internet access difficulties or malfunction in hardware or software. Roads and Maritime also reserves the right at any time and without notice to discontinue or modify the internet site in whole or part.

Subject to any responsibilities implied by law and which cannot be excluded, Roads and Maritime is not liable to you for any losses, expenses, damages, liabilities and claims whatsoever, whether direct, indirect or consequential, arising out of or referrable to the use of this internet site or its discontinuance, howsoever caused (including your reliance on any inaccurate or incomplete information or data contained within or displayed by the internet site) whether in contract, tort (including negligence), statute or otherwise. Roads and Maritime’s liability for breach of a condition or warranty implied by law which cannot be excluded is limited to the extent possible to the re-supply of the internet site.

What is PM10 and PM2.5?

PM2.5 are tiny particles of particle matter, thirty times smaller than a strand of human hair.

Air pollution in Australia is measured by six main contributors; 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.

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