Pollution from exhaust stacks


Global health experts agree that pollution from traffic exhaust poses serious health risks. Emissions include nitrous oxides and particulate matter that, when breathed into the lungs, causes respiratory diseases such as asthma and emphysema, and cancer. This has been repeatedly proven across numerous independent studies across the world(1).

Medical experts universally state that there is no safe level of exposure to these types of cancer-causing emissions, and that children and the elderly are particularly vulnerable.

Doctors have specifically been concerned with levels of airborne toxins from other similar tunnel projects around Sydney, such as the recently completed NorthConnex(2).

Premier Gladys Berejiklian announced in July 2018 that “the proposed ventilation stacks are now away from schools, away from where people live”(8). Education minister Rob Stokes has said there is “no way in hell he will countenance exhaust stacks being built anywhere near a school”(3).

However the facts are that unfiltered exhaust stacks for this project will be very close to homes and schools, located:

  • on Balgowlah Golf course (within 100m of homes, 300m of schools, child care facilities and aged care)
  • near Kirkwood Ave, Seaforth (within 300m of homes)
  • at Ernest St, Cammeray (within 100m of homes, and 300m of Anzac Park Public School).


Watch a video from Dr Ray Nassar explaining the health impacts from exposure to traffic exhaust here: https://vimeo.com/278243564


Exhaust emission dispersal


The science of exhaust emission dispersal from stacks is complex and requires detailed modelling for each precise location, a process that has been undertaken in the EIS. Marketing information from the government tells us that “the exhaust air is indistinguishable from surrounding air”, however the reality is a different story.


The figures released in the Beaches Link EIS show increased levels of pollution at various sites in the region due to the project – incorporating pollution from both exhaust stacks and surface roads. These include:

Punchinello Kindergarten
– 0.1mg/m3 (approx 3%) increase in CO 1-hour maximum
– 0.9 μg/m3 (approx 5%) increase in NO2 annual average
– 0.2 μg/m3 (approx 1%) increase in PM2.5 1-day maximum
St Cecilia’s School
– 0.25 μg/m3 (approx 1%) increase in PM2.5 1-day maximum
North Balgowlah Public School
– 3 μg/m3 (approx 2%) increase in NO2 1-hour maximum
RWR receptors (individual dwellings not identified by address)
– 0.4 mg/m3 (approx 10%) increase in CO 1-hour maximum
– 1.5 μg/m3 (approx 5%) increase in NO2 annual average
– 15 μg/m3 (approx 8%) increase in NO2 1-hour maximum
– 6.1 μg/m3 (approx 12%) increase in PM10 1-hour maximum
– 2 μg/m3 (approx 8%) increase in PM2.5 1-day maximum


Balgowlah Boys High School was not included as a community receptor for modelling, despite being within 300m and overlooking the exhaust stack.

The community are also concerned that pollution exposure figures modelled in the EIS for particulate matter (PM10 and PM2.5) are averaged over a 24-hour period. This effectively hides high exposure times (i.e. during peak hour) by averaging them with low exposure times when there is little traffic.

Whilst the increases are numerically small, they are added to already high background levels of pollution in the urban environment, and contribute to a significant reduction in air quality from the project (particularly compared to improved public transport that takes vehicles off the road). They show the increased exposure from the tunnel, new roads and exhaust stack is certainly not “indistinguishable” as described by TfNSW.



In terms of other locations that will be affected, exhaust stack function encompasses the surrounding terrain, heights of nearby buildings and all weather patterns and events. Many factors influence the ability of the concentrated emissions to disperse effectively, including air temperature, exhaust temperature, speed of exhaust expulsion, wind direction and speed.

The NSW Chief Scientist report reveals all stack designs involve increased air toxins up to a 1200m radius from an exhaust stack(4). Government documents recently leaked to the media revealed “plume downwash” is also a concern at the site(5), where additional toxins are drawn to ground level.


The diagram below shows the dispersal of concentrated emissions according to the NSW Chief Scientist report, with the red dots indicating various locations around the Balgowlah stack, including Seaforth Public School, Balgowlah Boys High, Bupa Aged Care Seaforth, Ellery Pde Seaforth and Woodbine St North Balgowlah.

NSW Chief Scientist diagram of plume dispersal


The Balgowlah exhaust stack is particularly problematic as it is located at a low point in the valley, meaning exhaust emissions will be distributed over homes and schools on the hills around it. This includes the tall apartments at Stockland Balgowlah, homes in Ellery Pde Seaforth, Woodbine St North Balgowlah, Maretimo St Balgowlah and everyone in between. Not only will thousands of residents be exposed to increased pollution levels, they will have a daily visual reminder of that fact.

The map below is from the Beaches Link EIS documents, showing the homes that are able to see the exhaust stack from their properties (Beaches Link EIS, Appendix V page 135)(10). The impacted residences are shown in purple, and also extend beyond the map shown.


The map below shows the similar impacts to homes surrounding the Seaforth exhaust stack which, due to the exhaust stack’s location on the top of a ridge, covers the far greater areas of Seaforth, North Balgowlah, Killarney Heights, Allambie Heights and Castle Cove. (Beaches Link EIS, Appendix V page 181)(11).The impacted areas are shown in pink, and are important because many residences have not been informed directly by TfNSW of impacts or community consultation.

Many requests have been made across Sydney for government to filter exhaust stacks, in line with tunnels of similar length in Europe and Asia being filtered. However the NSW government has refused; with the claim that it is inefficient and too costly. To do so would concede filtration reduces air toxins for public health and should be implemented in tunnels all over Sydney – but in the government’s view, it is too expensive and the health benefits are insufficient.


In addition to increased air toxins from exhaust stacks, exposure to vehicle exhaust will increase significantly for residents within a short distance of the tunnel entrances, with increases in traffic travelling to the tunnel, new roads being built and idling traffic queuing at new traffic lights.

But won’t electric cars fix the problem?


Unfortunately, the uptake of electric vehicles will not be the answer. The uptake of electric vehicles has been very slow in Australia compared to the rest of the world, and government policies have refused to provide subsidies supportive of the take-up(9). The most dangerous particulates come from diesel exhaust (from a truck fleet that will not be updated to low emission or electric trucks for many decades), and particles that break down from tyres and brakes that will continue to be a problem from all vehicles.

Electric and hydrogen cars bring their own problems; if there is an accident, the batteries are highly flammable and toxic when inhaled. Some countries are even considering banning electric vehicles in tunnels until these risks can be mitigated(6).

The NSW Chief Scientist report on trends in vehicle exhaust emissions states whilst regulatory changes mean new vehicles are cleaner, the increase in roads, number of vehicles and number of kilometres travelled mean total fine particulate matter emissions (from exhausts and tyre wear etc.) plateau and then increase over the next 10-20 years (Page 9)(7).


It is true that air quality overall has been improving in Australia, but as improvements are made and health benefits achieved, why should some in the community suffer airborne toxins significantly higher than others due to their proximity to unfiltered tunnel exhaust stacks and new traffic jams?

1) Air pollution: everything you should know about a public health emergency (The Guardian, November 5, 2018)


2) Doctors fear health impact of NorthConnex tunnel (SMH, September 1, 2014)


3) Exhaust stacks won’t be near schools, says Stokes (Manly Daily, July 19, 2017)


4) NSW Chief Scientist report on Tunnel Air Quality


5) Confidential NSW Government blueprint shows toll-road pollution stacks (ABC News, July 17, 2017)


6) Alternative fuels and the future of road tunnels and road tunnel design


7) NSW Chief Scientist: TP01: Trends in Motor Vehicles and their emissions (November 2018)


8) Tunnels will slash travel time between Northern Beaches and Airport, NSW Government says (ABC, 26 July 2018)


9) ‘Dumping ground’: Australia charged with discouraging electric vehicles


10) Beaches Link EIS, Appendix V page 135

11) Beaches Link EIS, Appendix V page 181