Shocking air quality on rail network threatens passengers and staff

Warning: Sydney’s underground train system is a health hazard. Passengers and staff are being exposed to poisonous air containing more than twice the safe daily limits for particle pollution. And of further worry, authorities and state governments have kept the information secret for years.

The potentially serious health threat occurs when trains brake and accelerate when they arrive and depart underground platforms and friction between the carriage, wheels, tracks and brakes create tiny metal particles, known as PM2.5 and PM10. These then become dust or a gas that coagulates and drifts around underground stations and tunnels, being constantly stirred by passing services so they end up being freely inhaled by commuters and railway staff.

A Herald investigation tested air pollution and gas concentrations at 16 train stations above and below ground on the Sydney train network and the newer Sydney Metro Northwest, and uncovered an alarming presence of unsafe air. The worst reading came from platform 25 at Central Station, where we recorded PM2.5 readings averaged over a minute of 133 µg/m3. This is more than five times the recommended daily limit of 25 µg/m3 adopted by the NSW government. On platforms one and three at Town Hall we recorded PM2.5 levels more than double those at the closest outdoor air quality monitoring station on the days we tested. Air quality was even worse at deeper station platforms at Central, Wynyard, Macquarie University, Epping and North Ryde.

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Transport for NSW said it had “no significant concerns” raised about air quality and dust monitoring, and air quality management took place across the underground network. But University of Wollongong researcher Hugh Forehead warned workers – station staff on Metro and city circle lines work shifts lasting up to 12 hours – who are continually exposed to air pollution, were at greatest risk of potential health impacts. Also, if commuters spent extended periods on train platforms, as many do during service delays, their risk increased.

Air quality is a problem in underground train stations globally, from London to New York and Paris, as tiny particles containing metals such as iron and copper, as well as carbon and mineral oxides generated from wheels, drift down tunnels. Many cities monitor and report on tunnel dust. In Seoul, South Korea they publish live levels of pollution at train stations, and in Britain, where millions are spent cleaning train tunnels, data is published annually.

UNSW environmental epidemiologist Professor Bin Jalaludin believes publishing underground platform pollution levels, as in other countries, would be sensible. “Air pollution in train tunnels has largely been ignored, while road tunnel pollution is widely discussed,” he said. “We give people warnings when entering a road tunnel – wind your windows up and recirculate the air within the car because you don’t want the exhaust coming in while you’re driving. There’s no reason not to apply warnings on train platforms.”

But it does not happen in Sydney. There is no public information about air quality in stations. Staff said there had been no warnings or briefings given to maintenance workers or station officials about air quality, despite the dangers being known. Both Metro and Sydney Trains refused to divulge any details or data about air quality in underground train networks, despite experts warning of potential health impacts for both passengers and workers exposed to underground pollution.

Transport Minister Jo Haylen said she took the Herald’s findings very seriously and has demanded a briefing from bureaucrats. She should act in the public interest immediately. When it comes to air quality, our underground network is a real Wild West with no independent oversight or proper, transparent regulatory regime.

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