Tunnel air quality is monitored 24 hours a day for all tunnels built after 1997. Roads across NSW make up an extensive network that spans over 25,000 kilometres, including surface roads, tunnels, bridges and underpasses. There are 9 major tunnels within this network that play a key role in relieving surface road congestion. They are equipped with ventilation systems that efficiently disperse tunnel emissions so they have little, if any, impact on air quality.
Since March 2020, operators of all motorway tunnels with ventilation outlets are required to hold an Environment Protection Licence (EPL), and real time air quality monitoring data is made publicly available on each tunnel’s website. The Sydney Harbour Tunnel, built in 1992, is an exception and provides compliance emissions monitoring reports on a 6-monthly basis, which are also published on the tunnel’s website.