An extensive ozone pollution episode during 10 to 11 February 2017 impacted NSW coastal regions in the Illawarra, Sydney, Central Coast and Newcastle. This occurred during a severe, four-day heat wave when a slow-moving high-pressure system over New South Wales provided hot and calm conditions conducive to the formation and build-up of photochemical ozone. The maximum temperatures in Sydney reached 45°C during this period. The hot and light north-westerly synoptic flows interacting with afternoon north-easterly sea breezes, determined the spatial extent, location and duration of elevated ozone in the impacted regions.
This episode reflects the combined impact of local scale (sea breezes) and synoptic meteorological conditions that typically lead to elevated ozone pollution in Sydney, and broadly across the NSW Greater Metropolitan Region.