This analysis shows that on 24 September 2017, air quality in New South Wales was affected by long-range transport from areas of dust activity in north west NSW, and potentially from smoke and dust activity in the Northern Territory and Western Australia.
September 2017 had record hot weather for that time of year, with below-average soil moisture and reduced groundcover. On 23 September, New South Wales had its warmest September day on record, with extreme temperatures caused by a sequence of troughs that also caused very strong north westerly winds, and a substantial dust event in western NSW. A cold front crossed New South Wales overnight on 23 to 24 September when maximum wind strengths occurred for the 22-24 September episode. Following this, early morning hours on 24 September saw peak PM10 concentrations across many air quality monitoring stations, and 7 Sydney stations exceeded the daily PM10 national benchmark.
This analysis is useful for understanding most non-bushfire-related PM10 pollution days in Sydney and New South Wales generally, when the combination of continental and local dust sources, and conducive weather lead to PM10 levels above the daily national benchmark.