Long-term research into Sydney air quality suggests most people in region are exposed to air pollution at levels considered unsafe by the WHO

Air pollution in New South Wales is estimated to cause 603 premature deaths and increase health costs by $4.8bn each year, according to a long-term government study.

Published online the day before the Perrottet government went into caretaker mode ahead of this month’s state election, the Sydney air quality study suggests most people in the city’s greater metropolitan region are exposed to air pollution at levels considered unsafe by the World Health Organization.