Extreme Heat Arrangements in South Australia: an assessment of trigger temperatures

Abstract

Issue Addressed: The high mortality and morbidity associated with the 2009 heat wave across South Eastern Australia highlighted the need for effective heat-related health promotion and preventive strategies. The adverse health effects of extreme heat are largely preventable, and heat-related health promotion can advise the public about the dangers of hot weather and how to reduce health risks. The South Australian State Emergency Service has outlined a co-ordinated response system in their Extreme Heat Arrangements for South Australia. This paper evaluates the health impacts at the temperature trigger levels incorporated in this plan. Methods: Heat events in Adelaide between 1994 and 2009 were compared in terms of heat duration, heat intensity and their impact on mortality and ambulance call-outs. The health impacts for events meeting specific temperature triggers were estimated. Results: Individual heat events varied in terms of estimated excess mortality and ambulance call-outs. Increased mortality was associated with heat events of 3 or more consecutive days with maximum temperature (Tmax) >= 43°C or average daily temperature (ADT) >= 34°C, while ambulance call-outs increased significantly at lower Tmax levels. The two events reaching the temperature triggers for an extreme heat warning were associated with a 44% (95% CI 26-63%) increase in mortality. Conclusions: The results support the temperature trigger for an extreme heat warning within the Extreme Heat Arrangements for Adelaide, and indicate a limited health impact at lower temperature triggers. Key words: extreme heat, heat-related health promotion, heat action plans.