Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August–1 September 2010: Climate Change and Environmental Health
Two extreme heatwaves occurred in South Australia in 2008 and 2009. It is of interest how these 2 unprecedented heatwaves compare to averaged heatwave risks preceding these events. Dose-response effects of duration (increasing number of days within a heatwave) and intensity (by increments of 1°C above 35°C) of heatwaves (1993–2008) were also examined. Weather-based heatwave triggers were explored to inform relevance of current intervention measures.
Using case-series analysis, daily morbidity and mortality rates during heatwaves were compared with rates during non-heatwave periods within the respective years and restricted to the warm season (October–March). Health outcomes examined were total, age group and disease-specific hospital admissions, emergency presentations, ambulance call-outs, and mortality. Heatwave definition was maximum temperature ≥35°C for 3 or more days.
Ambulance call-outs during the 2 extreme heat events significantly exceeded call-outs from averaged preceding heatwaves affecting mainly cardiac and neurologically related call-outs. Only small increases in total hospital and emergency visits were observed. Renal admissions were increased substantially in both clinical settings, particularly in the older age groups. Direct heat-related admissions increased 14-fold for hospital admissions and 12-fold for emergency presentations in 2009 compared to 3-fold during averaged heatwaves. Increases in total mortality were restricted to the 2009 heatwave (10%; 95% CI: 0.99–1.22; P = 0.09). The major impact occurred in the 15–64 yrs age group, where mortality increased by 37% (95% CI: 1.09–1.71; P = 0.01). Older age groups were not affected. Significant dose-response relationships were observed for duration (ambulance, hospital and emergency setting) and for intensity (ambulance and mortality). Mortality started to increase at average temperature 31°C (average of daily maximum and minimum; 3 or more days).
These findings indicate a higher level of health risk during the recent severe heatwaves in Adelaide than in previous heatwaves. Evaluation of health outcomes in relation to relevant thresholds will guide future community interventions.