Recordings of heatwaves date back to the early 1900s and usually are associated with high mortality. In Australia, heatwaves have been the major cause of natural hazard-related deaths. Heatwaves usually do not carry the global media coverage associated with other disasters, and frequently, are referred to as silent disasters. The main impact of heatwaves is on health and human life.

Preliminary results are presented for the 2009 heatwave, investigating the emergency department patient presentations from three public hospitals in Adelaide, a city in the central southern area of Australia.

Demographic and syndromic data were obtained from emergency department records. Ethics permission was obtained prior to data collection. Heatwave conditions occurred from 26 January–07 February 2009. Two non-heatwave periods were day-matched approximately two weeks before and after the heatwave. Data were analyzed by age groups, gender, and ICD codes for chronic conditions.

The two largest groups of people presenting were between 15 and 64 years of age and > 75 years of age during the heatwave and non-heatwave periods. During the heatwave period, both groups had significant increases in patient presentation related to renal problems (ICD 10: N000-N3999) and dehydration and hyperthermia (ICD10: E86, T67). The latter syndrome was far more accentuated during the heatwave, with emergency department patient presentations rising from 2 (non heatwave) to 62 presentations for the 15 and 64 years cohort and from 4 (non heatwave) to 91 for the > 75 years cohort. Cardiovascular- and respiratory-related presentations showed slight increases during the heatwave, while mental health had high presentations for the 15–64 year cohort throughout heatwave and non heatwave periods.

Both young and older people were affected by heatwave, and precautionary warning should be used throughout the community to alert people of the dangers underlying extreme heat conditions.