Objectives: (1) To examine the epidemiological characteristics of occupational heat illnesses in South Australia over the past decade, (2) to quantify the association between ambient temperature and occupational heat illnesses, and (3) to investigate the impact of heat waves on occupational heat illnesses.

Methods: Workers' compensation claim data were obtained from SafeWork South Australia for the period of 2001-2010, coded according to the Type of Occurrence Classification System. Weather data were collected from the Bureau of Meteorology. The temperature-heat illness claims association was estimated by using generalized estimating equation models with a piecewise linear function. A case-crossover design was applied to investigate the impact of heat waves on occupational heat illnesses.

Results: There were 306 heat illness claims during the study period, with a claim rate of 4.5 per 100,000. It was a positive relationship between maximum temperature (T_max) and occupational heat illness claims. The overall risk of heat illness was positively associated with T_max, especially when T_maxover threshold 35.5℃. One degree increase of T_max was associated with 12.7% (IRR 1.127, 95% CI 1.067-1.190) increase of heat illness claims. During heat wave periods, the risk of heat illness was between 4 and7 times higher than that of non-heat wave periods.

Conclusions: The results provide a strong scientific evidence to develop or refine heat-related regulations and guidelines to minimize the likely increasing occupational heat stress challenge in a warming climate.