Heatwaves and occupational injuries and illnesses risk varied at localised spatial scale: A national study in Australia

• 5.1 % to 29 % risk of occupational injuries and illnesses is due to Heatwaves in Australian cities. • Workers located in the outer urban areas face a heightened risk of heat-related occupational injuries. • Heat-attributable fraction of OI increases up to 0.85 % in high-emission scenarios by mid-century. • Our findings inform location-specific policies for local governments to protect workers from heat impacts. Heatwaves (HWs) pose significant risks to occupational safety in Australia, particularly for workers in roles requiring prolonged heat exposure. This study, for the first time, addresses critical gaps in the existing literature by examining the impact of HWs on occupational injuries and illnesses (OI) at a fine spatial scale and projecting future OI burdens under climate change scenarios. Using time series study design and distributed lag nonlinear models we establish the association between HWs, assessed via the Excess Heat Factor (EHF), and OI in Adelaide, Brisbane, Melbourne, and Sydney at the Statistical Area Level 3 (SA3). The study reveals a substantial cumulative OI risk ranging between 5.1 and 29.0 % during heatwaves, with outer peripheries and rapidly urbanizing peri -urban areas showing heightened vulnerability. Younger workers, males, injury-related claims, and workers in areas with higher temperatures and less vegetation were identified as particularly susceptible to HWs. By utilising high-resolution geospatial data and future projections, our study provides new insights into the spatial heterogeneity of HW impacts on OI within cities, a previously underexplored area of research. Projected HW impacts indicate a potential increase in HW-related attributable fractions (AF) of OI, for example, in Greater Sydney, where the overall OI AF is projected to rise from 0.89 % to 1.64 % under high-emission climate scenarios. These findings emphasise the importance of developing localized, climate-related adaptation and intervention strategies to safeguard workers and reduce both the disease burden and associated economic costs and productivity loss.