The impact of heat on occupational injuries, illnesses and associated economic costs in Australia

Abstract

Introduction: High temperatures have been associated with increased morbidity and impaired labor productivity in workers. Despite extensive relevant literature, there is limited understanding of the associated economic impact. This PhD aimed to analyse economic burden secondary to occupational heat stress and create an Australian national cost profile of heat-attributable occupational injuries and illnesses (OIIs) within Australia. Literature review: Estimated retrospective and future heat-attributable occupational economic burdens are substantial. Predicted global costs from lost worktime were US$607 billion annually from 2001-2020. This was projected to US$1,069, US$1,626, and $3,286 billion worldwide following a 1, 2, and 4!C increase in global average temperature. In Australia from 2013-2014, annual costs of US$6.2 (95% CI: 5.2 7.3) billion were estimated, 0.33% 0.47% of Australia’s GDP. Estimated annual heat-related expenses from occupational injuries exceeded US$1 million in Spain and Guangzhou, China and US$250,000 in Adelaide, Australia. Low- and middle-income countries and countries with warmer climates had greater losses as a proportion of GDP. Methodology: Climate and workers’ compensation claims data were extracted representing OIIs from July 2005 to June 2018 in seven Australian capital cities: Adelaide, Brisbane, Darwin, Hobart, Melbourne, Perth, and Sydney. Daily maximum wet bulb globe temperature was used to measure the impact of temperatures above and below the mean. The Excess Heat Factor was used to define the presence, intensity, and duration of heatwaves. OIIs and associated costs were estimated separately per city with time series, distributed lag non-linear models and modelled using (quasi-)Poisson and Tweedie distributions, respectively. City-level estimates were pooled together with multivariate meta-analysis. Heatwave-attributable risks were projected to the 2030s and 2050s under RCP4.5 and RCP8.5. Temperature-attributable OIIs: Heat-attributable and cold-preventable fractions of OIIs were 1.66% (95% eCI: 1.38-1.94) and 0.66% (95% eCI: 0.45-0.89%), respectively. These represented 38,540 heat-attributable OIIs and 15,409 coldpreventable OIIs. 1.53% (95% eCI: 0.77-2.27%) and 1.33% (95% eCI: 0.66-1.97%) of costs were heat- and cold-attributable, respectively, with increased costs per OII during cold despite fewer OIIs. The associated financial burdens were AU$651 and AU$574 million, representing AU$94 million annually and AU$88.1 and AU$76.3 per worker, respectively. Heatwave-attributable OIIs: 0.13% of OIIs (95%eCI: 0.11-0.16%) were heatwaveattributable, equivalent to 120 OIIs annually. These were associated with 0.25% of heatwave-attributable costs (95%eCI: 0.18-0.34%), equal to AU$4.3 million annually. By 2050, 0.17% (95%eCI: 0.10-0.27%) and 0.23% (95%eCI: 0.13-0.37%) of OIIs were heatwave-attributable under RCP4.5 and RCP8.5, respectively. Projected costs estimates under RCP4.5 and RCP8.5 were 0.13% (95%eCI: -0.27-0.46%) and 0.04% (95%eCI: -0.66-0.60), with significant associations observed with extreme heatwaves in 2030 (0.04%, 95%eCI: 0.02-0.06%) and 0.04% (95%eCI: 0.01-0.07), respectively. Attributable fractions were similar to baseline when assuming theoretical 100% climate adaptation. Implications: OIIs and associated costs increase with both moderate and extreme heat. This morbidity and financial burden is substantial. Expenses are likely to be less than the costs secondary to labor productivity loss not associated with OIIs. Collectively, however, they portray a more detailed estimate of the economic impact secondary to heat in the workplace. Climate adaptation and mitigation are imperative to minimize future morbidity and costs.