Estimated work ability in warm outdoor environments depends on the chosen heat stress assessment metric

Abstract

With a view to occupational effects of climate change, we performed a simulation study on the influence of different heat stress assessment metrics on estimated workability (WA) of labour in warm outdoor environments. Whole-day shifts with varying workloads were simulated using as input meteorological records for the hottest month from four cities with prevailing hot (Dallas, New Delhi) or warm-humid conditions (Managua, Osaka), respectively. In addition, we considered the effects of adaptive strategies like shielding against solar radiation and different work-rest schedules assuming an acclimated person wearing light work clothes (0.6 clo). We assessed WA according to Wet Bulb Globe Temperature (WBGT) by means of an empirical relation of worker performance from field studies (Hothaps), and as allowed work hours using safety threshold limits proposed by the corresponding standards. Using the physiological models Predicted Heat Strain (PHS) and Universal Thermal Climate Index (UTCI)-Fiala, we calculated WA as the percentage of working hours with body core temperature and cumulated sweat loss below standard limits (38 °C and 7.5% of body weight, respectively) recommended by ISO 7933 and below conservative (38 °C; 3%) and liberal (38.2 °C; 7.5%) limits in comparison. ANOVA results showed that the different metrics, workload, time of day and climate type determined the largest part of WA variance. WBGT-based metrics were highly correlated and indicated slightly more constrained WA for moderate workload, but were less restrictive with high workload and for afternoon work hours compared to PHS and UTCI-Fiala. Though PHS showed unrealistic dynamic responses to rest from work compared to UTCI-Fiala, differences in WA assessed by the physiological models largely depended on the applied limit criteria. In conclusion, our study showed that the choice of the heat stress assessment metric impacts notably on the estimated WA. Whereas PHS and UTCI-Fiala can account for cumulative physiological strain imposed by extended work hours when working heavily under high heat stress, the current WBGT standards do not include this. Advanced thermophysiological models might help developing alternatives, where not only modelling details but also the choice of physiological limit criteria will require attention. There is also an urgent need for suitable empirical data relating workplace heat exposure to workability.

A global analysis of heat-related labour productivity losses under climate change—implications for Germany’s foreign trade

“…In the first step, daily 2-m air temperature and nearsurface relative humidity data from the ISIMIP-GCMs is used to estimate daily WBGT values for each grid cell. Subsequently, we calculate work ability changes based on Bröde et al (2017) for two different work environments (indoor and outdoor) utilising a functional relationship between WBGT and three work intensities: light work such as office work, medium work and heavy physical work such as construction work. Finally, we aggregate both present and future work ability levels from grid cell to the model regions used in the CGE model, taking account of different population development pathways for each of the shared socioeconomic pathways (SSP1, SSP2 and SSP3).…”

New approach to identifying proper thresholds for a heat warning system using health risk increments

“…A proper heat-stress indicator in a heat warning system should be related to human physiological changes with negative health impacts; and WBGT as a heatstress indicator has extensive physiological-based evidences (Bernard, 2012). Secondly, WBGT has been used in occupational health as an indicator to prevent heat-stress-related health impacts in workplaces for the past 60 years with a lot of studies demonstrating the relationships between WBGT and heat-related health outcomes (Bernard, 2012;Błażejczyk et al, 2014;Brode et al, 2018;ISO, 2017;Spector and Sheffield, 2014;Yaglou and Minard, 1956). Thirdly, in recent years, increasing research has found that WBGT can be an indicator not only in workplaces (Hyatt et al, 2010;Kakamu et al, 2017;Lin et al, 2012;Sung et al, 2013;Yamamoto et al, 2007).…”

In vitroEvaluation of the Phagocytosis Activity of Neutrophils and Characterization ofStaphylococcus aureusMastitis in Dairy Cows of Small Family Farms

“…Adaptive process in dairy cattle develops metabolic and behavioral physiological compensatory mechanisms to reduce the adverse effects of climate related to the region's racial genotype [52,53]. The risk of suffering thermal stress is increased in the animal population in certain regions with negative effects on livestock production and animal welfare [54,55]. In extreme weather, events with a high ambient temperature, solar radiation, relative humidity and air velocity increase.…”