Future projections of labor hours based on WBGT for Tokyo and Osaka, Japan, using multi-period ensemble dynamical downscale simulations

Abstract

Following the heatstroke prevention guideline by the Ministry of Health, Labor, and Welfare of Japan, "safe hours" for heavy and light labor are estimated based on hourly wet-bulb globe temperature (WBGT) obtained from the three-member ensemble multi-period (the 2000s, 2030s, 2050s, 2070s, and 2090s) climate projections using dynamical downscaling approach. Our target cities are Tokyo and Osaka, Japan. The results show that most of the current climate daytime hours are "light labor safe,", but these hours are projected to decrease by 30-40% by the end of the twenty-first century. A 60-80% reduction is projected for heavy labor hours, resulting in less than 2 hours available for safe performance of heavy labor. The number of "heavy labor restricted days" (days with minimum daytime WBGT exceeding the safe level threshold for heavy labor) is projected to increase from ~5 days in the 2000s to nearly two-thirds of the days in August in the 2090s.

Comparative evaluation of human heat stress indices on selected hospital admissions in Sydney, Australia

“…51 Projection of heat-health impacts has mostly focussed on daily maximum temperature 10,52,53 or mean temperature, 33,54,55 while heat-humidity and heatwave indices have occasionally been used. 23,56 This analysis suggests that maximum sWBGT may be a good point of comparison for future projection work. Simple temperature statistics may be a better fit in some cases, especially since mean temperature is already in wide use, but this depends on the health response projected.…”

“…Heat‐humidity indices generally display similar uncertainty to temperature indices when projecting into the future despite the additional input, because global temperature and humidity are not independent 51 . Projection of heat‐health impacts has mostly focussed on daily maximum temperature 10,52,53 or mean temperature, 33,54,55 while heat‐humidity and heatwave indices have occasionally been used 23,56 . This analysis suggests that maximum sWBGT may be a good point of comparison for future projection work.…”

“…Heat‐humidity indices quantify this effect by combining temperature, humidity and other weather observations. Two heat‐humidity indices—Simplified Wet Bulb Globe Temperature (sWBGT) 19 and Apparent Temperature (AT) 20 —are popular in Australia with both the public and researchers 11,21–23 …”

“…Two heat-humidity indices-Simplified Wet Bulb Globe Temperature (sWBGT) 19 and Apparent Temperature (AT) 20 -are popular in Australia with both the public and researchers. 11,[21][22][23] Heatwave indices, in contrast, are rolling functions of temperature alone. Duration of heat stress exposure partly determines the severity of heat stroke, 4 but repeated exposures on longer timescales trigger physiological adaptations.…”

The effect of hot days on occupational heat stress in the manufacturing industry: implications for workers’ well-being and productivity

“…Heat stress, as a consequence of global warming, is projected to monotonically increase throughout the twenty-first century in many regions of the world (Fischer and Schär 2010; Fischer et al 2012; Pal and Eltahir 2015; Suzuki-Parker and Kusaka 2016). Under certain conditions, such as manual labor during heat waves, the capacity of the human body to dissipate adequate heat may be anticipated on a regular basis in certain parts of the world during this century (Smith et al 2014).…”