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

Abstract

Climate change is expected to exacerbate heat stress at the workplace in temperate regions, such as Slovenia. It is therefore of paramount importance to study present and future summer heat conditions and analyze the impact of heat on workers. A set of climate indices based on summer mean (Tmean) and maximum (Tmax) air temperatures, such as the number of hot days (HD: Tmax above 30 °C), and Wet Bulb Globe Temperature (WBGT) were used to account for heat conditions in Slovenia at six locations in the period 1981-2010. Observed trends (1961-2011) of Tmean and Tmax in July were positive, being larger in the eastern part of the country. Climate change projections showed an increase up to 4.5 °C for mean temperature and 35 days for HD by the end of the twenty-first century under the high emission scenario. The increase in WBGT was smaller, although sufficiently high to increase the frequency of days with a high risk of heat stress up to an average of a third of the summer days. A case study performed at a Slovenian automobile parts manufacturing plant revealed non-optimal working conditions during summer 2016 (WBGT mainly between 20 and 25 °C). A survey conducted on 400 workers revealed that 96% perceived the temperature conditions as unsuitable, and 56% experienced headaches and fatigue. Given these conditions and climate change projections, the escalating problem of heat is worrisome. The European Commission initiated a program of research within the Horizon 2020 program to develop a heat warning system for European workers and employers, which will incorporate case-specific solutions to mitigate heat stress.

Keywords: Climate change; Heat stress; Hot day; Occupational health; Wet Bulb Globe Temperature.

Fig. 1

Maps showing the spatial distribution of 30-year (1981–2010) mean summer temperature (a), 30-year (1981–2010) mean maximum temperature of the hottest month (July) (b), 51-year (1961–2011) long-term trend (per decade) of mean summer temperature (c), and 51-year (1961–2011) long-term trend (per decade) of mean maximum temperature of the hottest month (d)

Fig. 2

Spatial distribution of temperature- and WBGT-derived indices (see Table 1) as represented by the observations for the period 1981–2010 (first column). Climate change signal for the period 2070–2099 with respect to 1981–2010 for three RCPs (second to fourth columns). Each panel represents the multi-model ensemble median of the index and the number of RCM simulations contributing to the multi-model ensemble median is depicted in brackets

Fig. 3

Climate change signal for some temperature- and WBGT-derived indices (rows) for six Slovene stations (columns). The boxes show the full uncertainty range across models for each RCP. The number of RCM simulations contributing to the multi-model ensemble median is depicted in brackets

Fig. 4

Top left panel: Monthly boxplots for daily values of in shade WBGT at Celje station for the period 1981–2015. Top right panel: Monthly boxplots for daily values of in shade WBGT at Celje station for the year 2016. Middle panel: Air temperature and indoor (1.5 m height) WBGT (every half hour) at the injection molding workplace in the odelo factory in July 2016. Bottom panel: Air temperature and in shade WBGT (every half hour) in Celje in July 2016

Fig. 5

Survey conducted on workers in the odelo factory. Top left panel: How do you perceive the workplace temperature during heat waves? Top right panel: How comfortable are your clothes during heat waves? Middle left panel: Have you noticed that you have been increasingly more exposed to heat stress than in the past? Middle right panel: Is the situation regarding temperature during summer worse at home/on the way than at your workplace? Bottom left panel: Which of these heat stress symptoms do you face during work in summer? Bottom right panel: Have you ever been affected by any of these health problems at work during a heat wave?