Time-series analysis of the incidence trend of heat stress-related disorders in a hot and humid climate in a process industry

Global warming is escalating occupational health risks worldwide, with outdoor workers in hot and humid regions facing disproportionate exposure to extreme heat. In such climates, the synergistic effects of high temperature and humidity critically impair thermoregulation, increasing susceptibility to heat stress-related disorders (HSRDs) a growing concern in low- and middle-income countries where adaptive capacity is limited. This study analyzed the six-year trend (2018-2023) in the HSRDs among outdoor workers in a hot, humid petrochemical industry in southern Iran. This retrospective longitudinal study collected health data on HSRDs alongside concurrent Wet-Bulb Globe Temperature (WBGT) index values. Additive time-series decomposition was used to analyze trends. Analyses were conducted using R and SPSS (p 2 = 0.692). Other specific disorders (e.g., headache, cramp, rash) exhibited unpredictable patterns with high error rates (44% to 147% MAPE). Heat stress exposure is intensifying continuously in these work environments. While the WBGT index trend is predictable, the incidence of specific HSRDs follows complex, unpredictable patterns, making prediction based solely on WBGT challenging. The results underscore the necessity for robust, continuous preventive interventions considering all individual and environmental factors.