What question did this study set out to answer?

This study aims to assess the trend of heat stress-related disorders among outdoor workers in a hot, humid environment over six years.

April 23, 2026Open Access

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

Key Points

This study aims to assess the trend of heat stress-related disorders among outdoor workers in a hot, humid environment over six years.
Conducted a retrospective longitudinal analysis of health data from 2018 to 2023.
Utilized the Wet-Bulb Globe Temperature (WBGT) index for environmental data analysis.
Applied additive time-series decomposition using R and SPSS to evaluate trends.
The mean WBGT index significantly increased from 27.73 to 29.75 °C over the study period.
Critical heat stress levels among workers rose to approximately 55% during summer months.
Only general heat-related disorders displayed relatively accurate predictive modeling with R² = 0.692.

Abstract

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.

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