Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain (ISO 7933:2023)

This document establishes the methodology for analyzing and interpreting heat stress in occupational environments where individuals are exposed to heat. It provides a framework for predicting the physiological strain resulting from thermal exposure based on environmental factors and individual characteristics. The approach enables the assessment of heat strain by utilizing the human body's heat balance equation, incorporating parameters such as air temperature, humidity, airflow, radiation, clothing insulation, and work rate. By applying the specified calculation procedures, professionals can estimate critical physiological responses, including core body temperature and skin wettedness, to determine the level of heat strain. The method is applicable across diverse settings, including industrial workplaces and other scenarios involving thermal stress. It offers a standardized procedure to evaluate whether existing conditions may lead to excessive strain and supports decision-making for heat risk management. The approach emphasizes predictive modeling to anticipate physiological responses before they occur, facilitating proactive measures to protect worker health and safety in hot environments.