International standard ISO 7243 (1989-08-01). Hot environments-estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature = Norme internationale ISO 7246 (1989-08-01). Ambiances chaudes-estimation de la contrainte thermique de l'homme au travail, basee sur l'indice WBGT (temperature humide et de globe noir) (International Organization for Standardization, 1989)