ABSTRACT
Researchers from the National Institute for Occupational Safety and Health (NIOSH), in cooperation with mine operators, conducted a study of heat stress exposures among mine rescue workers in underground mines. Mine rescue workers face extreme heat loads as they enter hotand poorly ventilated environments, particularly when they are wearing breathing apparatusesThe burden of wearing a closed-circuit breathingapparatus (CCBA), the inability to drink fluids for extended periods of time, and the potential for ventilation disruptions and fires combineto increase the risk of heat illness during a response to an emergency. In this research, ambient environmental conditions and heat strain indicators were measured using conventional ventilation monitoring tools during mine rescue training exercises. Heat strain was measured with
an ingestible temperature-sensing pill that measured core temperature continuously. In addition, a heart-rate monitoring chest strap was used to indicate physical strain resulting from physical activity and heat. Bothcore temperature and heart rate data were trans-mitted to a remote
recorder worn by a rescuer and time-stamped. Team activities were also observed to determine the contribution of work rate to a person’s total heat load.