Health hazard evaluation report: HETA 2000-0065-2899, United States Air Force, Little Rock Air Force Base, Jacksonville, Arkansas.
The National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation (HHE) request from the management of the United States Air Force Institute for Environmental, Safety, and Occupational Risk Analysis (AFIERA), Brooks Air Force Base (AFB), San Antonio, Texas. The request indicated that Air Force personnel working as aircraft fuel systems inspection and repair workers at Little Rock AFB, Jacksonville, Arkansas, were exposed to heat stress, jet fuel, and jet fuel vapors in confined spaces (aircraft fuel tanks). The employees reported experiencing dizziness, lethargy, skin irritation, and a ‘jet-fuel taste’ during and long after exposure to jet fuel. The requesters asked NIOSH to evaluate the heat stress aspects of the employee complaints and make recommendations to prevent heat illness among the employees. The evaluation was part of an on-going collaborative study of Air Force employees’ acute exposure to jet fuel (JP-8), and the other concerns were addressed by this larger study. Data were collected August 21-25, 2000. Individual and task-specific metabolic rates were estimated, and wet bulb globe temperatures (WBGTs) were measured. Heat strain monitoring included core body temperature (CBT) and heart rate (HR) measurements on 21 participants and pre- and post-shift body weight measurements on 9 participants. The sampling results were compared to the NIOSH recommended action limits and recommended exposure limits (RALs/RELs) and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values ( TLVs). NIOSH and ACGIH assess heat stress using sliding scale limits based on environmental (WBGTs) and metabolic heat loads. In addition, ACGIH provides physiological heat strain limits useful for those wearing impermeable personal protective equipment (PPE) and in situations of excess heat stress. For individuals with normal cardiac performance, ACGIH recommends that sustained (over several minutes) heart rate should remain below 180 beats per minute (bpm) minus age (in years), maximum CBT should remain below 100.4F for unselected, unacclimatized personnel (101.3F for medically selected, acclimatized personnel), recovery heart rate at one minute after a peak work effort should be below 110 bpm, and there should be no symptoms of sudden and severe fatigue, nausea, dizziness, or lightheadedness. The results of the evaluation indicated that participants were exposed to heat stress conditions in excess of the NIOSH and ACGIH screening criteria for acclimatized individuals. Nine of twenty-one participants (43%) experienced heat strain signs (HR and/or CBT in excess of the ACGIH criteria). In addition, one of nine participants weighed before and after work activities was dehydrated (lost enough weight to exceed the ACGIH recommendation that body weight loss over a shift not exceed 1.5%) and another five participants developed mild dehydration (body weight change of -1.5% or less). The evaluation results combined with the potential for heat strain to increase as temperatures rise during the summer indicate that FSM personnel should continue to be included in a heat stress management program. In addition, affected participants were not aware of having developed heat strain, indicating a need for a physiological self-monitoring program to be added to the heat stress program. During the NIOSH evaluation, health hazards from environmental conditions and overwork existed for fuel cell maintenance and other workers, and 9 of 21 participants developed heat strain as indicated by the physiological monitoring results (CBTs and/or heart rate levels were in excess of occupational criteria). Of the nine participants who were weighed pre- and post-shift, 5 developed mild dehydration and one exceeded the ACGIH recommendation that body weight loss over a shift not exceed 1.5%, indicating a greater risk for developing heat-related illnesses. Little Rock AFB has a heat stress instruction, however the instruction does not include a system for physiological monitoring. Recommendations are made to implement physiological (heat strain) monitoring and to take WBGT measurements in or around immediate work areas at least hourly during the hottest parts of the shift and the hottest months of the year.
Region-6; Hazard-confirmed; Heart-rate; Heat; Heat-exposure; Heat-stress; Aircraft; Aircrews; Military-personnel; Confined-spaces; Physiological-effects; Physiological-measurements; Physiological-testing; Jet-engine-fuels; Jets; Maintenance-workers; Exposure-levels; Exposure-limits; Metabolic-rate; Body-fluids; Body-temperature; Body-weight; Temperature-effects; Hazard-Confirmed