Oxygen consumption and ventilation during simulated escape from an offshore oil platform.

Twenty-six male workers from the North Sea offshore oil industry took part in a simulated escape exercise at the Offshore Fire Training Centre. The course was 370 m long and had 19.4 m of vertical ascent and descent using the stairs on simulated offshore structures. Inspired ventilation and oxygen consumption were measured using the P. K. Morgan "Oxylog' and subjects breathed through the apparatus by mouthpiece and one-way valve assembly while wearing a nose clip. On comparison with anthropometric data from larger studies, this sample of the offshore work-force was thought to be representative. The mean duration of the exercise period was 371 s (SD = 24 s, range = 325-424 s). Mean oxygen consumption standing still at the start of the trial was 0.421 min-1 (SD = 0.101 min-1, max. = 0.611 min-1) and mean ventilation 12.351 min-1 (SD = 4.251 min-1, max. = 22.271 min-1). During exercise, the mean oxygen consumption rose to 2.711 min-1 (SD = 0.641 min-1, max = 4.051 min-1) and mean ventilation reached 46.341 min-1 (SD = 15.831 min-1, max = 87.361 min-1) during the fifth minute of exercise. At the end of the exercise period, oxygen consumption returned to resting values after 2 min and ventilation after 3 min. There was no indication of an oxygen debt. Oxygen consumption and ventilation were related to body weight and the maximum figures for ventilation and oxygen consumption were seen in individuals of over the 95th centile for weight who completed the exercise more quickly than other subjects. Draft standards for respiratory protective equipment for use during escape from fire do not specify the breathing volumes identified in this study, and which are considerably higher than those being currently considered. Additionally, the atmospheric conditions near a fire are likely to stimulate ventilation to considerably higher levels than those identified here. Accordingly, such equipment is likely to limit physical performance if a similar intensity of exercise is necessary during an escape. The architecture of offshore installations and protocols for escape from them should be structured to minimize exercise, and stair climbing should be avoided if emergency respirators are to be used. Workers should be trained in the use of escape breathing equipment and instruction should include information regarding its limitations and the need to limit exercise to an appropriate level.