Validation Fire Fighter suit 2007

Purpose : Too often fire fighters develop burns or get overheated during fire fighting. To improve the quality of care, a fire fighter suit was developed in which burns and overheating may be anticipated by monitoring heart rate and predicted skin temperature. Physiological measurements are taken and sent to a mobile computer for processing. The purpose of this experiment is to validate the calculated physiological strain.
Methods : Twelve fit male subjects performed a test battery consisting of walking/running with and without carrying two roll frames of hose in the hands, lifting, jumping, crawling, hose rolling, opening and closing cans, dummy dragging and ladder climbing in normal environmental circumstances (20 ºC, 55% relative humidity), while wearing the new fire fighter suit 2007. Some of the test elements came from the EN-469. Heart rate (HR) measured by wrist cuffs was compared with validated HR measurements. Temperature (in the inner jacket and in the outer jacket), the heat flux in the jacket and the humidity in the jacket (either by weighing the jacket or with the use of extra sensors) were measured to assess the usefulness of these parameters to predict skin temperature.
Results : HR measurements using the cuffs were shown not to be valid. The HR measurements revealed a dependency on the participant and an inability to exclude all artefacts interfering with the signal. Microclimate temperatures, relative humidity and heat flux sensors predict skin temperature with a range up to 0.5 ºC in a neutral environment. Less parameters increases inaccuracy in the predicted skin temperature.
Some of the test elements of the EN-469 were too strenuous for our subjects; some tests require specific skills or equipment. The head and belly/ chest were rated the warmest and sweatiest while the feet and legs were rated the coolest and least sweaty.
Conclusions : The fire fighter suit 2007 is not yet valid enough to be used as a monitoring tool for fire fighters during fire fighting tasks. The HR measurements revealed a participant dependent inability to exclude all artefacts interfering with the signal. The accuracy of skin temperature prediction might be good enough but the prediction should also be investigated in a hot climate. The prediction requires all three of temperature, humidity and heat flux measurements in the jacket. The measurement system itself needs to be better shock and bump proof to ensure undisturbed measurement.
The EN-469 test battery can only be used in test conditions with fit fire fighters.
The subjective measurements reveal that when a part of the body is rated very warm, that part of the body is rated high on sweat rate as well.