Physiological responses and air consumption during simulated firefighting tasks in a subway system

Area of Science:

• Occupational Health and Safety
• Physiology
• Emergency Response

Background:

• Professional firefighters utilize self-contained breathing apparatus (SCBA) during operations, with cylinder duration often estimated based on nominal capacity.
• The physical demands and physiological strain experienced by firefighters during search and rescue (SAR) operations are critical factors in operational safety and efficiency.

Purpose of the Study:

• To test the hypothesis that air consumption during a simulated subway SAR task exceeds the capacity of a standard 30-minute SCBA cylinder.
• To quantify oxygen uptake, carbon dioxide output, and air consumption rates in firefighters performing a moderate-intensity SAR simulation.

Main Methods:

• 36 professional firefighters (33 men, 3 women) aged 30-53 years performed a simulated subway SAR task.
• Air consumption, oxygen uptake, and carbon dioxide output were measured using a portable breath-by-breath gas exchange analysis system integrated with the SCBA.
• The simulation involved stair descent/ascent, walking, and search and rescue maneuvers.

Main Results:

• The SAR simulation took an average of 12:10 minutes to complete.
• Average oxygen uptake was 24.3 mL kg(-1) min(-1) (47% peak), with a heart rate of 76% of maximum.
• Average air consumption was 51% of the cylinder, with the low-air alarm potentially activating as early as 11 minutes for some individuals.

Conclusions:

• Moderate-intensity SAR tasks impose significant physiological strain on firefighters, leading to higher-than-anticipated air consumption.
• The actual air supply duration from SCBA cylinders may be considerably shorter than the nominal 30-minute rating under such operational conditions.
• Findings suggest a need to re-evaluate SCBA air management strategies and cylinder capacity estimations for moderate-demand firefighting tasks.