AGGRESSIVE WATER FOG ATTACK REDUCES HEAT STRAIN DURING SHIPBOARD FIREFIGHTING1182

Abstract

This study compared the use of two shipboard firefighting water attack methods, direct straight-stream (DIR) and aggressive fog (FOG), on heat strain of naval firefighting personnel. Eight males and four females aged 31 ± 4 yrs served as subjects. Portable data logger recordings were made of heart rate (HR), and rectal (Tre), chest (Tch), arm (Tar), hand(Tha), index finger (Tfi), thigh (Tth), foot(Tfo), and big toe (Tto) temperatures during altematingly ordered DIR and FOG tests. Subjects wore cotton work clothes underneath the standard Navy firefighting ensemble plus oxygen breathing apparatus. Fire compartment temperatures at the time of entry averaged (±SD) 591± 43°C. Firefighters entered into the fire compartment 1.2 to 1.8 m, took a crouched position, and set the nozzle angle to either 60° for FOG or 30° for DIR. During both FOG and DIR, water was discharged in a series of 2 or 3 short bursts lasting 2-3 sec in duration. During pre-activities and actual firefighting, HR and all body temperatures increased progressively. Time to extinction of flames was significantly (p<.05) less for FOG (9.1 ± 0.6 min) compared to DIR (10.9 ± 0.6 min). Analysis of covariance (adjusted for pre-entry values) showed no differences for Tha ([horizontal bar over]X=38.2°C), Tfi ([horizontal bar over]X=41.6°C), and Tth ([horizontal bar over]Xs=38.2°C). However, FOG Tre ([horizontal bar over]X=38.2°C), Tch([horizontal bar over]X=39.6°C), Tar ([horizontal bar over]X=40.0°C) and Tfo ([horizontal bar over]X=36.0°C) were lower (p<.05) compared to DIR (38.5°C, 40.4°C, 41.0°C, 37.4°C, respectively). HR for FOG ([horizontal bar over]X=185 bpm) was also lower (p<.05) than DIR ([horizontal bar over]X=171 bpm). Our findings suggest that use of the FOG attack method reduces heat strain in personnel conducting shipboard firefighting.