Cooling Individuals Using Encapsulating Protective Clothing in a Hot Humid Environment

Abstract

Persons responsible for removing extremely hazardous chemical agents or responding to chemical incidents typically wear fully encapsulating chemical protective ensembles (Level A) during field operations. Level A ensembles are currently used without any ancillary cooling system thereby greatly increasing the risk of thermal injury. The present study evaluated 4 candidate cooling systems intended to mitigate thermal stress experienced by Level A ensemble users in hot humid conditions. Four current members (males, ages = 22-24) of a military chemical response unit served as subjects in this study. Participants wore operationally configured Level A ensembles with a closed circuit soda-lime based re-breather system while performing repeated rest (5 minutes)/work cycles (25 minutes: alternating treadmill walking (4.8 km/hr, 5% grade) and level walking while carrying 22.7 kg) designed to simulate tasks and workloads associated with actual missions for up to 2 hours. Air temperature was maintained at 37 deg C with relative humidity - 75% throughout exposures. Tested cooling systems were: (1) liquid cooled vest with hood (ice cooling source); (2) phase change vest; (3) wetted vest; and (4) liquid cooled whole body garment (super critical air cooling source). The non-cooled Level A configuration served as the experimental control. No significant differences were observed between control and cooling runs. Subjects were unable to complete more than 2 rest work cycles (mean +/- S.D. = 47.9 +/- 8.5 minutes) while experiencing changes in rectal temperature - 1.4 +/- .4 deg C and maximum heart rates - 167 +/- 11 beats/min. Runs terminated either because of breathing difficulties, high heart rates, or subject exhaustion. None of the cooling systems proved effective in overcoming the severe heat stress imposed on subjects.

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 2002
Accession Number
ADP012425

Entities

People

  • Johnathan W. Kaufman

Organizations

  • Naval Air Warfare Center Aircraft Divison

Tags

Communities of Interest

  • Biomedical
  • Human Systems

DTIC Thesaurus Topics

  • Aerial Warfare
  • Air Temperature
  • Aircrafts
  • Body Weight
  • Breathing Apparatus
  • Breathing Gases
  • Chemical Reactions
  • Clothing
  • Compressed Air
  • Data Analysis
  • Data Science
  • Environment
  • Experimental Design
  • Heart Rate
  • Information Science
  • Warfare
  • Workload

Readers

  • Exercise and Sports Science.
  • Systems Analysis and Design
  • Thermal Physics or Thermal Science.