title: Methods of evaluating protective clothing relative to heat and cold stress: thermal manikin, biomedical modeling, and human testing.
abstract: Personal protective equipment (PPE) refers to clothing and equipment designed to protect individuals from chemical, biological, radiological, nuclear, and explosive hazards. The materials used to provide this protection may exacerbate thermal strain by limiting heat and water vapor transfer. Any new PPE must therefore be evaluated to ensure that it poses no greater thermal strain than the current standard for the same level of hazard protection. This review describes how such evaluations are typically conducted. Comprehensive evaluation of PPE begins with a biophysical assessment of materials using a guarded hot plate to determine the thermal characteristics (thermal resistance and water vapor permeability). These characteristics are then evaluated on a thermal manikin wearing the PPE, since thermal properties may change once the materials have been constructed into a garment. These data may be used in biomedical models to predict thermal strain under a variety of environmental and work conditions. When the biophysical data indicate that the evaporative resistance (ratio of permeability to insulation) is significantly better than the current standard, the PPE is evaluated through human testing in controlled laboratory conditions appropriate for the conditions under which the PPE would be used if fielded. Data from each phase of PPE evaluation are used in predictive models to determine user guidelines, such as maximal work time, work/rest cycles, and fluid intake requirements. By considering thermal stress early in the development process, health hazards related to temperature extremes can be mitigated while maintaining or improving the effectiveness of the PPE for protection from external hazards.
authors.affiliation: Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007, USA. kate.obrien@us.army.mil
authors.forename: Catherine
authors.initials: C
authors.lastname: O'Brien
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Blanchard
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Cadarette
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Endrusick
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Xu
authors.forename: Larry G
authors.initials: LG
authors.lastname: Berglund
authors.forename: Michael N
authors.initials: MN
authors.lastname: Sawka
authors.forename: Reed W
authors.initials: RW
authors.lastname: Hoyt
mesh_terms: D000064:Acclimatization; D001831:Body Temperature; D003080:Cold Temperature; D006358:Hot Temperature; D006801:Humans; D016273:Occupational Exposure / Q000517:prevention & control; D011481:Protective Clothing; D013312:Stress, Physiological