WORK IN THE COLD - REVIEW OF METHODS FOR ASSESSMENT OF COLD-EXPOSURE

The obvious hazard of a cold exposure under natural as well as artific ial conditions is tissue cooling and the associated sequel of more or less harmful effects from cold injury to discomfort. The nature, risk and magnitude of effects depend largely on the cooling effect, which r esults from the interaction of climatic factors (air temperature, mean radiant temperature, humidity and wind), protection (clothing) and me tabolic heat production (activity). Assessment of cold stress should b e based on methods which measure or predict this cooling effect in a r elevant and reliable way. The nature of cooling encompasses (1) whole- body cooling, (2) extremity cooling, (3) convective cooling (wind chil l), (4) conductive cooling (contact) and (5) airway-cooling. The revie w contains a description of methods for evaluation of the various type s of cold stress, as well as a discussion of their capacity and limita tions. On the basis of selected methods, recommendations related to lo west permissible temperatures and other measures are discussed and com pared with published data. Apparently, local cooling in most cases pro duces discomfort and harmful effects, before more significant whole-bo dy cooling develops. With strong wind or movement at very low temperat ure, frostnip of unprotected skin may quickly develop. For most other conditions extremity (digit) cooling determines duration of exposure. However, as digit cooling largely depends on whole-body heat balance, it is important to control body cooling by selection and use of approp riate protective clothing.