These were the 7 hottest days of the study Multivariate analysis of personal variables (e.g. P60 appears to be determinate criteriaġ3 Results (cont) Percentage of workers exhibiting heat strain increased quickly between oC WBGT All cases of heat strain were found to be clustered in 7 of 13 days studied. Hourly core temperature >38oC on more than 2 occasions OR Hourly 60 second recovery pulse rate (P60) >110 beats/minute on more than 2 occasions OR Hourly 180 second recovery pulse rate (P180) >100 beats/minute on more than 2 occasions This is the criteria that was used to assess heat strain in the project.ġ2 Results Air temperatures ranged from 20oC in the mornings to >30oC in afternoons with some afternoons >40oC Mean WBGT of last 4 hours of measurements in day (afternoon when air temperature highest) ranged from 16.1oC to 29oC Rectal temperature & recovery pulse rate increased during the day. Rectal temperature (Tc) Recovery pulse (P60 seconds & P180 seconds) Daily sweat loss It is understood (but could not be confirmed) that rectal thermometers were used.Īge of individual workers Body fat Number of days worked in previous week Alcohol intake the previous night Percentage dehydrationġ1 Criteria For Heat Strain Used in Study Hourly measurements were made of the thermal environment Simultaneous hourly measurements made of physiological variablesĪir temperature Radiant temperature Humidity Air speed Insulation value of clothing Metabolic load Shearers are paid on a per sheep basis and thus rest breaks are limited.ħ The Study Carried out over 13 working days & consisted of 60 persons The work environment is typically a tin shed with no air-conditioning. A single shearer will shear several hundred sheep per day This case study is based in part on a research project conducted in an arid climate in the 1980’s. Case Studies (hot environments) Discuss various case studies to highlight various aspects of hot environments Evaluation & Control of Cold Environments Understand the principles by with thermal stress in cold environments can be evaluated Review the approaches to controlling worker exposure to thermal stress in cold environmentsĪpproaches to Risk Assessment Review approaches adopted in various parts of the world Case Studies (cold environments) Discuss various case studies to highlight various aspects of cold environmentsĥ Heat Stress & Heat Strain during Sheep ShearingĬase Study 3 Heat Stress & Heat Strain during Sheep Shearing Derived from : Dr R Gun AIOH Conference 1987Ħ The Situation Large part of world wool industry is based on sheep properties in arid regions Sheep are shorn in late summer when temperatures are frequently 40oC Work is physically demanding and shearers are paid by number of sheep shorn per day.
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