A Guide to Managing Heat Stress

Description

This 2013 guideline document presents thermal stress guidance that has been developed for the Australian environment. The aim of the document is to provide an emphasis on guidance rather than the establishment of a formal standard. This guidance is not intended to be a definitive document on the subject of heat stress but will provide enough information and further references for employees and employers to manage heat stress in the4 Australian workplace. In the first part, this guidance document provides a brief summary of the approach for non-technical backgrounds. The second part is a more comprehensive description leading to a single location for those needing to assess and manage heat on the work place. Contents Provides some definitions around heat stress and describes a three-step approach for managing it. The first step is risk assessment, which uses a flow chart to allow users to easily follow the process to establish which one of three levels of assessment is required: qualitative risk assessment using known parameters such as PPE (Level 1); semi-quantitative risk assessment using ambient data (Level 2); or quantitative risk assessment using personal physiological data (Level 3). Detail is provided on the types of semi-quantitative analyses that can take place, discussing in particular, the following methods: Predictive Heat Strain; Thermal Work Limit; or the Wet Bulb Globe Temperature index. Further detail is provided on the types of quantitative, Level 3 analyses that can assess heat strain. Following on from the assessments this Guidance document indicates the comparison criteria that can be used to determine the level of risk and, subsequently, the heat stress management and controls that can be used to mitigate the identified risks. This document includes: a bibliography for additional research and resources; a basic thermal risk assessment that can be used to ascertain an individual’s potential to experience a thermal strain event; information on how the body manages heat; heat related illnesses and injuries; physiological factors that contribute to heat illness, including acclimatisation; using urine, core temperature and heart rate as a measure of heat illness; examples of the hierarchy of controls for managing in thermal stressors in the workplace. Contents Preface A Guide to Managing Heat Stress Section 1: Risk assessment (the three step approach). Section 2: Screening for clothing that does not allow air and water vapour movement. Section 3: Level 2 assessment using detailed analysis. Section 4: Level 3 assessment of heat strain. Section 5: Occupational Exposure Limits Section 6: Heat stress management and controls Table 2: Physiological Guidelines for Limiting Heat Strain HAZARD TYPE Assessment Point Value Assessment Point Value Milk Bibliography Appendix 1 - Basic Thermal Risk Assessment using Apparent Temperature Appendix 2 – Table 5: Apparent Temperature Dry Bulb/Humidity scale. Documentation of the Heat Stress Guide Developed for Use in the Australian Environment 1.0 Introduction 1.1 Heat Illness – A Problem Throughout the Ages. 1.2 Heat and the Human Body 2.0 Heat Related Illnesses 2.1 Acute Illnesses 2.1.1 Heat Stroke 2.1.2 Heat Exhaustion 2.1.3 Heat Syncope (Fainting) 2.1.4 Heat Cramps 2.1.5 Prickly Heat (Heat Rash) 2.2 Chronic Illness 2.3 Related Hazards 3.0 Contact Injuries 4.0 Key Physiological Factors Contributing to Heat Illness 4.1 Fluid Intake 4.2 Urine Specific Gravity 4.3 Heat Acclimatisation 4.4 Physical Fitness 4.5 Other Considerations in Reducing Exposure in Heat-Stress Conditions 5.0 Assessment Protocol 6.0 Work Environment Monitoring and Assessment 6.1 Risk Assessment 6.2 The Three Stage Approach 6.2.1 Level 1 Assessment: A Basic Thermal Risk Assessment 6.3 Stage 2 of Assessment Protocol: Use of Rational Indices 6.3.1 Predicted Heat Strain (PHS) 6.3.2 Thermal Work Limit (TWL) 6.3.3 Other Indices 6.3.3.1 WBGT 6.3.3.2 Basic Effective Temperature 7.0 Physiological Monitoring - Stage 3 of Assessment Protocol 7.1 Core Temperature 7.2 Heart Rate Measurements 8.0 Controls 8.1. Ventilation 8.2 Radiant Heat 8.3 Administrative Controls 8.3.1 Training 8.3.2 Self-Assessment 8.3.3 Fluid Replacement 8.3.4 Rescheduling of Work 8.3.5 Work/Rest Regimes 8.3.6 Clothing 8.3.7 Pre-placement Health Assessment 8.4 Personal Protective Equipment 8.4.1 Air Cooling System 8.4.2 Liquid Circulating Systems 8.4.3 Ice Cooling Systems 8.4.4 Reflective Clothing 9.0 Bibliography Appendix A: Heat Stress Risk Assessment Checklist Appendix B: Preliminary Plant Heat Stress Risk Assessment Sheet Appendix C: Thermal Measurement Appendix D: Encapsulating Suits