Human heat stress

163 Pages·2019·2.963 MB·English

by  Parsons, Kenneth C

Human Heat Stress

Human Heat Stress
Ken Parsons
CRC Press
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Library of Congress Cataloging-in-Publication Data
Names: Parsons, K. C. (Kenneth C.), 1953- author.
Title: Human heat stress / Ken Parsons.
Description: Boca Raton, FL : CRC Press/Taylor & Francis Group, 2019. |
Includes bibliographical references and index.
Identifiers: LCCN 2018050354 | ISBN 9780367002336 (hardback : acid-free
paper) |
ISBN 9780429020834 (ebook)
Subjects: LCSH: Heat exhaustion. | Heat--Physiological effect.
Classification: LCC RC87.1 .P36 2019 | DDC 616.9/89--dc23
LC record available at https://lccn.loc.gov/2018050354
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Contents
Preface xi
Author xv
1 Human Heat Stress 1
Human Heat Stress 1
The Human Disposition 2
The Body Heat Equation 4
The Six Basic Parameters 5
Body Heat Transfer by Convection 6
Body Heat Transfer by Radiation 6
Body Heat Transfer by Evaporation 8
Regulating Body Temperature and Comfort—Human
Thermoregulation 9
Feeling Hot 10
2 Thermoregulation and Human Response to Heat 13
The Hot Environment 13
Human Thermoregulation 14
Physiological Thermoregulation 15
Heat Detection 16
Central Processing 17
Human Physiological Response 18
Blood Flow 18
Sweating 19
Acclimatization 20
Behavioral Acclimatization 23
3 Human Metabolic Heat 25
Body Heat 25
Units 26
Measurement and Estimation of Metabolic Rate 27
Whole Body Calorimetry 27
Indirect Calorimetry 28
Average Metabolic Rate of a Group 30
vii
viii Contents
Estimation of Metabolic Rate from Heart Rate 31
Estimation of Metabolic Rate Using Databases and Tables 32
ISO 8996 (2004) Ergonomics of the Thermal
Environment—Determination of Metabolic Rate 32
Metabolic Rate in Load Carriage 33
Subjective Methods 34
Clothing and Metabolic Rate 34
Different Populations and Vulnerable People Including
People with Disabilities 34
4 Human Heat Stress and Clothing 37
Clothing Restricts Heat Transfer 37
The Thermal Properties of Clothing 38
Vapor Permeability of Clothing 40
Clothing Ventilation 41
Measurement of the Dry Thermal Insulation of Clothing 41
Measurement of Clothing Vapor Permeation, Ventilation, and
Pumping 42
Measurement and Assessment of the Thermal Properties of
Clothing Using Human Subjects 42
Heat Strain in Protective Clothing and Equipment 44
Smart Clothing 44
Clothing and Behavioral Thermoregulation 45
ISO 9920 (2007) (Corrected 2008): Ergonomics of the
Thermal Environment—Estimation of Thermal Insulation
and Water Vapor Resistance of a Clothing Ensemble 46
5 Measurement of Heat Stress 47
The Six Parameters 47
Air Temperature (T ) 47
A
Mean Radiant Temperature (T ) 48
R
Solar Radiation 49
Air Velocity (v) 50
Humidity (ϕ) 50
The Psychrometric Chart 51
Natural Wet-Bulb Temperature (T ) 52
NW
Operative Temperature (T ) 53
O
The Heat Stress Index 53
6 Measurement of Heat Strain 57
Physiological Indicators of Heat Strain 57
Internal Body Temperature 57
Contents ix
Skin Temperature 58
Heart Rate 59
Sweating—Body Mass Loss 60
Personal Monitoring Systems 61
Psychological Measures 61
7 Assessment of Heat Stress Using the WBGT Index 63
The Wet-Bulb Globe Temperature Index 63
Avoiding Heat Casualties in the U.S. Marine Corps 65
ISO 7243 (2017): Ergonomics of the Thermal Environment—
Assessment of Heat Stress Using the WBGT Index 67
Global Warming, Heat Stress, the WBGT, and Productivity 70
National Institute for Occupational Safety and Health (NIOSH)
2016 Revised Criteria for Occupational Exposure to Heat and
Hot Environments 71
WBGT Limits in Sport 72
8 Assessment of Heat Stress Using the Body Heat Equation 75
Evaporation Required for Heat Balance 75
ISO 7933 (2004): Ergonomics of the Thermal Environment—
Analytical Determination and Interpretation of Heat Stress
Using Calculation of the PHS 78
ISO 7933 (2004) Computer Program 79
ISO DIS 7933 (2018) 80
9 Computer Models for Assessing Human Heat Stress 83
Human Models and Heat Stress 83
Computer Models of Human Thermoregulation 84
The Stolwijk and Hardy Model 84
The 2-Node Model of Human Thermoregulation 85
The Passive System, Inputs, and a Thermoneutral Start 86
The Thermoregulatory Controller 87
Timers to Plot Variations in Body Condition with Time 88
Gagge’s 2-Node Model—The Computer Program 88
Outputs 91
Other Thermal Models 93
Thermal Models and Heat Stress Indices 94
10 Human Heat Illness and Prevention 97
Heat Illness Mostly Affects the Vulnerable and the Sporty 97
Temperature Regulation Heatstroke 98
Heat Syncope 99