Thermal Work Environments – Part 1: An Introduction to Biometeorology and Job Design

     In the minds of many readers, the term “thermal environment” may induce images of a desert, the Arctic, or other thoughts of extreme conditions.  While extreme conditions require intense planning and preparation, they merely bookend the range of work conditions that require consideration.  That is to say that the environmental conditions of all workplaces should be thoroughly assessed and the impacts on the people within them properly addressed.
     The ensuing discussion is generalized to be applicable to a wide range of activities.  The information presented in this series is intended to be universally applicable in manufacturing and service industries.  Additional guidance may be available from other sources; readers should consult industry- or activity-specific organizations for detailed information on best practices and regulations that are beyond the scope of this series.

Terms in Use
     Most of the terms used in this series are in common use, though their application to the subject at hand may be unfamiliar to some readers.  The usage of some of these terms is presented here to facilitate comprehension of information throughout the series.
     It seems logical to begin with the title of the series:  “Thermal Work Environments.”  This term was chosen to limit the scope of discussion to environmental conditions found in workplaces, differentiating them from military operations, athletics, and leisure activities.  The information provided remains valid in these contexts, but the objectives and decision-making, not to mention the clothing requirements, differ sufficiently to warrant explicit exclusion from the discussion of work environments.  Environmental considerations in these settings will be addressed, briefly, however, as a related topic.
     “Thermal,” as used here, has multiple connotations.  For one, it refers to the homeothermic nature of human beings.  The human body attempts to maintain a constant core temperature irrespective of its surroundings; homeo ≈ same, therm ≈ temperature.  With regard to surroundings, it is an umbrella term that encompasses several variables that influence a person’s perception of temperature and assessment of comfort.  These include the actual (air) temperature, humidity, air movement (e.g. wind), sunlight, and other sources of radiation.
     Comfort, as referenced above, is the subjective, individual perception of conditions.  Only thermal comfort will be considered here.  There are important distinctions between comfort, stress, and strain.  Stress and strain can be related to either high or low temperatures:

• stress – the net effect (i.e. heat load) of metabolic heat generation, clothing, and environmental conditions to which an individual is subject.
• strain – the physiological response to stress; i.e. changes in the body, made automatically, to retain (cold strain) or dissipate (heat strain) thermal energy.
  

Stress and strain are quantifiable phenomena, whereas comfort is a qualitative judgment of thermal stress or its absence.
     Even “heat” and “cold” warrant explicit mention, as their use blurs vernacular and technical meaning.  Technically speaking, heat is thermal energy; cold has no technical definition.  An attempt at rigid adherence to technical terminology in this discussion would be futile and counterproductive.  Conventional (i.e. vernacular) use of the terms suffice:

• heat – high or excess thermal energy; cooling desired.
• cold – low or insufficient thermal energy; warming desired.

A schematic representation of the continuum of thermal stress that spans these terms is provided in Exhibit 1.

     Coming full circle, we return to the title of this installment.  All of the terms discussed thus far are used in reference to biometeorology – the study of the effects of atmospheric conditions, such as temperature and humidity, be they naturally-occurring or artificially generated, on living organisms.  Our interest, of course, is in human biometeorology and how it influences job design.
     Job design defines a variety of elements of a person’s workplace experience. These may include the physical layout of a workstation or entire facility, equipment used, policies and procedures to be followed, and the schedule according to which tasks are performed.  All aspects of how and when work is performed are part of its job design.
     Understanding how the terms presented here are used is necessary to comprehend this series as a whole.  Other terms are introduced throughout the series in the context of relevant discussions.
 
Structure of the Series
     The “Thermal Work Environments” series is presented in several parts, in three loosely-defined “sections.”  The first section discusses hot environments, including the physiological effects on people working in elevated temperatures.  Measurements and calculations used to define and compare environmental conditions – specifically, the heat stress caused – are also presented.  Finally, recommendations are provided to assist those designing and performing tasks in minimizing the detrimental effects of heat stress.
     The second section discusses cold environments.  The presentation of information mirrors that of hot environments in the first section.  The final section is comprised of discussions of related topics that, while useful, could not be included seamlessly in the first two sections.
     The series structure described was derived with the following objectives:

• Limit the length and scope of each installment so that they are easy to consume and comprehend.
• Simplify future references to relevant material by making it easy to locate within the series’ installments.
• Promote a holistic approach to job design in environments subject to seasonal (or similar) variations by facilitating side-by-side comparison of considerations relevant to hot and cold environments.
• Simplify expansion or modification of the series to maintain its utility as knowledge and practices evolve.

     There is a series directory at the end of this post.  Links will be added as new installments are published; returning to this post provides quick and easy access to the entire series.
 
     For additional guidance or assistance with Operations challenges, feel free to leave a comment, contact JayWink Solutions, or schedule an appointment.
 
References
[Link] “A glossary for biometeorology.”  Simon N. Gosling, et al.  International Journal of Biometeorology; 2013.
 
Jody W. Phelps, MSc, PMP®, MBA
Principal Consultant
JayWink Solutions, LLC
jody@jaywink.com
 
Directory of “Thermal Work Environments” entries on “The Third Degree.”
Part 1:  An Introduction to Biometeorology and Job Design (17May2023)
Part 2:  Thermoregulation in Hot Environments (31May2023)
Part 3:  Heat Illness and Other Heat-Related Effects (14Jun2023)
Part 4: A Measure of Comfort in Hot Environments (28Jun2023)
Part 5:  Managing Conditions in Hot Environments (12Jul2023)
Part 6:  Thermoregulation in Cold Environments (18Oct2023)
Part 7:  Cold Injury and Other Cold-Related Effects (1Nov2023)
Part 8:  A Measure of Comfort in Cold Environments (15Nov2023)
Part 9:  Managing Conditions in Cold Environments (29Nov2023)