2007, Piran, Slovenia

Occupational Thermal Problems
PRODUCTIVITY LOSS FROM COLD
Daniel A. Goldman and Ralph F Goldman, PhD.
COMFORT TECHNOLOGY, Inc., Natick, MA., USA
Contact person: Ralphgoldman@CS.com
INTRODUCTION
Factors in cold weather productivity loss that should be considered include:
(1) The synovial fluid lubricating skeletal joints thickens, reducing finger agility.
(2) The skin dries, leading to a reduction in finger tactility.
(3) Skeletal muscles shorten if cooled, leading (inter alia) to a reduction in grip strength.
(4) Cold weather clothing reduces mobility (M ↑ 4%/layer) and constrains arm motion.
(4) ANY protective hand wear causes a greater loss of tactility and agility than cold per se. (5)
Protective headwear may interfere with hearing and vision; some interfere with speech.
(6) Clothing worn next to the skin (i.e., gloves, socks, underwear) tends to accumulate sweat
when performing heavier physical work and producing more heat than can be lost without
sweating.
(7) “Warmer” clothing does not produce extra heat, but only reduces the rate of heat loss from
the body.
(8) Only increasing active physical work increases body heat production; tasks that limit
mobility, e.g., connecting wires, soldering pipe connections, etc., only increase heat
production slightly.
(9) “BEHAVIORAL” temperature mechanisms against cold include adding clothing and
becoming increasingly active.
(10) The PHYSIOLOGICAL first line of defense against cold is vasoconstriction; i.e.,
reducing the blood flow from the body core (where the metabolic heat is produced) to the
shell (i.e., the skin, where core heat must be delivered by the blood flow so that it can be
eliminated from the body.
(11) The PHYSIOLOGICAL second line of defense is shivering. The maximum rate of
shivering heat production is ≈525 kcal/hr, and at this level the body is a non-functional
quivering block of tissue. Shivering decreases the air layer, and clothing, insulation and may
actually result in a net increase in body heat loss unless there is a high total Clo value.
The greatest source of productivity loss:
Based on experience as well as knowledge of the literature, the greatest losses of productivity
result from the absence of the worker from the work site. Certainly, the time spent by a
worker on a re-warming break, although essential to being able to continue to work after the
break, represents a totally non-productive interval. Experience also suggests that the worker
must be re-warmed before accumulating a heat debt of ~ 80 kcal of body heat store, or may
require such draconian re-warming that the worker will be unable to return to work that day.
One must view the work site, re-warming facilities, and the nature of the physical work and
its surroundings to accurately calculate the rate of body heat production and loss. This can be
used to determine the time before re-warming is essential, and the time that the workers will
require to get to the re-warming station, re-warm (usually 20 min), and get back to the job
site.
METHODS
Once one views the work site, re-warming facilities and their nature, and the nature of the
physical work and its surroundings, one can calculate the rate of body heat production, and
loss and, thus, the time before re-warming is essential, and also estimate the time required to
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