Empirical Study of PPE
Matthew C. Crouse MPA, CSP, CHMM
With Support from
Michael Schepige CIH CSP
Brian Forrester MD MPH
Jennifer W. Ray ASP
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farmers are feeding their chickens crushed ice to keep them from
laying hard-boiled eggs.
the cows are giving evaporated milk.
the trees are whistling for the dogs.
you learn that a seat belt makes a pretty good branding iron.
Any temperature below 90, you feel a bit chilly.
you've experienced condensation on your butt from the hot water
in the toilet bowl.
you discover that you can get a sunburn through your car
window.
you notice the best parking place is determined by shade instead
of distance.
your biggest bicycle wreck fear is, "What if I get knocked out and
end up lying on the pavement and cook to death?"
you realize that asphalt has a liquid state.
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Heat Stroke
Heat Exhaustion
Heat Cramps
Heat Syncope
Skin disorders
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the result of a combination of external factors
of heat on the worker
and
the ability of the worker to dissipate heat
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Environmental conditions
 temperature, humidity, heat index
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Work demands
Clothing requirements
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Potential for work environment to produce
heat stress depends on 3 independent factors:
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Amount of heat generated by the worker over time
Related to intensity and type of work performed
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External heat load
function of the ambient temperature plus the radiant
temperature
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Capacity for effective heat removal
humidity, air movement, personal health &
clothing
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Ambient temperature
Radiant temperature
Relative humidity
Air velocity
Physical activity level
Clothing cover and permeability
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Heat Strain: immediate physiological response
of the body to heat stress
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Increase in body temperature, heart rate, and
sweating
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Activity
 Bicycling
 Climbing Stairs
 Domestic Work
 Driving
 Heavy labor/factory work
 Light assembly/inspection
 Machine operator
 Office work
 Resting
 Standing (inactive)
 swimming
 walking on flat surface
Rate (kcal/hour)
360-600
360-720
75-300
120-180
210-400
90-160
120-240
75-120
60-90
90-120
300-880
300-400
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Primary defense against overheating is
sweating
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Each liter of sweat that evaporates removes 600 kcals
from the body
Healthy adult can sweat up to 1.5 liters of sweat per
hour
Ability of sweat to carry heat depends on its ability
to evaporate
Only small amounts of heat are lost by direct
convection to air or by radiation
Firefightinger'sHeat Stress Study.pdf
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Enhanced Recovery is critical when PPE must
be worn but it is important to remember that
air movement for cooling is only effective
below core temperature ~98.6
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Obesity
 Skin disease
 Decreased cutaneous blood flow
 Dehydration
 Hypotension
 Cardiac disease with decreased cardiac output
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Use of alcohol
Medications that inhibit sweating, reduce
cutaneous blood flow, or cause dehydration
Use of drugs that increase metabolic or muscle
activity
Advanced Age
Gender (women produce more internal heat than
men performing the same task)
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Infections
 Cancer
 Malnutrition
 Diabetes Mellitus
 Hyperthyroidism
 Cystic fibrosis
 Scleroderma
 Healed burns over a substantial body surface area
 Severe pervasive dermatitis
 Miliaria (heat rash)
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Senior Management decides it will improve the
safety of employees’ PPE. Amassing an
amazing team of experts, analysts, technical
professionals, and consultants.
Somebody is missing
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Garments on display after molten metal
testing at the Greensboro facility. Testing
revealed that both uniforms do protect
against molten metal splashing.
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All previous “problems” were easily identifiable
Given the myriad of factors that are influencing heat
illness, we are left with the clothing cover and
permeability factor.
 It had been observed that when the employees were
wearing Molten Metal Uniform their undergarments
were saturated with sweat while the outer garment
remained relatively dry for a much longer period of time
than that of the previous uniform.
 Simply put, if the sweat can’t get out then the body’s core
temperature will rise and increase the likelihood of heat
illness.
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Hypothesis -If heat can’t get in then heat can’t
get out thus increasing core body temperature.
Proposal -Measure the core body temperature
in an actual but controlled production
environment.
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 How is that Measured?
 Most Accurate is Rectally
 Alternate is Oral -Hypothalamic Equilibration of
sublingual and tympanic membrane
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A Questemp II dosimeter was used in to
measure internal and external temperature.
This was equilibrated with an oral
thermometer and cross referenced to a Wet
Bulb Globe Thermometer (WBGT).
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The same two healthy adult male employees were
utilized throughout the heat trials
All tests wore clean 100% cotton jockey stay cool t
shirts for undergarments
All tests wore new Molten Metal double layer
pants – Marlan fabric
Hard hats worn for all trials
Operation closely supervised and video recorded
to ensure consistent effort given during each of the
tests
All work performed in a limited and controlled
environment to be able to reproduce results
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Personal dosimeter has audible alarm that goes off
in their ear at 100.4 F to alert user they are
overheating – Never occurred during trial
Adequate rest rehydration periods between each
test. No more than 4 tests conducted on any given
day
All garments where the same except the shirts
being tested
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New Molten Metal Uniform - Marlan Fabric
Old Molten Metal Shirts – Alusafe Fabric
General Duty Uniform – Cotton Fabric
Electrical Shirt -FR Heavier Cotton Fabric
Old Uniform shirt -Vinex fabric
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Same Pants, same under shirts, PPE controlled
hydration, similar rest cycles, supervised work
to verify similar activity
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Word Summary of
Quest Data.docx
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Award from third party Insurance review:
 Tremendous degree of empirical validation by a
Master Black Belt
 Outstanding, compelling presentation that ought to
receive bonus points (community impact, goodwill) for
sharing beyond their own corporation,
 A fabulous story of living risk reduction over policy
enforcement, and
 A level of rigor and discipline in their data validation;
you can, unlike so many other “case studies”, take
these to the bank.
 Exceptional demonstration of the true value of
building a story on those closest to the risk
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There a multitude of factors that can affect the human
body’s ability to manage heat. Unfortunately, we have
little control over most of them whether they are from
the environment or from the individual. The one factor
we can control is our protective apparel and this
testing indicates that the Marlan in the uniform will
indeed raise the core body temperature at a rate faster
than that of other garments that provide similar
protection. Additionally, the retention of heat is
extended while wearing this garment. A few tenths of
a degree can be the difference between a minor heat
illness and a full blown medical emergency. This is
particularly evident when heat indexes are above the
body’s normal temperature.
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Understanding this information can help
prevent heat related illness or minimize their
severity and effect. Proper diet and hydration
is just as essential as rest breaks in cooler
environments. Encourage employees to
maintain their health, hydration, and taking
rest breaks in air conditioned environments
away from heat exposure will allow the body’s
primary cooling mechanism of sweating and
evaporation work to regulate homeostasis.
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How do you manage the heat?
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