Definition of Pressure
Boyles Law & Dalton's law of partial pressures
Sources of pressure hazards in the body
Boilers and Pressure Hazards
High-temperature water (HTW) hazards
Define and know hazards of Unfired Pressure Vessels
Diagram of a typical pressure vessel showing potential points for leakage or rupture.
2. Introduction
• A work environment in which the temperature is not
properly controlled can be uncomfortable.
• Extremes of either heat or cold can be more than
uncomfortable—they can be dangerous.
• Heat stress, cold stress, and burns are major concerns
of modern safety & health professionals.
3.
4. Introduction
• Temperature, humidity, air distribution, personal
preference, and acclimatization are all determinants of
comfort in the workplace.
• Determining optimum conditions is not a simple process.
Acclimatization: It is the increase in body's physiological adaptation and
tolerance to the environmental temperature which occurs over time (ACGIH®).
5. Thermal Comfort
• Conduction is the transfer of heat between two bodies
that are touching, or from one location to another
within a body.
• Convection is transfer of heat from one location to
another by way of a moving medium (gas or liquid).
6. Thermal Comfort
• Metabolic heat is produced within a body as a result
of activity that burns energy.
• Environmental heat is produced by external sources.
• Radiant heat is the result of electromagnetic
nonionizing energy transmitted through space, without
the movement of matter within that space.
9. Heat Stress
• Heat stress: The net burden of heat experienced by the body
when it is exposed to extremely hot environments and causes a rise in
body core temperature. The heat burden can cause various health
effects and discomfort levels (ACGIH®).
• may be exposed from the combined contributions of:
• Metabolic effect of work; clothing requirements
• Environmental factors,
• Air temperature, humidity, movement, and radiant heat.
• Mild or moderate heat stress may cause discomfort and
may adversely affect performance and safety.
10. Heat Illnesses or Disorders
• Before severe heat stress begins, the body tries to remove the excess
heat.
• Known as heat strain, this is the deployment of bodily processes such
as sweating, blood flow to skin, breathing rate and metabolic rate
• However, after some time of exposure these processes may not be
long enough to control body temperature and the body begins to
overheat and the heat related disorders begin.
11. Heat Edema
• Swelling in extremities in first 7 to 10 days
• Most noticeable in the ankles
• people who are not acclimatized to working in hot conditions.
Swelling is often most noticeable in the ankles.
• Resolves spontaneously
• Need at least 2 weeks to gradually increase time in hot environments
to be come acclimatized.
15. Heat Exhaustion
• Heat exhaustion is the body’s response to an excessive loss of water
and salt, usually through excessive sweating. Heat exhaustion is most
likely to affect:
• The elderly
• People with high blood pressure
• Those working in a hot environment
16. Heat Stroke
• Most serious heat-related illness; life-threatening
• occurs when the body can no longer control its temperature
• Body temperatures rise rapidly
• Sweating mechanism fails
• The body is unable to cool down
• Symptoms: Throbbing headache, confusion, nausea, dizziness, body
temperature above 104°F (40° C), hot, red, dry or damp skin, rapid
and strong pulse, fainting, loss of consciousness.
17. Heat Stroke
• Move the worker to a shaded, cool area and remove outer clothing.
• Cool the worker quickly, using the following methods:
• With a cold water or ice bath, if possible
• Wet the skin
• Place cold wet cloths on the skin
• Soak clothing with cool water
• Circulate the air around the worker to speed cooling.
• Place cold wet cloths or ice on the head, neck, armpits, and groin; or soak
the clothing with cool water.
• Do not give cool drinks/fluids
18. Heat Rash
• A skin irritation(prickly rash) caused by excessive sweating
during hot, humid weather. Sweat does not evaporate.
Treatment
• Work in a cooler, less humid environment, if possible.
• Keep the rash area dry.
• Apply powder to increase comfort.
• Don’t use ointments and creams.
• Periodic rest breaks in a cool environment that allows sweat
to evaporate will prevent heat rash.
19. Recognizing Heat Strain
• Signs of excessive heat strain:
• A sustained rapid heart rate.
• 180 beats per minute, minus the employee's age in years.
• Core body temperature is greater than 38.5 deg C.
• Sudden & severe fatigue, nausea, dizziness, or light-
headedness.
20.
21. Heat Stress
• Widely used heat stress-related terms:
• Work tolerance time (WTT) - A formula to determine what
steps can be taken to allow a worker to safely perform
required tasks, in the environment in question, for the time
required.
• Considers factors such as temperature, humidity, level
of energy expended in performing the task, rest periods,
and personal protective equipment (PPE).
22. Heat Stress
• Widely used heat stress-related terms:
• Moisture vapor transfer rate (MVTR) - A measure of the
ability of the fabric used in making PPE to dissipate heat.
• Even the lightest cotton fabric is less capable of dissipating heat when
the unclothed body is used for baseline comparisons.
26. Heat Stress Management - General
Controls
• ACGIH recommends the following general controls:
• Provide accurate verbal and written instructions, training
programs, & information about heat stress and strain.
• Encourage drinking small volumes of cool water about every
20 minutes.
• Permit self-limitation of exposure and encourage coworker
observation to detect signs & symptoms of heat strain.
27. Heat Stress Management - Specific
Controls
• ACGIH recommends the following specific controls:
• Establish engineering controls that reduce metabolic rate.
• Provide general air movement; Shield radiant heat sources.
• Reduce process heat and water-vapor release.
• Consider administrative controls that set acceptable
exposure times, allow sufficient recovery & limit physiological
strain.
• Consider personal protection demonstrated effective for the
specific work practices and conditions at the location.
28. Regulating Heat Stress
• WBGT Index
• Use ACGIH TLV booklet
• Regulates the work rest regimen depending on heat measured
• Humidity
• Air velocity
• Air Temperature
• Radiant Heat
29. WBGT
• Wet Bulb, Globe, Temperature
• Wet Bulb
• estimates the effect of temperature, relative humidity, wind speed, and solar
radiation on humans using a combination of temperatures from three
thermometers: A Wet bulb measures the temperature read by a
thermometer covered in a wet cloth. As water evaporates from the cloth,
evaporation cools the thermometer.
30. WBGT
• Globe
• Measures the effect of radiant heat on temperature (solar radiation)
• Uses a black globe with matte paint with sensor on the inside
• Temperature (Dry Bulb)
• Measures ambient air temperature
• Useful in determination of comfort zone for lightly clothed sedentary workers
• Temperature on thermometer outside
31. Calculation
For indoor or outdoor conditions with no direct sunlight, WBGT is
calculated by using the following formula:
WBGT = 0.3 x globe temperature + 0.7 x wet bulb
temperature
For outside
WBGT = 0.2 gt + 0.7 wb +0.1 db
32.
33.
34.
35. ACGIH Assumptions
• Fit, acclimatized workers
• Summer uniform
• Plenty of Fluids
• Rest Area at Same Temperature
• No hard hats, respirators
36.
37.
38. Clothing Corrections
• Must add degrees to temperatures if these clothing are worn
• Anything other than a summer uniform means less time spent in a
heated environment
43. Cold Stress
• A condition that occurs when the body can no longer maintain (or
regulate)its normal temperature.
• First your skin temperature drops then your core body temperature
• The results can include serious injuries resulting in permanent tissue
damage or death
44.
45. How Workers are Exposed
Five main factors cause cold stress. Workers can be affected by:
• Naturally or artificially cooled environments
• Wind, which pulls heat away from the body in any environment
• Wet clothing, from sweat or water
• Cold water immersion, which cools the body 25 times faster than cold
air
• Fatigue, which makes it harder for the body to create heat
46.
47.
48.
49.
50. Hypothermia
• When exposed to cold temperatures, your body begins to lose heat faster
than it is produced.
• Prolonged exposure to cold will eventually use up your body’s stored
energy. The result is hypothermia or abnormally low body temperature.
• A body temperature that is too low affects the brain, making the victim
unable to think clearly or move well. This makes hypothermia particularly
dangerous because a person may not know it is happening and will not be
able to do anything about it.
• Excessive exposure to cold stress can result in impaired judgment,
reduced alertness, and poor decision making.
• Acute cold stress can cause reduced muscular function, decreased
tactile sensitivity, reduced blood flow, and thickening of the synovial
fluid.
51. Cold Stress
Chronic cold stress can lead to reduced functioning of the
peripheral nervous system.
• When work is to be performed in an environment with
an air temperature of 4 deg C or less, total body
protective clothing is advisable.
52.
53. FIGURE 17–3 The body's response to reducing its core temperature.
54. Trench Foot
• also known as immersion foot, is an injury of the feet resulting from
prolonged exposure to wet and cold conditions.
• Trench foot can occur at temperatures as high as 60 degrees F if the
feet are constantly wet. Usually occurs within 3 to 12 hours of
exposure
• Injury occurs because wet feet lose heat 25-times faster than dry feet.
To prevent heat loss, the body constricts blood vessels to shut down
circulation in the feet. Skin tissue begins to die because of lack of
oxygen and nutrients and due to the buildup of toxic products.
(occurs after 12 hours to 3 days)
55.
56. Frost Nip
• Mild irritation of skin
• Reversible
• Superficial freezing
• No loss of tissue
• Your skin may get pale or turn red and feel extremely cold or numb.
• The affected area may sting, prickle, or burn, and have a deep cold
feeling. This will progress into a tingling or a numbness.
• Many people describe an intense burning sensation as the skin begins
to warm up and thaw out.
57.
58.
59.
60.
61. Preventing Cold Stress
• Whether employees are exposed to cold air or are
immersed in cold water, wind can magnify the level of
cold stress.
• The phenomenon often referred to as windchill.
64. Nova Scotia Regulations
• ACGIH TLV Booklet for Cold Stress
• https://novascotia.ca/lae/healthandsafety/docs/Cold-Stress-
Guidelines.pdf
65.
66.
67.
68. Preventing Cold Stress
• At equivalent air temperatures of 2 deg C employees
who are immersed in water or whose clothing gets wet
should be treated for hypothermia immediately.
70. Preventing Cold Stress
• Strategies that can decrease hazards of cold stress:
• When working in a cold setting in which clothing may get wet,
apply one or more of the following strategies:
• For light work, wear an outer layer of impermeable clothing.
71. PPE for Cold Environments
• When working in a cold environment, provide the right
PPE for the conditions that exist.
• PPE for cold environments might include face
protection, head protection, ear protection, wind vests,
wind-blocking jackets, over suits, warming vests, hand
warmers, foot warmers, gloves, wind-and-water
insulated clothing, cold-insulated footwear, ice cleats,
slip resistance footwear, and glare protection.
72. PPE for Cold Environments
• In selecting PPE for cold environments, it is advisable to
ask employees to participate. This can provide two
benefits:
1. Employees are more likely to wear PPE they picked out
(employees are less likely to wear PPE they do not like)
2. The PPE is more likely to fit properly if employees
participate in its selection (poor fit is a main reason
employees do not wear PPE when they should).
76. Industrial chemicals or cleaning products are common causes of chemical burns to one
or both eyes. Thermal burns to the eye also occur, often among welders. These burns
routinely damage workers’ eyes and surrounding tissue.
Chemical & Thermal Burns - Eyes
77. Burns and Their Effects
• Human skin is the tough, continuous outer covering of
the body, consisting of two main layers:
• The outer layer, which is known as the epidermis.
• The inner layer, known as the dermis, cutis, or corium.
• The dermis is connected to the underlying subcutaneous tissue.
78. Burns and Their Effects
• Burns disrupt the normal functioning of the skin, the
deeper the penetration, the more severe the burn.
• Burn severity of a burn depends on the depth the burn
penetrates, location of the burn, age of the victim, and
amount of burned area.
79. Human Skin
• Protection from fluid loss, water penetration,
ultraviolet radiation, and infestation by
microorganisms is a major function of the skin.
• Sensory functions of touching, sensing cold,
feeling pain & sensing heat involve the skin.
• Skin helps regulate body heat through the
sweating process.
• Excreted sweat removes electrolytes and certain
toxins.
80. Human Skin
• By giving off minute amounts of carbon dioxide
& absorbing small amounts of oxygen, the skin
aids slightly in respiration
• Burns can disrupt any or all of these functions,
depending on their severity.
82. Severity of Burns
• Second-degree burns are easily recognizable from the
blisters that form on the skin.
• If superficial, the skin will heal with little or no scarring.
• A deeper burn will form a thin layer of coagulated, dead cells that feels
leathery to the touch.
83. Severity of Burns
• Third-degree burns are very dangerous and can be fatal.
• Penetrates through both the epidermis and the dermis.
• A deep third-degree burn will penetrate body tissue.
84. Severity of Burns
• Third-degree burns can be caused by both moist and
dry hazards.
• Moist hazards—such as steam & hot liquids—cause burns that
appear white.
• Dry hazards—such as fire & hot objects/surfaces—cause burns
that appear black and charred.
85. Severity of Burns
• Amount of surface area covered is a critical concern.
• Expressed as a percentage of body surface area (BSA).
• Burns covering over 75% of BSA are usually fatal.
• Using burn-degree classifications in conjunction with BSA
percentages, burns can be classified further as minor,
moderate, or critical.
87. Minor Burns
• All first-degree burns are considered minor.
• Second-degree burns covering less than 15% of the
body are considered minor.
• Third-degree burns can be considered minor provided
they cover only 2% or less of BSA.
88. Moderate Burns
• Second-degree burns that penetrate the epidermis and
cover 15% or more of BSA are considered moderate.
• Those that penetrate the dermis & cover from 15 to 30% of
BSA are considered moderate.
89. Moderate Burns
• Third-degree burns can be considered moderate
provided they cover less than 10% of BSA.
• And are not on the hands, face, or feet.
90. Critical Burns
• Second-degree burns covering more than 30% percent
of BSA or third-degree burns covering over 10% of BSA
are considered critical.
91. Chemical Burns
• Hazards of chemical burns are very similar to those of
thermal burns.
• They destroy body tissue, and extent of destruction depends
on the severity of the burn.
• Chemical burns continue to destroy body tissue
until the chemicals are washed away completely.
92. Chemical Burns
• Many concentrated chemical solutions have an affinity
for water, and when in contact with body tissue, they
withdraw water so rapidly the original chemical
composition of the tissue is destroyed.
• The more concentrated the solution, the more rapid the
destruction.
93. Chemical Burns
• Severity of the burn depends on these factors:
• Corrosive capability of the chemical.
• Concentration of the chemical.
• Temperature of the chemical or the solution in which it is
dissolved.
• Duration of contact with the chemical.
95. Effects of Chemical Burns -
Infection/Fluid Loss
• The risk of infection is high with chemical burns, as the
body's primary defense against infection-causing
microorganisms (the skin) is penetrated.
• Infection in a burn wound can cause septicemia (blood
poisoning).
96. Effects of Chemical Burns -
Infection/Fluid Loss
• Body fluid loss in second- and third-degree burns can
be serious.
• With second-degree burns, blisters on the skin often fill with
fluid seeping out of damaged tissue under the blister.
97. Effects of Chemical Burns -
Infection/Fluid Loss
• Body fluid loss in second- and third-degree burns can
be serious.
• With third-degree burns, fluids are lost internally, and can
cause the same complications as a hemorrhage.
• If these fluids are not replaced properly, the burns can be fatal.
98. Shock
• Shock is a depression of the nervous system, and can
be caused by physical or psychological trauma.
• In cases of serious burns, it may be caused by the intense
pain that can occur when skin is burned away.
99. Shock
• Shock from burns can come in two forms:
• Primary shock, which is the first stage and results from
physical pain or psychological trauma.
• Secondary shock, which comes later, caused by a loss of fluids
and plasma proteins as a result of the burns.
100. First Aid for Chemical Burns
• The proper response to chemical burns is to wash off
the chemical by flooding the burned areas with copious
amounts of water as quickly as possible.
101. First Aid for Chemical Burns
• In the case of chemical burns to eyes, continuous
flooding should continue for at least 15 minutes.
• Eyelids should be held open to ensure that chemicals are not
trapped under them.
102. First Aid for Chemical Burns
• If chemicals have saturated the employee's clothes,
they must be removed quickly, while flooding the body
or the affected area.
• If necessary clothing should be ripped or cut off.
103. First Aid for Chemical Burns
• Health and safety professionals should ensure that
special eye wash and shower facilities are available
wherever employees handle chemicals.
