Chapter 11 - Thermal Stressors

Question 1

Heat stress

Answer 1

Increase in body temperature, heart rate, and sweating

Question 2

Four sources of heat stress

Answer 2

Radiation, conduction, convection, and metabolic

Question 3

Heat transfer

Answer 3

heat always moves from warmer to cooler place

Question 4

Radiation heat

Answer 4

Amount of thermal radiation between two or more objects

Question 5

Convection

Answer 5

process whereby thermal energy is transferred by movement of a heated fluid such as liquid or air

Question 6

Conduction

Answer 6

transfer of thermal energy between two objects in contact with each other

Question 7

metabolic heat

Answer 7

generated from within the body through work - has potential to overheat the body

Question 8

Survival range for human body

Answer 8

97F-100F

Question 9

To regulate body temperature (to rid body of excess heat)

Answer 9

• varying rate and amount of blood circulation through the skin
  
  • heart pumps more blood, blood vessels expand, capillaries along upper layer of skin fill with blood- excess heat is lost to the cooler environment
• release of sweat from the glands
  
  • sweat is evaporated eliminating heat from the body (humidity affects evaporation making it more difficult to cool)

Question 10

Effects of heat stress

Answer 10

Increased blood at external surface of the body, less going to active muscles, brain and other organs
- strength declines, fatigue occurs, alertness and mental capacity also may be affected

Question 11

Accidents due to heat

Answer 11

due to sweaty and slippery palms, dizziness, fatigue, decreased alertness, fogging of safety eye ware, irritability, anger, emotion

Question 12

Heat exposure disorders

Answer 12

heat rash, heat cramps, heat syncope, dehydration, heat exhaustion, and heat stroke

Question 13

Heat cramps

Answer 13

excessive sweat and hydration without adequate replacement of body salts

Question 14

Heat syncope

Answer 14

Fainting as a result of exposure to heat- mild overheating with inadequate water or salt
blurred vision, fainting, normal body temperature
pooling of blood in the legs and skin from prolonged static posture an heat exposure

Question 15

Heat exhaustion

Answer 15

loss of large amounts of fluid and salts from excessive sweating
extreme fatigue, weakness, blurred vision, dizziness, high pulse rate, profuse sweating, low blood pressure, pale face, clammy skin, collapse, nausea and vomiting, headaches, and slightly increased body temperature- may lead to stroke

lie down flat on their back in a cool environment, drink water cool their skin and loosen clothing

Question 16

heat stroke

Answer 16

medical emergency- body temperature regulation system fails and sweating becomes inadequate or stops entirely- without treatment- death or brain damage

signs and symptoms- chills, restlessness, irritability, mental confusion, euphoria, red facce disorientation, hot dry skin, erratic behavior, unconsciousness, convulsions- temp greater than 104

Question 17

Heat Control - Engineering Methods

Answer 17

General ventilation - to dilute hot air with cooler air
Air treatment / cooling- removes heat and humidity from air
Air conditioning -
Use of chillers to circulate cool water through air heat exchangers over which air from the ventilation system is passed - can also reduce air humidity
Convection fans - can increase heat exchange
Insulating hot surfaces or tools
Heat shields - separate workers from heat generation

Question 18

Administrative/ Work Control Practices

Answer 18

Acclimation or acclimatization- gradual process - expose workers to approximately 20% on each day for five days - closely monitor new employees for heat-related injuries

Fluid replacement - equal to amount of sweat produced and with normal or near normal meals- caffeine not recommended

Work/ Rest cycles - Use WBGT Index

PPE- reflective clothing, auxiliary cooling- ice vests, water cooled garments, wetted terry cloth or cotton suits, wet scarf around the neck- sun block at least 15

Question 19

Heat stress training

Answer 19

knowledge of hazards
recognition of predisposing factors, danger signs, and symptoms
awareness of first aid procedures and potential effects
employee responsibilities
use of PPE
physical fitness to prevent heat-related disorders
fluid replacement
dangers of drug and alcohol in hot work environments
purpose and coverage of environmental and medical surveillance programs

Question 20

Heat stress prevention- additional measures

Answer 20

learning signs and symptoms
training workers about heat-related illness
perform the heaviest work during the coolest part of the day
acclimation of employees
use the buddy system
adequate fluid replacement (one cup water every 15-20min)
light loose-fitting breathable clothing
work/rest cycle
avoid caffeine and alcohol
PPE

Question 21

Cold stress

Answer 21

heat loss through radiation, conduction, convection, and evaporation

Question 22

Heat loss

Answer 22

Radiation- body heat loss to colder environments
Convection - body heat lost through direct contact with a cooler object
Convection- molecules against the surface of a warm body are moved away and replaced (wind chill example)
Evaporation- heat and fluid loss to the environment from sweating and respiration

Question 23

Safety problems related to cold

Answer 23

cold-related injuries- non- freezing and freezing
Non-freezing- chilblains, immersion injuries, hypothermia
Freezing- frostbite

Question 24

chillblains

Answer 24

pernio/perniosis- itchy tender red or purple bumps - a result of shutting down of blood vessels in cold conditions
contributing factors include familial tendency, peripheral vascular disease, low body weight or poor nutrition, hormonal changes, connective tissue disease, bone marrow disorders
little treatment- try to prevent secondary infection from scratching with steroidal cream
prevent chilblains with insulated workplaces, warm clothing, meds that constrict blood vessels, exercise before cold, cotton-lined waterproof gloves

Question 25

Immersion injuries- trench foot

Answer 25

prolonged exposure to cold weather

the injured foot is cold, swollen, waxy-white, with cyanotic burgundy to blue splotches, skis is anesthetic and deep musculoskeletal sensation is lost

air dry and elevate feet, clean dry socks, warm packs for 5 minutes, do not wear socks when sleeping or resting, medical attention

Question 26

hypothermia

Answer 26

reduction of body’s core temperature below normal - progressive deterioration in cerebral, musculoskeletal and cardiac functions
three stages- mild - violent shivering, virtual cessation of effective muscular activity, disorientation, and disinterest in surroundings 89-95
moderate - 78-89 - cardiac irregularities at 86, corneal reflexes absent below 82
severe- below 78 - may appear dead

Question 27

Frostbite

Answer 27

cellular injury and death from cellular trauma due tot he formation of ice crystals and from complex vascular reactions in cold exposure
first degree- similar to chillblain
second degree - blistering and desquamation
third degree - necrosis of skin and subcutaneous tissue with ulceration
fourth degree - destruction of connective tissue and bones and gangrene

Question 28

Frostbite prevention measures

Answer 28

observance and adherence to the wind chill factor
proper protective clothing - loose layered clothing, inner layer porous for airflow
proper nutrition and activity
fluid replacement or intake
training and discipline - physical conditioning, adequate personal hygiene, and signs and symptoms of cold-related injuries