BLOCK 5: PHYSICAL/BIOLOGICAL HAZARDS AND CONTROLS - Unit 6: Thermal Stress (complete)

Question 1

The key to prevention of thermal injury is an _______________ of thermal risk factors by commanders, supervisors and individuals at all levels.

Answer 1

Awareness

Question 2

The thermal stress program is governed by ___________________________. (AFI)

Answer 2

AFI 48-151, Thermal Injury Prevention Program.

Question 3

What are BE’s responsibilities in the thermal stress program?

Answer 3

1.) BE performs initial surveillance, or screening, to detect or identify ambient threats or hazards that pose potential health risks.
2.) Base BE personnel are usually responsible for Wet Bulb Globe Temperature (WBGT) measurements and must specify in local instructions where estimations are to be taken.
3.) BE personnel are to determine the Fighter Index of Thermal Stress (FITS) zones based upon the WBGT measurement.
4.) BE personnel are responsible for conducting environmental monitoring for heat and cold injury risk assessment.

Question 4

The net heat load to which a worker may be exposed from the combined contributions of metabolic heat, environmental factors, (i.e. air temperature, humidity, air movement, and radiant heat), and clothing requirements.

Answer 4

HEAT STRESS

Question 5

The overall physiological response resulting from heat stress. The physiological responses are dedicated to dissipating excess heat from the body.

Answer 5

HEAT STRAIN

Question 6

Environmental and/or personal conditions that tend to remove body heat and decrease body temperature.

Answer 6

COLD STRESS

Question 7

The flow of energy and the associated physical and chemical changes constantly taking place in the billions of cells that make up the body; how the body produces heat.

Answer 7

METABOLISM

The rate of metabolism depends directly on the rate and type of external work demanded by the job. Metabolic heat is released from active skeletal muscles and transferred from the body core to the skin.

Question 8

Metabolic heat accounts for about _____ % of total energy expended.

Answer 8

70%

Question 9

Solid bodies of different temperatures have a net heat flow from the hotter surface to the cooler surface by ____________________.

Answer 9

ELECTROMAGNETIC RADIATION

Primarily Infared Radiation

Question 10

The rate of heat transfer by radiation depends on:

a.) average temperature of the surrounding solid surfaces
b.) skin temperature
c.) clothing
d.) all of the above

Answer 10

d.) ALL OF THE ABOVE (Avg. temp. of surrounding surfaces, skin temp., and clothing)

Question 11

Heat loss occurs when the surrounding objects have __________ surface temperatures than the body while heat gain occurs when heat from the sun or a radiator heats a person.

Answer 11

LOWER

Question 12

The transfer of heat in a moving fluid or air.

Answer 12

CONVECTION

The exchange of heat between the skin and the surrounding air is referred to as convection. The rate of convective heat exchange depends on the magnitude of the temperature difference, the amount of air motion, and clothing.

Question 13

When two solid bodies are in contact, heat will flow from the warmer body to the cooler body in a process called _______________.

Answer 13

CONDUCTION

Question 14

The removal of heat from an object by the vaporization of liquid.

Answer 14

EVAPORATION (Evaporative Heat Loss)

Question 15

Work-related heat stress can be impacted by the worker and the workplace. What are some of the worker impacts?

Answer 15

–> STRENGTH DECLINATION
–> EARLIER FATIGUE ONSET
–> AFFECTED ALERTNESS/MENTAL CAPACITY
–> LOWER COMPREHENSION OR RETENTION OF INFORMATION
–> INCREASED PRONENESS TO ACCIDENT DUE TO SWEATING, DIZZINESS, ETC.
–> SOME PHYSIOLOGICAL REACTIONS MAY CAUSE WORKERS TO SUBVERT SOME SAFETY PROCEDURES OR IGNORE OUTRIGHT CERTAIN HAZARDOUS TASKS

Question 16

Heat-related disorders may result due to over-exposures to heat stress. What are some of the risk factors contributing to heat-related disorders? (There are 7 listed in the study guide)

Answer 16

• Dehydration
• Individual protective equipment
• Salt depletion
• Lack of acclimatization
• Failure to observe work-rest cycles
• Poor physical condition
• Drugs which inhibit sweating

Question 17

In accordance with AFI 48-151, _______________ is an all-embracing term and applies to an individual who becomes incapacitated as the result of a rise in core body temperature.

Answer 17

HEAT ILLNESS

In general, any individual experiencing the following signs or symptoms during physical activity in a hot environment or while wearing protective clothing should be presumed to be suffering from heat illness:

• Dizziness or confusion
• Nausea or vomiting
• Staggering
• Disturbed vision
• Confusion, collapse, or loss of consciousness

Question 18

The most serious heat-related disorder. It occurs when the body’s temperature regulation fails, and the body is unable to get rid of excess heat. Body temperature rises to critical levels.

Answer 18

HEAT STROKE

Heat stroke is a medical emergency!

Question 19

A milder form of heat-related illness. It is caused by excessive exposure to heat and the depletion of body fluids.

Answer 19

HEAT EXHAUSTION

Question 20

The result of exposure to high temperatures. It may be associated with exercising in heat, with the pooling of blood in the legs and skin from prolonged static posture (i.e. standing or sitting too long), and with heat exposure.

Answer 20

HEAT SYNCOPE (FAINTING)

Question 21

Muscle pains or spasms that may occur during or following strenuous physical activity. Muscles, often those in the legs, abdomen, and arms, cramp and produce severe pain; attributed to electrolyte imbalance caused by sweating without adequate fluid or salt intake.

Answer 21

HEAT CRAMPS

Question 22

Caused by prolonged, uninterrupted sweating and inadequate hygiene practices.

Answer 22

HEAT RASH

Also known as prickly heat, is a common problem in hot work environments. Small bumps appear, especially in areas where the clothing is restrictive, and there is an itching or a prickling sensation.

Question 23

The first physiological response to cold stress is to conserve body heat by _______________ blood circulation through the skin.

Answer 23

REDUCING

This effectively makes the skin an insulating layer. Because heat is lost from the exposed body surface faster than it is replaced, skin temperature drops. The reduced blood flow and fall in skin temperature contribute to the cause of peripheral cold injuries, particularly to the fingers, toes, ears, and nose.

Question 24

A serious health condition that develops as the rate of heat loss exceeds heat
production. It is defined as a core temperature below 35°C (95°F).

Answer 24

HYPOTHERMIA

As skin temperature approaches 30°F, there is a potential for freezing of tissues and subsequent frostbite, categorized as freezing cold injuries (FCIs).

Question 25

Occurs when the skin/tissue freezes. It usually occurs at temperatures of 30°F or lower; however, it may occur at above freezing temperatures depending on wind-chill factors.

Answer 25

FROSTBITE

Frostbite commonly occurs in the extremities, particularly the feet and hands and tips of the
nose and ears.

Question 26

A milder cold injury that does not cause tissue loss. It is the reversible freezing of superficial skin layers and is usually marked by numbness and whiteness of the skin with possible itching or pain. Non-freezing cold injury (NCFI) is characterized by tissue damage following prolonged exposure to temperatures above freezing.

Answer 26

FROSTNIP

Question 27

A cold injury sustained by tissues exposed to cold, wet conditions for prolonged periods of time. It can occur in any tissue but is most common in the foot. These injuries may occur because of actual immersion or by the creation of cold and wet conditions such as prolonged walking on boggy ground or sweating in impervious boots.

Answer 27

TRENCH FOOT

Question 28

A painful, itching swelling of the skin typically on the hand or foot caused by poor circulation when exposed to cold; typically occurs after one to five hours in cold, wet conditions at temperatures below 50ºF (16ºC).

Answer 28

CHILBLAIN

Question 29

Not considered an FCI or NFCI. It is an autoimmune disorder in which spasms in the blood vessels can interrupt blood flow to the fingers, toes, nose and ears. It is mentioned here because exposure to cold can trigger the spasms, typically causing the affected area to turn white, then blue, then bright red. In severe cases this may lead to digital ulcers and tissue loss.

Answer 29

RAYNAUD’S DISORDER

Question 30

Heat stress assessment combines four thermal components:

Answer 30

• Air temperature
• Humidity
• Air speed
• Radiant heat

Question 31

An instrument for providing information on hot weather risks consisting of three thermometers.

Answer 31

WBGT KITS

Question 32

Acclimatized individual(s) are those that have spent 10-14 days exposed to the __________ environmental conditions.

Answer 32

SAME

Question 33

____________________ are responsible for determining Frostbite Risk Levels (FRL) Severity.

Answer 33

BE Personnel

Question 34

ENGINEERING CONTROLS FOR HEAT STRESS MANAGEMENT:

Brings in a supply of cooler air from another area and reduces the temperature in the work area by diluting the hot air with cooler air. This can be accomplished with general area ventilation or local (spot) ventilation such as fans.

Answer 34

DILUTION VENTILATION

Question 35

ENGINEERING CONTROLS FOR HEAT STRESS MANAGEMENT:

Mechanical refrigeration, evaporative cooling, active cooling fan or a water chiller is used to reduce the temperature of supplied air for dilution ventilation.

Answer 35

ACTIVE COOLING

Question 36

ENGINEEING CONTROLS FOR HEAT STRESS MANAGEMENT:

Can be used to control radiant heat from a specific source (i.e boiler plant or furnace) and can be localized. For example, an insulated or reflective barrier between the source and the receiver can interrupt the pathway. Smooth polished surfaces such as stainless steel reflect heat back towards the source, and flat black surfaces absorb heat.

Answer 36

SHIELDING

Question 37

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Characterized by a series of physiological adjustments that occur when an individual is exposed to a hot climate. In other words, the body adapts to the hot environment over a period of time.

Answer 37

ACCLIMATIZATION

Acclimatization is usually achieved through a schedule of increasing exposures and occurs during the first 10 to 14 days of heat exposure. An individual is considered acclimatized if he or she has undertaken regular exercise for longer than 10 days in the same environmental conditions as the proposed activity.

Question 38

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Methods to reduce the metabolic rate can go a long way toward reducing heat stress. The rate is reduced when the same amount of work is performed over a longer period of time. Any idle time inherent in the work process should be spent in cooler areas to realize the full benefit.

Answer 38

WORK PACE

Question 39

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Another way to reduce metabolism is to distribute the work among other workers. This may require some work be postponed to another time.

Answer 39

WORK SHARING

Question 40

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Supervisors may schedule work to reduce the contribution of environmental heat to heat stress. This includes scheduling nonessential work to cooler times of the day.

Answer 40

WORK SCHEDULING

Question 41

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Predetermined work times are assigned to a worker or crew before a job begins. They are allowed to extend the work time with the knowledge that heat stress will eventually affect their ability to work and that they should stop working at the first sign of heat strain. Workers/supervisors may also lower peak work demands and make the work demands lighter.

Answer 41

WORK TIMES, SELF DETERMINATION, AND PERSONAL MONITORING

Question 42

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

In hot environments, a great deal of water is lost from the body in the form of sweat. This water must be replaced to prevent adverse effects from heat. Drinking water is a must in order to prevent heat injury.

Answer 42

FLUID REPLACEMENT

Question 43

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

Adequate sleep, a good diet, exercise, and a healthy lifestyle, including no abuse of alcohol or drugs, are important to lowering the risk of a heat-related disorder.

Answer 43

DIET, LIFESTYLE, AND GENERAL HEALTH

Question 44

ADMINISTRATIVE CONTROLS FOR HEAT STRESS MANAGEMENT:

• Description of heat stress: Environment, work demands, and clothing
• Physiological responses including acclimatization
• Recognition of first aid measures for heat-related disorders
• Heat stress hygiene practices such as individual’s actions to reduce the risks to a heat disorder (fluid replacement, diet, terminating heat exposure at the first symptom of a heat-related disorder). Emphasis should be placed on individual responsibility.
• Overview of heat stress policy and guidelines
   Workplace/Unit/Base policy
   Management responsibilities
   Employee responsibilities
• Nuclear, biological, and chemical (NBC) operations and heat stress in both hot and cold
  environments

Answer 44

AWARENESS TRAINING

Question 45

PPE CONTROLS FOR HEAT STRESS MANAGEMENT:

Circulating air as a personal cooling method consists of circulating air under the clothing and around the torso. It requires the delivery of air to the individual either through a high-pressure airline and a pressure reducer or by a portable (self-contained) blower. Circulating air under the clothing effectively increases the amount of convective and evaporative cooling of the body.

Answer 45

CIRCULATING AIR SYSTEM

Question 46

PPE CONTROLS FOR HEAT STRESS MANAGEMENT:

A second type of personal cooling is a system that circulates cool water through tubes and channels around the body. The system could virtually cover the whole body or only portions of the back and chest.

Answer 46

CIRCULATING WATER SYSTEM

Question 47

PPE CONTROLS FOR HEAT STRESS MANAGEMENT:

Ice vests (Figure 45) can be used to control heat strain by removing body heat from the skin to the packets of ice. The vests provide good mobility, with some bulk around the torso. The ability to cool
and the length of time an ice vest is effective depends on the rate of work, the amount of ice, and the design of the particular garment.

Answer 47

ICE GARMENTS

Question 48

PPE CONTROLS FOR HEAT STRESS MANAGEMENT:

Designed to reduce the amount of heat reaching the individual and is best suited for sources of high radiant heat. There is a tradeoff in that it reduces sweat evaporation and could actually increase the level of heat stress of the worker.

Answer 48

REFLECTIVE CLOTHING

Question 49

What are some examples of cold stress engineering controls?

Answer 49

Engineering controls for cold stress reduce heat loss from the person as a whole or from
exposed skin. They include:
* General or spot heating including hand warming (a small heater blowing warm air on the
hands)
* Minimizing air movement (shielding, adjusting ventilation)
* Reducing conductive heat transfer (no metal chairs or uninsulated tools)
* Redesigning equipment, processes, etc., to control systemic and local cold stress
* Providing temporary shelter (preferably heated) for essential outdoor work

Question 50

Which of these is not an administrative control for cold stress?

a.) scheduling to work in warmer/warmest times
b.) moving to warmer areas
c.) wearing gloves or mittens
d.) proper eating and drinking habits

Answer 50

c.) WEARING GLOVES AND MITTENS

This is a ppe related control for cold stress.

Question 51

List the 5 mechanisms of Thermal Exchange

Answer 51

–> METABOLISM
–> RADIATION
–> CONVECTION
–> CONDUCTION
–> EVAPORTATION

Question 52

If air temperature is greater than skin temperature, convection is ________________ and heat flows from the air to the skin. If the air is cooler than the skin, convection is ________________ and heat flows from the body to the air.

Answer 52

POSITIVE ; NEGATIVE

Question 53

________________ is the first physiological response to cold stress.

Answer 53

REDUCTION OF BLOOD CIRCULATION (to conserve body heat)

Shivering also factors into this. The first physiological responses are defined to be cutaneous vasoconstriction and shivering thermogenesis. The former conserves body heat and the latter increases metabolic heat production.

Question 54

What is the term for when an individual is incapacitated as a result of increased body temperature?

Answer 54

HEAT ILLNESS

Question 55

How is the current heat condition passed along to the base population?

a.) WBGT
b.) alarm sirens
c.) flag color
d.) letters

Answer 55

FLAG COLOR

Question 56

How is heat produced by the body?

a.) radiation
b.) metabolism
c.) conduction
d.) convection

Answer 56

METABOLISM

Question 57

What is defined as environmental or personal conditions that tend to remove heat and decrease body temperatures?

Answer 57

COLD STRESS

Question 58

TRUE OR FALSE:

Heat Stroke is the most serious heat stress related disorder.

Answer 58

TRUE

Question 59

The length of the typical acclimatization period is __________

Answer 59

10-14 days

Question 60

What two variables are needed to determine Frostbite Risk Level (FRL) Severity?

Answer 60

WIND SPEED AND TEMPERATURE