Unit 3 - Section 1 - Commentary - Temperature

Question 0

Signs of heat exhaustion

Answer 0

Mildest form of heat stress:

• Faintness
• Nausea
• Vomiting
• Headache
• Restlessness

Replacement of lost water and sale, with rest, will cure heat exhaustion

Question 1

Define ambient environment

Answer 1

• Refers to features, properties, or characteristics of the immediate physical environment that surrounds us in any particular setting
• Include temperature, light, and sound

Question 2

Heat Stroke

Answer 2

Most serious form of heat stress

• Confusion
• Staggering
• Headache
• Delirium
• Coma
• Eventually, death

The sweating mechanism has broken down (the absence of sweat distinguishes it from heat exhaustion) and immediate cooling, such as immersion in ice water, is necessary for survival

Question 3

Hypothermia

Answer 3

• Lowering of the body core temperature
• As core body temperature approaches 32C, shivering is replace by muscular rigidity, confusion, and eventually, loss of consciousness.
• If warmth is not restored, coma and death from heart attack follow below a core temperature of about 25C

Question 4

List the factors that influence the impact of personal thermal stress

Answer 4

Factors that influence the impact of

Question 5

What is ambient air temperature?

Answer 5

The air temperature of the immediate surroundings

Question 6

What influences our perception of ambient temperature?

Answer 6

• Air temperature
• Humidity
• Air velocity
• In general, high humidity makes temperatures seem hotter than they actually are
• Air movement increases comfort through the cooling effect of evaporation

Question 7

Body reactions to cold temperatures

Answer 7

• Loss of manual dexterity and tactile sensitivity
• Increase in reaction time
• Takes longer to complete tasks

Question 8

What is acclimatization?

Answer 8

Increased physiological tolerance after continued exposure to high or low thermal environments.

Question 9

How does acclimatization influence a person’s response to temperature?

Answer 9

• Some thermal acclimatization may emerge from a genetically inherited ability to tolerate thermal extremes
• We can acclimatize to one or more environmental factors as with changing seasons, or exhibit diminished central nervous system reactivity to a particular stimulus
• Acclimatization takes a couple of days and is supplemented by behavioural adjustment such as changing clothes and changes in diet

Question 10

What happens with prolonged exposure to high ambient temperatures?

Answer 10

• Acclimatization achieved in 4 - 7 days
• Primary consequence of acclimatization to heat is increased sweating efficiency, the classic pattern is one of reduced discomfort, reduced heart rate, reduced body temperature, and higher volume of sweat with reduced concentration of salt
• Daily exposure of an hour or so is adequate to achieve acclimatization
• The better physical condition one is in, the faster the acclimatization is achieved

Question 11

Value of black skin

Answer 11

• Pigment provides some protection from sunburn and from overexposure to ultraviolet light
• Pigment increases skin temperature by increasing the absorption of heat, which promotes sweating
• Acclimatized Europeans showed the same response to heat as native Africans, including initial sweating at the same temperature, equivalent rates of sweating, and similar low salt content in the sweat

Question 12

What influence does high and low body temperature have on heat tolerance?

Answer 12

• Lower body temperatures = more tolerant of heat

- High body temperatures associated with low maximum oxygen intake

Question 13

What is a modal comfort envelope (MCE)?

Answer 13

A range of ambient conditions that will provide comfort for most people

Question 14

What are the physical and personal factors that influence personal thermal comfort?

Answer 14

1. Air temperature
2. Radiant temperature - heat sources in the environment - computers, stove, machinery, etc.
3. Air velocity - speed of the air moving over a person
4. Humidity - if water is heated and it evaporates to the surrounding environment, the resulting amount of water in the air will provide humidity
5. Clothing insulation - synthetic versus natural fabrics? Wicking fabrics?
6. Metabolic heat - the heat we produce inside our bodies as we carry out physical exercise

Question 15

What is the effect of heat on task performance?

Answer 15

• In some cases, task performance improves with heat, but ultimately, as the environment gets hotter and hotter, performance fails
• Depends upon the kind of task - the more complex the task, the worse the performance
• Performance gets even worse if other factors are added to high temperature such as loud noise or high altitudes

Question 16

Do low temperatures have an effect on task performance?

Answer 16

• Tasks that use the extremities are most noticeable
• Decreased tactile sensitivity, dexterity, and strength with exposure to low ambient temperature, particularly in windy or humid conditions
• Functioning remains near normal until a critical hand skin temperature (HST) is reached for the respective ability, then drops quickly

Question 17

Impact of temperature on behaviour

Answer 17

• Heat has a negative impact on attraction toward total strangers
• Due in part to the idea of “shared suffering”, heat does not damage previously established relationships
• High temperatures are associated with elevated crime rates
• People feel increased hostility when they are hot

Question 18

Influences of ambient temperature on social behaviours

Perception of ambient temperature and physiological mechanisms in thermoregulation

Answer 18

• Social and privacy pressures against removal of clothing or the use of highly transparent shelter prevent easy modes of coping with elevated ambient temperatures in many cultures
• Change in a number of physiological states, such as arousal, have marked effects on performance and other behaviours
• Since thermal stress has clear effects on physiology and comfort, it is not surprising that it influences