Heat Stress Program

Navy Region Singapore 2007

A. Physiology of Heat Stress

Physiology of Heat Stress

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The effect of factors on the body as it tries to regulate body temperature

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The body generates heat; is sensitive to external heat factors

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The body tries to regulate internal temperatures naturally

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Failure of natural cooling ability causes heat stress

Types of Heat Affecting the Body

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Air temperature Thermal radiation Humidity Air flow (ventilation)

Symptoms of Heat Stress

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Fatigue Severe headaches Nausea Decreased performance

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Physical

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Mental

Causes of Heat Stress

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High humidity + Heavy exercise + Heat Radiation + Low convective heat loss High humidity decreases heat loss through evaporation of sweat Heavy exercise increases metabolic heat production Heat radiation from the sun or hot objects (asphalt, etc.) Heat layer next to skin can be caused by lack of air currents over skin (low convective heat loss) Poor physical condition

Heat Stress Prevention

• • • •

STAY HYDRATED!!

Avoid caffeine Avoid salt tablets

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Salt is generally well-replenished in food Allow time for acclimatization

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Increased tolerance to heat and more efficient cooling by body (more sweat, less salt loss, etc.)

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Can be achieved in as little as 3 weeks

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Two 50 minute periods of work per day (in heat)

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Does not necessarily indicate that no health effects will be experienced under higher heat conditions

B. Navy Heat Stress Control Program

Responsibilities

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CNO

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Set Policy in OPNAVINST 5100.23 (shore commands) NEPMU6

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Assist and consult with heat stress program implementation, follow through, and improvement

Responsibilities

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Commanding Officer (or designee)

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Establishes and enforces Heat Stress Program

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Ensures Heat Stress Deficiencies corrected

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Requests assistance to identify problems

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Reports injuries & conducts investigations

C. Heat Stress Program Parameters

Heat Stress Program Parameters

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Monitor heat stress potential

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Take outdoor WBGT readings daily

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Should be taken at:

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0900, 1100, 1300, and 1500 on any day when the dry bulb > 80 degrees F.

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Log readings!

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Exhibit proper colored flag as needed

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Consult NEPMU6 Industrial Hygiene for guidance

Flag Codes

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White Flag

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WBGT is <80 degrees F Green Flag

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WBGT between 80 and 84.9 degrees F Yellow Flag

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WBGT between 85 and 87.9 degrees F Red Flag

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WBGT between 88 and 89.9 degrees F Black Flag

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WBGT > 90 degrees F

Flag Meanings

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White Flag

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Heat Condition V- Extremely intense physical exertion may precipitate heat exhaustion or heat stroke in un-acclimatized personnel. Therefore, caution should be taken.

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Green Flag

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Heat Condition IV- Discretion is required in planning heavy exercise for acclimatized personnel.

Flag Meanings Continued

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Yellow Flag

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Heat Condition III- Strenuous exercise and activity (i.e. close order drill) should be curtailed for new and un-acclimatized personnel during the first three weeks of heat exposure.

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Red Flag

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Heat Condition II- Strenuous exercise should be curtailed for all personnel with less than 12 weeks training in hot weather.

Flag Meanings Continued

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Black Flag

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Heat Condition I- Physical training and exercise should be suspended for all personnel (excludes operational commitment not for training purposes).

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Heat stroke likelihood high under conditions of high exertion.

Signs and Symptoms

Heat Exhaustion

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Symptoms

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Profuse sweating

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Pale and clammy skin

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Pulse fast and weak

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Breathing fast and shallow

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Dizziness

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Nausea

Heat Cramps

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Caused primarily through excessive salt loss through sweating

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Painful and severe cramping of voluntary muscles

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Need to stop exercising, replenish fluids/electrolytes, and stretch

Heat Syncope

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Caused by pooling of blood in extremities

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Caused by dilation of blood vessels to cool body by heat transfer to air

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Can cause loss of consciousness

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Cool victim quickly and begin fluid/electrolyte replacement

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Transport to medical treatment facility

• – – – – – –

Heat Exhaustion Caused by peripheral vascular collapse

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Symptoms include

• • • • • • •

Profuse sweating Headache Weakness Blurred vision Nausea Muscle cramps Possible loss of consciousness If unconscious, Call a Medical Emergency Loosen clothing Move victim to cooler space If faint, lower head to knees Fluid/electrolyte replenishment Transport to medical treatment facility

• • • • •

Heat Stroke SEVERE Medical Emergency!!

Caused by shutdown of the body’s cooling system

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Body “gives up” on trying to cool down Symptoms

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Skin--Hot, Flushed, Dry

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Sweating ceases

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Pulse fast and strong Breathing deep Vomiting, Cramps, Twitching Will go into shock Can and WILL be FATAL if body is not cooled IMMEDIATELY by any means possible!

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Ice, alcohol, remove clothing, fans, etc.

Transport to Medical Treatment right away!

QUESTIONS?

Questions??