Chapter 17: Stress

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Physical Stress

Objectives: By the end of this section, participants will recognize heat and cold stress, their problems, treatments and preventions.

Why this section is important: Heat and cold stresses are a leading cause of workplace illness and lowered productivity.

Heat Stress Cold Stress

Heat Stress Characteristics
Category & Clinical Features	Predisposing Factors	Treatment	Prevention

Heatstroke
Hot, dry skin, usually red & mottled. Rectal temp. > 40.5°C (104°F) Confusion, loss of consciousness, convulsions.	Sustained exertion in heat by unacclimatized workers. Lack of physical fitness and/or obesity. Recent alcohol intake. Dehydration. Individual susceptibility. Chronic cardiovascular disease	Immediate and rapid cooling by immersion in chilled water with massage or by wrapping in wet sheet with vigorous fanning with cool dry air. Avoid overcooling. Treat shock if present. Seek professional assistance.	Medical screening of workers. Acclimatization for 5-7 days by graded work and heat exposure. Monitoring workers during sustained work in severe heat.

Heat Syncope (Fainting)
Fainting while standing erect and immobile in heat	Lack of acclimatization	Remove to cooler area Rest in relaxed position	Acclimatization Intermittent activity

Heat Exhaustion
Fatigue, nausea, headache, giddiness Skin clammy and moist; complexion pale, muddy, or hectic flush May faint on standing Oral temperature normal or low, but rectal temp. usually elevated (99.5-101.3 F) Urine volume small, highly concentrated or less concentrated	Sustained exertion in heat Lack of acclimatization Failure to replace water lost in sweat	Remove to cooler environment Rest in relaxed position Administer fluids by mouth Keep at rest until urine volume indicates that water balances have been restored	Acclimatize workers using a breaking-in schedule for 5-7 days Provide ample drinking water at all times

Heat Cramps
Painful involuntary muscle contractions	Not well known but water loss and/or salt loss is suspected	Water replenishment Intra-venous infusion under extreme conditions	Acclimatization Sufficient water

Skin Eruptions (Heat Rash, "prickly heat")
Profuse tiny raised red vesicles (blister-like) on affected areas Pricking sensations during heat exposure	Unrelieved exposure to humid heat with skin continuously wet from unevaporated sweat	Mild drying lotions Skin cleanliness to prevent infection	Cool sleeping quarters to allow skin to dry between heat exposures

Anhidrotic Heat Exhaustion
Skin does not sweat on heat exposure Gooseflesh appearance	Chronic (weeks or months) of constant exposure to climatic heat with previous history of extensive heat rash and sunburn	No effective treatment available for anhidrotic areas of skin; recovery of sweating occurs gradually on return to cooler climate	Treat heat rash and avoid further skin trauma e.g., sunburn Provide periodic relief from sustained heat

Transient Heat Fatigue
Temporary impaired performance of sensory and motor skills	Exacerbated in unacclimatized worker	Not indicated unless accompanied by other heat illness	Acclimatization and training for work in the heat

Chronic Heat Fatigue
Chronic reduced performance capacity	Temperate workers in tropical latitudes	Medical treatment for serious causes, normal relief upon returning home	Orientation on life in hot regions

Hypothermia

Definition: The lowering of body temperature to unsafe levels. Characterized by a body temperature < 97.5 °F.

Symptoms:

Uncontrollable shivering and the sensation of cold.

Slow, irregular heartbeat, weak pulse and low blood pressure.

Severe shaking or rigid muscles.

Vague or slow slurred speech.

Memory lapses and incoherence.

Drowsiness, apparent exhaustion, and fatigue after rest.

Cool skin.

Slow and irregular breathing.

Pain in the extremities.

Frostbite

Damage to tissues from freezing of blood cells (i.e., < 30° F). Independent of hypothermia.

Degrees of Frostbite:

Frost nip (incipient frostbite): sudden blanching or whitening of skin. Tissue freezes without blistering or peeling.

Superficial frostbite: skin has waxy or white appearance and is firm to touch but underlying tissue is normal. Tissue freezes with blistering and peeling.

Deep frostbite: tissues are cold, pale and solid. This is very serious and usually requires amputation. Tissue freezes with tissue death.

Cold Stress Prevention

To minimize cold stress:

Workers should dress as warmly as possible using layered clothing.

Careful attention should be used to wearing gloves when handling metal equipment.

At the discretion of the safety officer, work tours should be limited to minimize exposure to the cold.

Warm shelter should be made available for workers during breaks. Vehicles for warm shelter pose the risk of carbon monoxide exposure.

Do not provide alcoholic beverages.

The safety officer should carefully observe workers for signs of hypothermia and frostbite.

Thought Questions:

Can heat stress cause permanent physical damage? Can cold stress cause permanent physical damage?

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Suggested Frequency of Physiological Monitoring for Fit and Acclimatized Workers^a
Adjusted Temperature^a	Normal Work Attire^c	Impermeable Attire
> 90°F	After each 45 minutes of work	After each 15 minutes of work
87.5 - 90°F	After each 60 mins of work	After each 30 minutes of work
82.5 - 87.5°F	After each 90 minutes of work	After each 60 minutes of work
77.5 - 82.5°F	After each 120 minutes of work	After each 90 minutes of work
72.5 - 77.5°F	After each 150 minutes of work	After each 120 minutes of work
(a) For work levels of 250 kilocalories/hour. (b) Calculate the adjusted air temperature (a adj °F) = ta °F + (13 X % sunshine). Measure air temperature (ta) with a standard mercury-in-glass thermometer, with the bulb shielded from radiant heat. Estimate % sunshine by judging what % time the sun is not covered by clouds that are thick enough to produce a shadow. (100% sunshine = no cloud cover and a sharp, distinct shadow: 0% sunshine = shadows) (c) A normal work ensemble consists of cotton coveralls or other cotton clothing with long sleeves and pants. Source: Occupation Safety and Health Guidance Manual for Hazardous Waste Site Activities (NIOSH/OSHA/USCG/EPA, 1985).