Royal Army College

Lesson Overview

Earlier lessons guarded against the disease carried by water, food, waste, and unclean living. This lesson turns to a different enemy: the environment itself, which disables a force not by infection but by the plain effects of heat, cold, sun, and wet. Environmental injury sits beside disease as one of the great causes of non-battle loss. Whole armies have been broken by heat in the desert and cold in the mountains, and almost every such casualty was preventable. As with disease, the aim is to stop the casualty from happening.

A clear boundary governs this lesson. The course teaches the prevention and recognition of environmental injury: how to keep heat and cold from harming the body, and how to read the warning signs when they begin to. It does not teach treatment, which is taught in full by the Combat First Aid course (Lesson 06, environmental injuries) and, for cold injury, by the Cold-Weather Operations and Survival course. Where this lesson brings a member to the point of recognising a casualty, it hands them on. Any clinical care belongs to those courses and to qualified medical staff, not to this reading.

This matters to our force in particular. The Royal Kaharagian Army is a small, lightly armed home-defence force whose work is humanitarian as often as military: hard labour out of doors in whatever weather the day brings, clearing after a storm, carrying for the stranded, standing a long welfare line. A member felled by the weather is a pair of hands lost to the people counting on them. Preventing it is part of the duty of care the force owes its own members and those it serves.

By the end you will be able to explain why the environment is a major cause of non-battle injury, describe how the body keeps its heat in balance, set out the prevention of heat illness and cold injury step by step, recognise the warning signs of each, name where their treatment is taught, describe sun protection and the lesser environmental hazards, and explain the leader's responsibility for protecting the team. This is the knowledge layer; the practical measures are reinforced and certified in person.

Key Terms

Environmental injury: harm done to the body by field conditions, chiefly heat, cold, sun, and wet, rather than by disease or enemy action; a major cause of non-battle injury.
Heat balance: the body's continual trade of heat with its surroundings, which it must keep balanced to hold its core temperature within a narrow safe band; heat is lost through four routes (radiation, conduction, convection, evaporation) and gained from hard work and a hot environment.
Heat illness: the range of harm done by heat and dehydration, from heat cramps and heat exhaustion to the emergency of heat stroke.
Dehydration: losing more water than is taken in, chiefly through sweat in the heat; it cripples the body's cooling and is the commonest cause of heat illness.
Acclimatisation: the body's gradual adjustment to working in heat or cold, built over a couple of weeks, which greatly lowers the risk of injury.
Work-and-rest discipline: the leader's regulation of how hard a team works and how often it rests in heat or cold, to keep its members within safe limits.
Cold injury: harm done by cold, in freezing form (frostbite) and non-freezing form (such as trench foot) from prolonged wet and cold; its treatment is taught in the Cold-Weather Operations and Survival and Combat First Aid courses.
Hypothermia: the dangerous fall of core temperature when the body loses heat faster than it can make it; the whole-body counterpart to frostbite's local injury, brought on by cold made worse by wet, wind, and exhaustion.
Heat stroke: the most dangerous heat illness, a failure of the body's heat control with confusion and a soaring temperature; a medical emergency requiring immediate cooling and evacuation.
Buddy-check: members watching one another, in heat or cold, for the warning signs a person may not feel in their own body, so harm is caught early.
Carbon monoxide: a colourless, odourless, poisonous gas given off when fuel is burned, which can build up and kill in an enclosed space where a stove, heater, or engine is run for warmth.

The environment as an enemy

It is easy to treat heat and cold as mere discomfort, the background against which the real work is done. They are not. The body holds itself within a narrow temperature band, and the field is forever pushing it out: heat and hard work drive it up, cold and wet drag it down, and at either edge the body begins to fail. Campaign history is full of forces wrecked by the environment as thoroughly as by any enemy. Like disease, environmental injury comes from known causes and is kept off by known measures.

It builds quietly and can strike suddenly, which is why prevention rules this lesson. A member working hard in the heat loses water faster than they feel, and may be well on the way to collapse before they think anything is wrong. A member standing wet and still in the cold may not notice their feet failing until the harm is done. By the time the casualty is plain, the prevention has already been missed. So the measures here are kept as discipline, applied in advance and from above, and recognising the early warning signs matters enormously: the warning caught early is the casualty prevented.

How the body keeps its heat in balance

Every measure in this lesson is no more than a way of helping the body hold its temperature steady, so it helps to understand how it does that. The body works best within a narrow band of core temperature. It is always making heat, from food burned and above all from working muscles, and always shedding heat to its surroundings; health lies in keeping the two in balance. Make or take in more heat than you shed, and the core climbs and heat illness threatens. Shed more than you make, and it falls and cold injury threatens.

The body trades heat with the world by four routes. Knowing them shows why the prevention measures work.

   FOUR ROUTES BY WHICH THE BODY GAINS OR LOSES HEAT

   Radiation     Heat passes as warmth between the body and
                 nearby surfaces and the sky. Sun and hot
                 ground radiate heat INTO the body; on a cold
                 clear night the body radiates heat away to
                 the open sky.

   Conduction    Heat passes by direct contact. The body loses
                 heat fast to cold, wet ground it sits or lies
                 on, and to water, which draws off heat far
                 faster than air.

   Convection    Moving air (or water) carries heat away from
                 the skin. Wind strips warmth from the body;
                 this is the windchill that makes cold worse,
                 and why a breeze cools in heat.

   Evaporation   When sweat dries off the skin it carries away
                 a great deal of heat. This is the body's MAIN
                 way of cooling in the heat; it needs water to
                 do it and dry air to work well.

Two rules follow that govern the whole lesson. In the heat, the body sheds the heat of work and a hot day mainly by sweating and letting it evaporate, which costs water steadily; if that water is not replaced, or the air is too humid for sweat to dry, the cooling fails and the core climbs. That is why water is the first measure against heat. In the cold, the body must hold the heat it makes, and it loses heat fastest to wet (far quicker than to dry air) and to wind; a wet, wind-exposed member chills even well above freezing. That is why "keep warm and, above all, dry" is the first rule against cold. Humidity, wind, sun, and wet ground are the very levers by which heat and cold do their harm, and the prevention that follows works those levers in the body's favour.

Heat illness, and how to prevent it

Heat illness is the body's failure to shed the heat that hard work and a hot environment load onto it, made worse by the loss of water and salt in sweat. Its prevention rests on a few plain disciplines.

The first and most important is drinking enough water, because water is how the body cools itself. A member working hard in the heat can lose more than a litre an hour without feeling proportionate thirst, for thirst lags behind the body's real need and is no safe guide; drink only when thirsty and you are already behind. So drink regularly and in good amount, before thirst forces it: a cup at a time at short intervals rather than occasional floods, with a little extra before hard work. Cool water is taken up faster than warm. The plainest self-check is urine colour: pale and plentiful means well watered; dark, scant, and infrequent is a warning to drink more. There is a ceiling as well as a floor. Match drinking to loss, for floods of plain water far beyond need do their own harm.

The second measure is to replace salt through food, not tablets. Sweat carries out salt as well as water, but ordinary field meals contain ample salt, so the rule is simply to eat all meals, even when heat and fatigue dull the appetite; the member who skips meals is starving the body of the salt it sweats away. Salt tablets are not taken. A tablet draws water from the body to dilute it and so worsens the very dehydration it is meant to cure, can sicken the stomach, and is given only on a medical instruction this course does not supply.

The third measure is to pace the work against the heat of the day. Hard labour is itself the largest source of the heat that overwhelms the body, so make less of it when the day makes most: set heavy tasks, where the mission allows, for the cooler morning and evening, and give the hottest hours to lighter work and rest. Rest in shade where any can be found, which spares the body the sun's radiated heat. This is the heart of heat discipline, set out in the guide below.

The fourth measure is to acclimatise gradually. The body adjusts to working in heat over a couple of weeks of building exposure, learning to sweat sooner and lose less salt, and the acclimatised member works far more safely than one fresh to it. The unacclimatised member, newly come from a cooler place or returned from a spell away, must be built up by degrees, given lighter loads and shorter spells at first and watched more closely, not thrown straight into a full day's labour.

To these add the plain helps of shade and ventilation: resting out of the sun; clothing worn loose at the neck, wrists, and lower legs so air moves over the skin and sweat evaporates; and skin covered against the sun, which prevents burns and keeps the cooling skin sound. Add too a watchful eye on those at higher risk, who reach their limit sooner and must be set easier and watched harder.

   MEMBERS AT HIGHER RISK OF HEAT ILLNESS
   (set easier work, watch more closely)

   - The unwell, especially with fever, vomiting, or
     diarrhoea (already short of water)
   - The recently sunburned or with a heat rash
     (the skin's cooling is hampered)
   - The worn-out and short of sleep
   - Anyone who has had a heat injury before
   - The not-yet-acclimatised, lately from a cooler place
   - Anyone who has taken alcohol in the last day
     (it dehydrates and clouds judgement)

Above all this is a matter the leader carries. Before the task they get the forecast, see that ample water is brought and sited within reach, arrange the work for the cooler hours where the mission allows, and place leaders where they can watch a dispersed team. They set and enforce the work-and-rest discipline; ensure members actually drink, often and in small amounts, and check the canteens hold water and not some other drink; see the team eat its meals for the salt; and watch for the first signs of heat affecting anyone. A team left to regulate itself will push on too long and drink too little, because the work calls and the danger is hidden. The leader's discipline of water and rest is what keeps it safe.

   HEAT: A WORK, REST, AND WATER GUIDE
   (a simple guide for the leader; the body's needs
    rise as the day grows hotter and the work harder)

   How hot the    EASY WORK         HARD WORK
   conditions     e.g. light        e.g. carrying loads,
   feel           tasks, steady     digging, fast marching,
                  movement          heavy clearance

   Warm           Work steadily;    Short rests each hour;
                  drink to thirst   drink ~1 cup every
                  and beyond        20 min; watch for tiring

   Hot            Rests each hour   Frequent, longer rests
                  in shade; drink   in shade; drink ~1 cup
                  steadily          every 15-20 min; rotate
                                    members off the heaviest
                                    work

   Very hot       Lighter work      Stop hard work in the
                  only; long        worst heat if the task
                  rests in shade;   allows; rest in shade;
                  drink steadily    keep drinking; watch
                                    every member closely

   Drink small amounts often, not floods. Cool water is best.
   Rest means light activity in shade if any can be found.
   Keep skin covered against the sun; eat all meals for salt.
   Carrying body armour or a heavy load adds to the heat load:
   ease the work and watch the more.

Recognising heat illness

A member and a leader must be able to recognise heat illness as it begins, so it can be acted on before it worsens. The illness runs along a rising scale, from mild warnings to true emergency, and reading where a casualty stands on it is what this course teaches. Picture the scale as a climbing core temperature: the higher it climbs, the graver the illness.

   THE RISING SCALE OF HEAT ILLNESS

   core temperature climbing  ----------------------------->

   HEAT CRAMPS        HEAT EXHAUSTION        HEAT STROKE
   painful muscle     body labouring:        heat control
   cramps; salt and   sweating, pallor,      FAILS: confusion
   water lost;        headache, weakness,    and soaring heat;
   member otherwise   dizziness, nausea,     a MEDICAL
   alert; temperature faintness; near the    EMERGENCY
   near normal        body's limit

   a WARNING          a CLEAR DANGER         the EMERGENCY
   to act on early    cool, rest, rehydrate  cool and evacuate
                      at once                without delay

Heat cramps are at the milder end: painful cramps of the working muscles, often in legs and arms and sometimes the abdomen, brought on by the loss of salt and water in heavy sweating; the member is otherwise alert and their temperature near normal. Cramps are a plain message that the body is running short, a signal to stop, rest, and take water before worse follows.

Heat exhaustion is the body labouring to cope: heavy sweating, pale clammy skin, headache, weakness and tiredness, dizziness, often nausea, and the member may feel faint or actually faint, especially on standing after exertion. It is a clear danger that the body is near its limit and must be cooled, rested in the shade, and given water at once. Recognise it as the warning it is, and treat it as the Combat First Aid course teaches.

Heat stroke is a medical emergency, the gravest environmental injury in this lesson. It is the failure of the body's heat control, marked above all by a change in the mind and a soaring temperature: confusion, disorientation, drowsiness, strange or irrational behaviour, perhaps collapse, with the body very hot to the touch. The skin may be hot and dry or still sweating; either way the confused, altered state and high temperature set heat stroke apart from heat exhaustion. It can come on suddenly, even from what looked like exhaustion moments before, and it kills quickly if not acted on. It demands immediate cooling and urgent evacuation to medical care. A member who recognises a comrade's confusion and soaring heat must know this is the emergency, not someone merely overcome by the day, and raise the alarm at once. The treatment, the cooling and the handling of the casualty, is taught in full by the Combat First Aid course; this lesson's task is to fix the recognition.

   THE LINE TO HOLD IN YOUR MIND

   PREVENTION and the WARNING SIGNS          |   THE EMERGENCY
   (this lesson)                             |   (hand on at once)
                                             |
   Drink steadily, pace work and rest,       |   HEAT STROKE:
   acclimatise, eat meals, use shade,        |   confusion and a
   watch the team.                           |   soaring temperature.
   Catch heat cramps and heat exhaustion     |   Cool and evacuate;
   early; cool, rest, and rehydrate.         |   treated by Combat
                                             |   First Aid and
   This is where prevention keeps the team.  |   medical staff.

Cold injury, in brief

Cold injury is taught in full, prevention and treatment alike, by the Cold-Weather Operations and Survival course, and its first aid by the Combat First Aid course, so it is kept brief here and the member is referred to those courses for the whole of it. What this lesson fixes is the shape of the danger, the early warning, and the few measures every member must hold whatever the season.

Cold harms the body in two distinct ways. The first is whole-body cooling, or hypothermia: when the body loses heat faster than it can make it, its core temperature falls, and a chilled, shivering, clumsy, confused member is one whose whole body is failing. Like heat stroke, hypothermia can come on in conditions that do not look extreme, for wet and wind carry heat off so fast that a soaked, wind-blown member can chill dangerously well above freezing, and in cold water within minutes. The second is local cold injury to the extremities, in two forms. The freezing form is frostbite, the flesh itself freezing in hard cold, striking soonest the exposed parts: fingers, toes, ears, nose, and cheeks. The non-freezing form, of which trench foot and immersion foot are the type, comes not from freezing but from prolonged exposure to wet and cold, the feet kept wet, cold, and still too long, and it can occur well above freezing. This makes it the more likely danger in a cold, wet climate, where wind and water steal heat without a frost.

Prevention is summed up in one rule, with a few parts.

   COLD: THE RULE AND ITS PARTS

   KEEP WARM AND, ABOVE ALL, DRY

   - Dress in LAYERS, and adjust them: open up or shed a
     layer before hard work makes you sweat, add layers
     when you stop. Wet from sweat chills as surely as rain.
   - Keep clothing DRY; change wet or damp clothing and
     wet socks for dry as soon as you can.
   - Mind the EXTREMITIES: dry socks changed often for the
     feet, gloves or mittens for the hands, a hat and cover
     for the head, ears, and face. Much body heat is lost
     through an uncovered head.
   - Stay OUT OF THE WIND and OFF cold, wet ground; wind and
     wet steal heat fastest.
   - KEEP MOVING gently when you can, to make heat; if you
     must stay still, work the toes, feet, fingers, hands.
   - EAT and DRINK: the body needs fuel to make heat, and it
     dehydrates and chills in the cold as well as the heat.
   - AVOID alcohol and tobacco: alcohol makes the body lose
     heat faster, and tobacco cuts the blood flow to the
     skin and extremities that keeps them from freezing.

Layering is the heart of keeping warm and dry, because it lets a member match clothing to effort: open or shed layers before hard work brings the sweat that soaks and then chills, and build them back the moment the work stops. Whole-body warmth, by clothing worn this way and kept dry, guards against hypothermia and frostbite. Keeping the extremities, the feet above all, clean and dry, with dry socks changed often, guards against the non-freezing injury, which is why the foot care of the previous lesson and the Navigation and Fieldcraft course matters here too. Staying out of wind, off wet ground, fed, and watered completes the guard, and avoiding alcohol and tobacco removes two needless ways the body is robbed of warmth and circulation.

A particular caution belongs here, because it has killed people who did everything else right. Burning fuel of any kind, a stove, a heater, an engine, gives off carbon monoxide, a gas that cannot be seen, smelled, or tasted and that poisons and kills in an enclosed space, the more readily in the cold when a shelter is shut tight for warmth. The rule is firm: never run a stove, heater, or engine for warmth in a closed shelter, tent, or vehicle without good ventilation, and never sleep in or beside a running engine or a burning fire in an enclosed space. The warmth bought that way can cost a life, and the gas gives no warning.

The early signs are read on the exposed parts and on the member's whole bearing. Skin that turns pale, white, or waxy and loses feeling, and feet or hands grown numb and cold, signal local cold injury: warm and dry the member without delay. Shivering that will not stop, clumsiness, slurred speech, stumbling, or confusion signal the whole body chilling toward hypothermia, the graver emergency, to be acted on at once. As with heat, the leader carries the responsibility: planning for the cold, seeing members have dry kit, spare socks, warmth, and hot food and drink, rotating those standing still in the cold out before they chill, and setting up the buddy-check, because a member often cannot feel the harm in their own numbed flesh.

   THE BUDDY-CHECK (heat and cold alike)

   Members watch one another for what a person may not
   feel or notice in themselves:

   In the HEAT     a comrade who has stopped sweating, gone
                   pale or unsteady, grown quiet, confused,
                   or stopped drinking.

   In the COLD     a comrade's pale, white, or waxy patches
                   of skin; numb fingers, toes, ears, nose;
                   shivering, stumbling, or muddled speech.

   The harm caught in a comrade early is the casualty
   prevented. Ask, look, and act before it worsens.

The recognition fixed here is enough to know cold injury is starting. The detail of prevention and the whole of treatment belong to the Cold-Weather Operations and Survival and the Combat First Aid courses.

Sunburn and sun protection

The sun harms the body in its own right, and sunburn is more than a discomfort. Burned skin is damaged skin: it hampers the body's cooling and so raises the risk of heat illness, it can blister and become a route for infection, and bad burns can put a member out of action as surely as a minor wound. It is also entirely preventable. The defences are plain. Cover the skin against the sun with clothing, the surest guard. Use sun cream of a good protection factor on skin that must stay exposed, renewing it after heavy sweating or a soaking, with a lip balm to match. Wear a hat or headgear to shade the head and neck. Protect the eyes with sunglasses, for strong sunlight can injure the eyes as it does the skin, the more so where glare is doubled by reflection off snow, water, or pale ground. On snow this reflected glare can bring on snow blindness, a painful temporary loss of sight, so sun discipline is owed in the bright cold as much as in the heat. Sun protection is part of heat discipline, since the burned member is the more liable to heat illness, and part too of the leader's duty to see the team protected.

The effect of wet and poor weather

Wet and poor weather do their own harm, short of the named injuries. Damp itself, apart from cold, wears at the body: skin kept wet softens, breaks down, and infects more readily, which is how blisters and the foot rot of the previous lesson begin, while wet clothing and bedding chill the body and rob it of rest and warmth. So keeping the body, clothing, and bedding dry, and insulated from wet ground, defends against more than cold alone, and the chance to dry out, change into dry kit, and warm and rest is itself a health measure a leader plans for, not a comfort to defer. Poor weather of every kind grinds a team down over days, sapping warmth, breaking sleep, soaking kit, and lowering resistance so that disease and cold injury take hold the more easily. The guard is the same steady discipline kept up rather than let slide: stay as dry and warm as conditions allow, get rest and hot food, watch one another, and treat recovery as the necessity it is. Weather that never quite becomes a crisis can still empty a team's strength if it is merely endured instead of managed.

Other environmental hazards in brief

Beyond heat, cold, sun, and wet, the field holds other hazards. Contaminated ground is one a unit may meet, especially in relief work after a disaster, where flooding and ruin can foul the ground with sewage, waste, fuel, or chemicals. Treat doubtful ground as suspect, keep skin and especially broken skin out of contact with it, wash after contact, and keep food, water, and sleeping places clear of it, drawing on the water and waste lessons of this course. Dangerous animals and plants are the other standing caution: a unit working out of doors and in disturbed ground may meet biting or stinging creatures, snakes among them, and plants that poison or sting on contact. The prevention is watchfulness and avoidance: look before reaching into cover or under debris, keep limbs covered where the risk is high, do not handle or eat what is not known to be safe, and leave creatures alone rather than provoke them. The detail belongs to fieldcraft and to the next lesson, on pests and the prevention of disease, which carries the biting and disease-bearing creatures further. The governing habit is the same as for the greater hazards: watch the conditions of the field and prevent their harm before it is done.

In Practice: The Work Party in the Heat

A section is set to clear debris from a flooded settlement on a hot, still day, hard labour under a strong sun. How the work is run will decide whether all of them finish it on their feet, and the leader treats heat as the real adversary. Beforehand they get the forecast, see that ample water is carried to the site and set within easy reach, and plan the heaviest clearing for the cooler morning. From the start they enforce a work-and-rest discipline, working the section in spells with regular rests in what shade can be found rather than driving it straight through. They see that each member actually drinks, often and in small amounts, not waiting on thirst, and check the canteens hold water and not some other drink; and they have the team eat its meals for the salt. Knowing two of the section came lately from cooler postings and are not yet acclimatised, the leader sets them easier and watches them closer, and has everyone cover their skin and use sun cream. The section is set to buddy-check, watching for the comrade gone pale, quiet, or unsteady.

Midway through, one member grows pale, sweating, headachy, and unsteady. The leader recognises heat exhaustion for the warning it is and pulls them at once into the shade to be cooled, rested, and given water, watching for any slide into the confusion that would mark heat stroke, ready to act on the Combat First Aid course's teaching and call for help. It did not come, because the warning was caught early. The section finishes the task, tired but well, and the settlement is helped rather than given fresh casualties to tend. Run without that discipline, the work party would have started losing members by the afternoon, and the heat, not the flood, would have done it.

Check Your Understanding

Why does the lesson call the environment a major cause of non-battle injury, and why does it stress that environmental injury builds quietly and can strike suddenly? Name the four routes by which the body trades heat with its surroundings, and explain why water is the first defence against heat and dryness the first against cold. What boundary does the lesson keep between prevention and recognition on the one hand and treatment on the other?
Set out the main measures for preventing heat illness, and the part the leader plays, including the work-and-rest discipline and who counts as higher-risk. Describe the warning signs of heat exhaustion and the signs that mark heat stroke as the emergency it is, and say where the treatment of each is taught.
Distinguish hypothermia from local cold injury, and the freezing form from the non-freezing form, and give the single rule and its parts that prevent them, including the buddy-check and the carbon-monoxide caution. Why is sunburn more than a discomfort, why must the eyes be protected in bright cold as well as heat, and how is the harm of wet and poor weather prevented?

Reflection (write a short paragraph): This lesson makes the leader's regulation of work, rest, water, warmth, and dryness the heart of protecting a team from heat and cold, because the danger is hidden and a team left to itself will push too far, and it sets a buddy-check over the team because a member often cannot feel the harm in their own body. Think of a hot or cold field or relief task you might lead or be part of. Which warning sign of heat or cold injury would be easiest to miss in yourself or a tired comrade, and what would the leader need to put in place, in advance, to keep the whole team within safe limits rather than waiting for a casualty to appear?

Summary

The environment, through heat, cold, sun, and wet, is a major cause of non-battle injury; it builds quietly and can strike suddenly, so this lesson teaches prevention and recognition, while treatment belongs to the Combat First Aid and Cold-Weather Operations and Survival courses and to qualified medical staff. For a small humanitarian home-defence force, preventing it is part of the duty of care owed to its own members and to those it serves.
The body holds core temperature steady by balancing the heat it makes against the heat it trades through four routes: radiation, conduction, convection, and evaporation. In heat it cools mainly by sweating, which needs water; in cold it loses heat fastest to wet and wind. So water is the first defence against heat, dryness the first against cold.
Heat illness is prevented step by step: drink water steadily before thirst forces it and watch urine colour; replace salt by eating meals, never by tablets; pace work against the heat of the day with lighter work in the worst heat; acclimatise gradually; use shade and ventilation; ease and watch the higher-risk; and the leader plans the task, regulates work and water, and watches the team.
Heat illness runs along a rising scale of climbing core temperature: heat cramps; then heat exhaustion (heavy sweating, pallor, headache, weakness, dizziness, faintness); then heat stroke, a medical emergency marked by confusion and a soaring temperature, demanding immediate cooling and evacuation.
Cold injury is whole-body hypothermia or local injury in freezing (frostbite) and non-freezing (trench foot, from prolonged wet and cold) forms; the rule for all is keep warm and, above all, dry, by layering, dry kit and dry socks, covering the extremities, staying out of wind and off wet ground, eating and drinking, the buddy-check, and a firm caution against carbon monoxide from a stove, heater, or engine run for warmth in a closed space. Early signs are pale, waxy, numb skin and cold extremities, and the shivering, clumsiness, and confusion of hypothermia.
Sunburn is damage that hampers cooling and invites infection, prevented by covering the skin, sun cream, headgear, and eye protection, the eyes guarded against glare in bright cold as well as heat. Damp and poor weather wear the body down and are met by keeping dry, warm, and rested. Contaminated ground and dangerous animals or plants are met by watchfulness and avoidance. Throughout, protecting the team from heat and cold is a leader's responsibility, by the discipline of work-and-rest, hydration, warmth, dryness, and watchfulness for the warning signs.

Heat, Cold, and the Environment