Heat and Humidity

Sustaining Health & Performance in the Heat

High temperatures, overexposure to the sun, inadequate water consumption and over-exertion may result in one of the following:

Dehydration

The human body is highly dependent on water to cool itself in a hot environment. A safe and adequate supply of water must be available at all times to every soldier. SOLDIERS MUST ONLY DRINK WATER FROM APPROVED SOURCES. Fresh water may be contaminated by minerals through which the water flows, or contain bacteria or parasites that may cause DNBI.

Countermeasures to Problems with Water Consumption or Dehydration:

1. Ensure all soldiers drink adequate quantities of (preferably cool) water.
2. Drink water regularly – even when not thirsty. Thirst is not an accurate indication of the body’s need for water. Drink about one quart each hour (or more depending on extreme conditions and workload) or enough to maintain urine the color of weak lemonade (dark urine indicates the body’s need for water).
3. Ensure water supplies have been processed by Reverse Osmosis Water Purification Units (ROWPU) and properly chlorinated to 2.0 ppm. The chlorine residual for ROWPU treated water must be maintained at 1.0 ppm in the unit area unless otherwise designated by the medical authority.
4. If non-approved fresh water (from lakes, rivers, streams) must be used IN A LIFE OR DEATH SITUATION, disinfect the water using one of the following methods:
   • Calcium hypochlorite at 5.0 ppm for 30 minutes
   • Clor-Floc^TM or iodine tablets per label instructions
   • Boil water at a rolling boil for 5-10 minutes
   • Add two to four drops of ordinary chlorine bleach per quart of water and wait 30 minutes
5. Avoid storing bottled water in direct sunlight (due to possible bacterial growth).
6. Soldiers in armored vehicles, MOPP, and body armor need to increase water intake.
7. Monitor local weather conditions closely, especially the rapidly changing WBGT.

Sunburn

Caused by overexposure of the skin to ultraviolet (UV) radiation of the sun – occurs rapidly in the desert. Sand, rocks, and other desert surfaces reflect sunlight from the ground, and may result in sunburn to the nostrils or chin. Severe sunburns are disabling and may make soldiers more susceptible to other types of heat injuries.

Countermeasures:

1. Use unscented sun block for skin (applying to all exposed face, skin, and neck) and lip balm with SPF 15 or higher, and sunglasses will protect soldier’s skin and eyes from UV radiation.
2. Wear uniforms properly.
3. While on guard duty, avoid standing in direct sunlight; regularly rotate soldiers with duties requiring exposure to extreme temperatures for long periods (i.e., guard mount, POL point, observation posts, and maintenance personnel).

Heat Cramps

Heat cramps are characterized by painful cramps of the muscles, usually the legs and abdomen, caused by an imbalance (too much or too little) of electrolytes in the body as a result of excessive sweating. Soldiers suffering from heat cramps may complain of muscle cramps, heavy sweating, and extreme thirst.

Countermeasures:

1. Seek immediate medical attention for all heat injuries.
2. Move the soldier to a cool, shady area or air conditioned building or vehicle and loosen clothing.*
3. Slowly give large amounts of water (cool water if available).
4. Watch the soldier; continue to provide water if the soldier accepts it.

* When in a chemical environment, DO NOT loosen/remove clothing.

Heat Exhaustion

Heat exhaustion is a preventable condition caused by the loss of water through sweating without adequate fluid replacement. Soldiers suffering from heat exhaustion may experience heavy sweating with pale, moist, cool skin; headache, weakness, dizziness; and/or loss of appetite.

Countermeasures:

1. Seek immediate medical attention for all heat injuries.
2. Move the soldier to a cool, shady area or air conditioned vehicle or building and loosen clothing.*
3. Pour water on the soldier and fan to permit cooling effect; if available apply ice or ice packs.
4. Have the soldier slowly drink at least one full canteen of water.
5. Elevate soldiers legs.
6. If possible, soldier should not participate in strenuous activity for the remainder of the day.

* When in a chemical environment, DO NOT loosen/remove clothing.

ABOUT SALT… In addition to water, the body’s supply of sodium chloride (or salt) is also lost in sweat. Salt lost through sweat should be replaced only by consuming prescribed amounts of rations. Soldiers should NOT take salt tablets, or consume additional salt with meals, unless strictly controlled according to medical advice. Field rations usually contain very high salt concentrations, therefore, soldiers should maintain a higher water intake when consuming these meals. Excess intake of salt should be avoided as it may cause increased thirst and/or nausea.

Heat Stroke

Heatstroke is a MEDICAL EMERGENCY that may result in death if treatment is delayed. Soldiers suffering from heatstroke should be evacuated immediately to a medical facility. Soldiers who have worked in a very hot, humid environment for a prolonged time, and have not consumed an adequate amount of water are susceptible to heatstroke that is caused by failure of the body’s cooling systems. Soldiers suffering from heatstroke may experience sweating (flushed, red, hot, dry skin) [NOTE: sweating is not an indication of a less serious heat injury – soldiers who are sweating may still be experiencing heatstroke], weakness, dizziness, confusion, headaches, seizures, nausea, rapid respiration, and weak pulse. Irritable, combative or irrational behavior sometimes precedes heatstroke. Unconsciousness and collapse may occur suddenly.

Countermeasure to prevent heatstroke:

1. HEATSTROKE IS A MEDICAL EMERGENCY – seek immediate medical attention.
2. Move the soldier to a shady area or air conditioned vehicle or building and loosen clothing (remove outer and/or protective clothing if the situation permits).*
3. Start cooling the soldier IMMEDIATELY; immerse in cool water (or pour water on the soldier).
4. Fan to cool.
5. Massage extremities and skin to increase blood flow to body areas (aiding the cooling processes).
6. Elevate soldier’s legs.
7. If conscious, have the soldier slowly drink one full canteen of water.
8. Monitor soldier for development of conditions that may require performance of necessary basic lifesaving measures such as clearing the airway, mouth-to-mouth resuscitation, and/or treatment for shock.
9. Evacuate ASAP to a medical facility continuing emergency procedures during transport.

* When in a chemical environment, DO NOT loosen/remove clothing.

Acclimatization

Acclimatization to heat is necessary to permit the body to reach and maintain maximum efficiency in its cooling process. Ideally, a period of about two weeks should be allowed for acclimatization, with progressive degrees of heat exposure and physical exertion. Soldiers and unit leaders should note that although acclimatization strengthens heat resistance, there is no such thing as total protection against the effect of heat. The table below presents guidelines for unit leaders, medical planners, and soldiers to follow. Pre-acclimatization may be achieved by gradually increasing physical activity in a hot environment.

Unit leaders, commanders, and soldiers should note these very basic guidelines for preventing heat injuries:

• Consider water a tactical weapon.
• Drink water frequently even if not thirsty. Drinking should be required and monitored by command.
• Use unscented sunscreen and lip balm (SPF 15 or higher), and sunglasses.
• Place something between soldiers and the hot ground.
• Limit movements.
• Wear uniform properly: wear T-shirt; roll sleeves down; cover head; and protect the neck with a scarf or similar item to protect the body from hot, blowing winds and sunlight.
• Resting in the shade, quietly, fully clothed, not talking, keeping mouth closed, and breathing through the nose will decrease the body’s water requirement.
• Perform heavy work in the cooler hours of the day, such as early morning or late evening, if possible. If working or travelling during these periods, watch for increased activity of wildlife (i.e., snakes and insects) during cooler hours and in the evenings.
• Identify soldiers with previous heat injuries.
• If in an emergency situation and water is scarce, do not eat. Find water by looking for animal trails that may lead to water holes, flocks of circling birds, or look (or dig) for water in areas supporting plants or grasses. Disinfect water as stated previously.

Fluid Replacement Guidelines for Warm Weather Training
(Applies to average acclimated soldier wearing BDU, Hot Weather)

Heat Category	*WBGT Index oF	Easy Work		Moderate Work		Hard Work
		Work/Rest	Water Intake (qt/hr)	Work/Rest	Water Intake (qt/hr)	Work/Rest	Water Intake (qt/hr)
1	78 – 81.9	NL	½	NL	¾	40/20 min	¾
2 (Green)	82 – 84.9	NL	½	50/10 min	¾	30/30 min	1
3 (Yellow)	85 – 87.9	NL	¾	40/20 min	¾	30/30 min	1
4 (Red)	88 – 89.9	NL	¾	30/30 min	¾	20/40 min	1
5 (Black)	> 90	50/10 min	1	20/40 min	1	10/50 min	1

Information courtesy of LTC Mark A. Lovell, MD, MPH, Program Manager Disease and Injury Control, Directorate of Clinical Preventive Medicine, U. S. Army Center for Health Promotion and Preventive Medicine

• The work/rest times and fluid replacement volumes will sustain performance and hydration for at least 4 hours of work in the specified heat category. Individual water needs will vary ±¼ qt/hr.
• NL = no limit to work time per hour.
• Rest means minimal physical activity (sitting or standing), accomplished in the shade if possible.
• CAUTION: Hourly fluid intake should not exceed 1½ quarts.
• Daily fluid intake should not exceed 12 quarts.
• Wearing body armor adds 5°F to WBGT Index.
• Wearing MOPP overgarment adds 10°F to WBGT Index.

Easy Work	Moderate Work	Hard Work
·  Walking on Hard Surfaces at 2.5 mph, <= 30 lb. Load ·  Weapon Maintenance ·  Manual of Arms ·  Marksmanship Training ·  Drill and Ceremony	·  Walking on Hard Surfaces at 3.5 mph, < 40 lb. Load ·  Walking on Loose Sand at 2.5 mph, no Load ·  Calisthenics ·  Patrolling ·  Individual Movement Techniques, i.e. low crawl, high crawl ·  Defensive Position Construction ·  Field Assaults	·  Walking on Hard Surfaces at 3.5 mph, >= 40 lb. Load ·  Walking on Loose Sand at 2.5 mph with Load

Sponsored by the U.S. Army Center for Health Promotion and Preventive Medicine, the Army National Guard, and the Office of the Chief, Army Reserve. Copyright 2006

Thanks for the share LB!