Clothing Selection

1. Clothing Selection OP 110

2. Physiological Considerations • Outdoor travelers must select clothing that will allow them to maintain a stable body core temperature, retain or dissipate excess body heat and moisture, and protect themselves from the elements. This concept is known as thermal regulation. • Clothing must: • Permit the body to maintain a core temperature slightly above or below 98.6o F (37o) for proper physical and mental functioning. • Allow water vapor to dissipate from the body’s surface. • Protect the wearer from the elements (sun, wind, rain, & snow) • Protect the wearer form common injuries such as sunburn, blisters, insect bites, skin irritation from poisonous plants or briars, etc.

3. Thermal Regulation • The body is constantly trying to maintain a constant body temperature. This process is called thermal homeostasis. Loss of heat in the backcountry can be caused by 5 different possible principles. • Use the acronym RRECC to help remember them. Respiration, Radiation, Evaporation, Conduction and Convection.

4. RRECC • Respiration – Breathing. During this process, heat loss occurs both through evaporation (taking dry air into the moist lungs) and convection (warming cold air taken into the lungs). You can counter this by decreasing the level of activity or by breathing though an item of clothing (Scarf, neck warmer, face mask) • Radiation – Is the transfer of thermal energy from one object’s surface to the surface of another object without physical contact and without any warming of the space between the two. Example – Exposed skin like the head and neck radiate heat. To counter this in cold weather use proper clothing. Make sure to cover the head, neck, wrists, and hands.

5. RRECC 3. Evaporation – Occurs when perspiration or sweat on the skin’s surface passes form a liquid state to a vapor, causing a cooling of the skin. To counter evaporation you should wear clothing that is breathable and allows moisture to be wicked away form the body and/or decrease the level of activity.

6. RRECC 4. Conduction – Occurs when fast-moving (warm) molecules hit slower-moving (cool) molecules and transfer energy in the form of heat to the slower molecules. Heat loss occurs when the skin comes in contact with cooler objects. Example – sit on a cold rock. Counter conduction by sitting on an insulated pad will prevent heat loss or wearing gloves. 5. Convection – is the exchange of heat between hot and cold objects by physical movement in a liquid or gas. Example – wind travels through our clothing and blows away heat trapped between the skin and clothing. The same thing occurs when immersed in moving water. Counter convection in cold environments by wearing wind proof clothing, flaps over zippers and drawstring closures. In hot climates wear loose clothing designed with optimal ventilation.

7. RRECC

8. Clothing Considerations • Clothing must not be selected based on style and looks. Clothing should be selected based on its function. • Consider wearing natural, earth tone colors and not brightly colored clothing. Exception would be when hunting. • Contemporary clothing can be expensive and serve only as a status symbol.

9. General Principles 1. Clothing should be roomy and comfortable, allowing for reasonable freedom of movement. 2. Clothing should not hinder circulation. Elastic cuffs around the wrist and ankles should be avoided. 3. Clothing must meet thermal regulation needs. (keep user warm or cold depending on the conditions)

10. General Principles 4. Clothing should keep you dry when required. 5. Clothing should provide protection. 6. Clothing must be durable and dependable. 7. Clothing should be relatively easy to maintain and launder. 8. Clothing should be lightweight and compressible 9. Clothing should be properly designed for its function. (e.g.. External garments should have large pockets that are conveniently located and can be securely fastened.