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DEFINITION OF ADEQUACY OF CLOTHING IN COLD CLIMATES Paul Siple 1. Adequacy for General Activity at Dry Ambient Air Temperatures Belov That of the Body " A standard definition of adequacy is difficult to posit, because it in- volves a corrleation of activity, time, and severity of exposure. Each of these elements is composed of many variables. After careful examination of clothing which in the past has been considered adequate, the following definition is here- by proposed: Adequate clothing for temperatures between 86°F. and 14°F. shall provide a comfortable equilibrium at the temperature of the environment for men who are standing in the shade with wind at approximately 5 miles per hour.1 Normally, men who have this protection will be obliged to ventilate their clothing or to remove surplus items when they exercise at higher rates of activi- ty. If they sit idly or try to lie down without other protection, their clothing will not be adequate indefinitely but only for a certain period of time; although, some additional protection will be furnished them if the wind is reduced to a minimum.2 The necessary clo values for comfort at any activity and temperature are indicated in Graph No. 1, with the activity of standing marked by the heavy line. To determine whether clothing is adequate for any part of the world for a given period, it is proposed to take the monthly average of the daily mean tempera- ture of the environment. Actual day and night temperatures will vary around this within a certain range. Men may find it necessary to exercise more at the mini- mum nighttime temperatures and may be overdressed during the heat of the day, par- ticularly if they are exposed to direct solar radiation. While the monthly aver- age of the daily mean is not most representative temperature over a period of 24 hours, the adequacy of clothing may be more precisely determined than is possible for military purposes by taking the average maximum daytime temperature for use in day and average minimum nighttime temperature for night use. Climatic zone maps have been developed, showing the range of temperature for any part of the world for each month of the year. The mean temperature of each zone has a range of 18°F. from the warmest to the coolest part of the zone. For clothing purposes,'the temperature range of one clo may be said to approximate the temperature range of one climatic zone, for activities which include those of truck driving, standing still, and standing still but with occasional movements as in guard duty. However, since the deficit of i clo may cause considerable loss of equilibrium, these zones should be subdivided to give the half clo range. The correlation of climate zone clo values and activities are shown more precisely in Table No. 1 and Graph No. 4. Prom the graph, it will be obvious that at the higher ambient temperatures the men may have a lower activity while still remaining in 1. Since at present no suit which provides sufficient mobility is adequate indefinitely for temperatures below l4°F., either the activity must be increased or the duration of exposure shortened. 2. For laboratory correlation, it may be noted that protection for three hours tolerance time for men sitting absolutely still at a work rate of 50 Kg. Cals/MShr. is approximately equivalent to indefinite protection for men standing at 75 Kg. Cals/M2/hr. at the same temperature. 65
