The U.S. Air Force has adopted a variation of its camouflage type work uniform that features knee-length shorts for maintenance personnel who spend a lot of time working outside, often eight hours or more, in very hot (45 Celsius/115 Fahrenheit) weather. With reflections from the aircraft and the concrete airstrip, that can get as high as 55 (130 Fahrenheit). Three airbases in Arizona, Nevada and Florida have adopted the shorts as an option for airmen working outside in hot weather and the reaction was favorable. Some European nations had already adopted this practice for personnel operating in airbases with similarly hot temperatures.
The use of knee shorts options for military work uniforms is relatively rare. The British used such shorts until the end of World War II. These “combat shorts” were common for British and Commonwealth troops in North Africa and other areas where the daytime weather was over 40 degrees Celsius. This practice continued after World War II in some commonwealth nations.
The U.S. adopted it for some hot weather white dress uniforms. In other cases shorts were allowed for American troops on guard duty (wearing the khaki off duty uniform) in Louisiana bases, where it was very hot and humid. Earlier in the 20th century, the Americans adopted similar attire, with pith helmet, for tropical bases.
Using shorts for a combat uniform reduced heat-related injuries but also produces sunburned legs for the light-skinned and more scrapes and scratches for everyone during combat operations. Also, troops in the desert needed to carry with them a pair of long pants for night time, when the desert temperature drooped to at least half the daytime level and it was often quite chilly. In tropical climates, troops often wore civilian clothes, including shorts, while off duty. During World War II American sailors on smaller ships (destroyers) could often informally adopt shorts and officers tolerated it unless there were admirals or senior staff officers about. This practice still occurs in some hot climates where combat zone troops wear combat uniform pants converted (with knife or scissors) to shorts. In a combat zone officers often consider it good for morale.
In the late 20th century technology made long pants more tolerable in hot weather because of new fabrics that let body heat escape while also providing protection from direct sunlight in tropical climates. Shorts are still popular off duty, but while at work the extreme heat is no longer the problem it once was. The new U.S. Air Force policy is an option and many of the maintenance personnel stuck with their long pants for most outside work.