Filed under: Environment
Sweat is a critical function when you’re performing in hot environments. As your body absorbs heat from the environment, your nervous system activates sweat glands to release sweat. The moisture on your skin then evaporates, taking heat away from your body and cooling you off.
Protective clothing impedes the evaporation of sweat and the heat exchange between you and the environment, a condition known as “evaporative resistance.” This means that the exposed parts of your body will cool off more quickly than the parts that are covered, but they are also more prone to insect bites. Reports from Marines and National Park employees feeling “excessive heat” and a loss of sweating sensations after applying moderate to high amounts of DEET to their skin brought the safety of this insect repellent into question.
In a recent study, researchers found that when 33% DEET lotion is applied according to military protocol, it does not interfere with sweat production or other physiological responses. Nor does it interfere with the evaporation process necessary for cooling to take place. Researchers concluded that 33% DEET can be worn safely during military and occupational activities performed in hot, insect-infested environments. Similar studies have found oil- or alcohol-based repellents may increase core temperature by reducing sweat evaporation rate but do not affect sweat production. The military-approved form of DEET is polymer-based.
You can watch a YouTube video about the science behind the study.
DEET is considered by the EPA to be a toxic pesticide. It should be used with caution and as directed. More information about DEET, its uses, and warnings can be found on the EPA fact sheet. As of 2004, DEET was considered safe for use on children older than two months of age. Specific information on its use and effect on children can be found in the EPA TEACH chemical summary.
Pentagon scientists are hoping to build special gear designed to turn divers into veritable Aquamen (and Aquawomen). Although it’s still in the research phase, the new system would protect divers from the adverse effects of diving too deep or surfacing too fast. Sensors would read and adjust to a diver’s physical signs as well as help control levels of nitric oxide to prevent the decompression sickness known as “the bends.” When a diver ascends too quickly, bubbles form inside the body, which can block the blood vessels in the spinal cord and disrupt the nervous system. It can be very painful and can lead to joint pain, paralysis, and even sudden death if a diver is not careful.
The new diving gear will be a portable and versatile system that can potentially serve for use in other special operations as well as for civilian divers. This system will have to be designed for the most extreme combat dive profiles, which sometimes require a 35,000-meter free-fall from an aircraft, diving 200 feet below the surface for at least two hours, surfacing, and immediately diving again, followed by continued protection after being picked up in an unpressurized aircraft. This is one of DARPA’s most recent Small Business Innovation research proposals for 2013.