Karen Overstreet, Roy, Heli J. | 3/29/2005 11:25:18 PM
The combination of heat, humidity and hard work can spell trouble for people cleaning up after a disaster, especially if they don't usually work outdoors. We usually think of dehydration happening to athletes engaged in sports activities, but it can also affect farm workers, construction workers, gardeners and anyone not used to working in the hot outdoors for an extended period.
High humidity aggravates the problem, since it reduces the efficiency of sweating. Sweating is how our bodies attempt to cool down; when the air is full of water (high humidity), sweat doesn’t evaporate.
Dehydration can start before we get thirsty. Increased thirst is a response to a loss of body water, but to stay hydrated, we need to start replacing lost fluids before first signs of thirst. A good sign of proper hydration is the output of large volumes of clear, dilute urine. These are some signs of dehydration in various stages:
It is possible to adapt to the heat through a process called heat acclimatization, where the body makes adjustments to promote better cooling in hot environments. Sweat becomes more dilute, and your body learns to hold on to salt. The threshold at which sweating begins is lowered, and the sweat rate is increased. These changes take time to complete fully -- about 10 days of high activity in the heat -- and will work only if you are well hydrated.
Dehdyration can be brought about in other situations. It can occur during illness when there is severe vomiting and diarrhea, and it may be caused by diabetes, kidney disease, excessive use of diuretics, liver disease resulting in accumulation of fluid in the abdominal cavity, inflammation of the abdominal cavity resulting in fluid accumulation and burns. People who are predisposed to dehydration should not expose themselves to greater risk by doing physical labor outdoors in the heat.
When you are outdoors in a hot environment, make sure to carry water with you and drink every few minutes, even when you don't feel thirsty. You can prevent dehydration that way.