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 being in hot outdoors working for an extended period.
High humidity aggravates the problem, since it reduces the efficiency of sweating. Sweating is how our bodies to attempt to cool down; when the air is full of water (high humidity), sweat doesn’t evaporate.
Signs of Dehydration
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:
- Mild dehydration: Increased thirst, dry lips and discomfort.
- Moderate dehydration: Nausea, sunken eyes, increased body temperature, difficulty in concentrating.
- Severe dehydration: Weakness; mental confusion; rapid, weak pulse (more than 100 at rest); cold hands and feet; rapid breathing; blue lips; confusion; lethargy and muscle spasms.
Dehydration is accompanied by weight loss.
Dehydration measured as weight loss
Mild dehydration occurs with less than 3% loss of body water. At this point, we start feeling thirsty, but we have already lost quite a bit of water. At 5% water loss, a 180-pound man will have lost 9 pounds.
The signs of dehydration will get more severe with each percentage loss of body water after that.
Dehydration can lead to death at more than 10% weight loss caused by water loss. At the severe stage, fluids must be replaced by intravenous application.
|
Weight loss caused by dehydration |
| Initial weight |
3% |
5% |
8% - |
11% |
| 180 lbs |
5.4 lbs |
9 lbs |
14.4 lbs |
19.8 lbs |
| 145 lbs |
4.4 lbs |
7.3 lbs |
11.6 lbs |
16 lbs |
To replenish and prevent dehydration adequately, extra fluids must be drunk all day when working outdoors in hot climates, before the first signs of thirst. To replace all fluids lost, 2 cups of fluids are needed for every pound lost.
Preventing Dehydration
- Drink before, during and after being outdoors. Hydrate thoroughly the day before if you can. Try to consume 4 to 8 fluid ounces of water every 15 to 30 minutes during heavy activity in hot climates. Although the temperature of the replacement fluid is not critical, fluids at room temperature may replace lost fluid in cells faster than chilled fluids. Plain water or electrolyte solutions are good choices. Avoid caffeine and alcohol; these diuretics will cause your body to lose water. Most of the dark soft drinks contain caffeine.
- Hyperhydrate just before going out. Drinking 1½ to 3 cups of cold water or an electrolyte solution can help delay the process of dehydration.
- Check with your doctor about the medications you are taking. Antihistamines and some blood pressure medications decrease sweating. Since these and other drugs may cause dehydration or interfere with cooling, check with your doctor to see if you can avoid their use for several days before being outdoors doing physical labor, or if you should avoid being outside in the heat.
- Dress in light-colored fabrics that breathe. Use clothing that reflects light and that is of loose, lightweight material. Tightly woven clothing does not allow heat to pass through. Some synthetic clothing made today is designed to allow sweat and heat to be pulled from the skin.
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.
Dehydration 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 laboring outdoors in the heat.