Hemorrhoids

116

EXPOSURE-RELATED INJURIES

The opportunity to enjoy the scenic splendor of the great outdoors is one of the major attractions of traveling, but it comes with a risk of injury due to exposure. The following are some of the primary dangers.

HYPERTHERMIA

In temperate weather, the human body naturally regulates its core temperature to an average of 98.6°F (37°C), but an individual’s actual core temperature varies with daily sleep-wake cycles (and women’s monthly cycles) as well as from individual to individual.

Hyperthermia results when the body’s temperature is elevated well above normal, which can occur in an environment with a temperature much higher than the normal range. The lower limit of hyperthermia is poorly defined. Heat stroke can occur when a person’s core temperature exceeds 104°F (40°C). Extreme ultramarathon runners, however, have been known to sustain core temperatures as high as 108°F (42°C).

The state of acclimatization (adaptation to repeated or sustained high temperatures), the arduousness of any physical work and the relative humidity of the environment influence how a person’s core temperature responds to heat. Heat stress associated with high relative humidity increases dramatically at higher air temperatures. The body’s cooling mechanism relies not on sweating but on the evaporation of sweat—and the higher the relative humidity, the more evaporation is inhibited. To account for the effect of relative humidity, in 1990 the U.S. National Weather Service developed a heat index scale as a calibration of the apparent temperature.

Immersion in water represents the highest level of relative humidity. Because immersion prevents evaporative cooling and because of water’s huge capacity for holding heat, water temperatures that exceed 97°F (36°C) are not well tolerated by humans, particularly if they must also exert themselves. Recreational scuba divers rarely experience water temperatures that high, so hyperthermia typically occurs during surface- or land-based activities.

Symptoms: The signs and symptoms of hyperthermia vary according to the severity of the condition. Heat-stress disorders can be divided into the following five categories: