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Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of summer heat.Among the large continental family of natural hazards, only the cold of winter-not lightning, hurricanes, tornadoes, floods, or earthquakes-takes a greater toll. From 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the disastrous heat wave of 1980, more than 1,250 people died.And these are the direct casualties. No one can know how many more deaths are advanced by heat waves or how many diseased or aging hearts surrender that under better conditions would have continued functioning.North American summers are hot; most summers see heat waves in one section or another of the United States. East of the Rockies, heat waves tend to combine both high temperature and high humidity although some of the worst have been catastrophically dry.NOAA's National Weather Service Heat Index Program considering this tragic death tollthe National Weather Service (NWS) has stepped up its efforts to alert more effectively the public and appropriate authorities to the hazards of heat waves. Based on the latest research findings, the NWS has devised the "Heat Index" (HI), (sometimes referred to as the "apparent temperature"). The HI, given in degrees Fahrenheit, is an accurate measure of how hot it really feels when relative humidity (RH) is added to the actual air temperature.How Heat Affects the Body HumanHuman bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and, as the last extremity is reached-by panting, when blood is heated above 98.6 degrees.The heart begins to pump more blood, blood vessels dilate to accommodate the increased flow, and the bundles of tiny capillaries threading through the upper layers of skin are put into operation. The body's blood is circulated closer to the skin's surface, and excess heat drains off into the cooler atmosphere. At the same time, water diffuses through the skin as perspiration. The skin handles about 90 percent of the body's heat dissipating function. Sweating, by itself, does nothing to cool the body, unless the water is removed by evaporation, and high relative humidity retards evaporation. The evaporation process itself works this way: the heat energy required to evaporate the sweat is extracted from the body, thereby cooling it. Under conditions of high temperature (above 90 degrees) and high relative humidity, the body is doing everything it can to maintain 98.6 degrees inside. The heart is pumping a torrent of blood through dilated circulatory vessels; the sweat glands are pouring liquid, including essential dissolved chemicals, like sodium and chloride, onto the surface of the skin...To read more go to:
As in the days of Noah...
