Heatstroke is a less common but far more serious threat to health than heat exhaustion. In about 20 percent of heatstroke cases, heatstroke is fatal. In heatstroke, the sweating mechanism breaks down completely; the body is unable to rid itself of excess body heat. The body's temperature may rise as high as 105F. Prolonged, high body temperatures can cause failure of the brain, kidneys, and liver.

The early symptoms of heatstroke are similar to those of heat exhaustion-headache, nausea, and dizziness. At first, the victim's breathing is deep and rapid; but, as the symptoms progress, breathing becomes shallow, almost absent. The skin appears flushed, dry, and very hot. The pupils are constricted to a pinpoint; the pulse is fast and strong. It is extremely important that you recognize the differences between heat exhaustion and heatstroke. HEATSTROKE IS A TRUE LIFE-AND-DEATH EMERGENCY.

The most important first-aid treatment for a heatstroke victim is to lower the victim's body heat. Move the victim to a cool place. Douse the victim with cold water. Remove as much of the victim's clothing as possible to allow free flow of air over the body to promote cooling. If the victim is conscious, give him/her cool water to drink. Transport the victim to a medical facility as quickly as possible.

So far, we have discussed heat-related problems and the first-aid treatment for heat stress. However, you will be much better off if you learn what you can do to prevent heat stress.

PREVENTION

In spaces where heat stress is likely to occur, it is difficult to lower temperatures. Therefore, preventing heat stress-related conditions is the goal. Monitoring conditions that bring about heat stress and controlling the crew's exposure to high-heat and high-humidity conditions reduces the chances of heat stress.

Some of the factors that cause heat stress are as follows:

Unnecessary heat and humidity sources

Steam leaks

Damaged insulation

Report these types of conditions so they can be corrected. Vents and exhaust blowers should be adjusted to maintain proper air circulation.

On board ship, spaces are ventilated by ductwork connected to supply (intake) and exhaust blowers. These blowers (or fans) are driven by two-speed electric motors. Exhaust fans have a greater air-moving capacity than supply fans. Unless personnel are otherwise directed, supply and exhaust ventilation fans are set to the SAME speed. It is important that you understand the need to MAINTAIN FLOW. If you do not MAINTAIN FLOW, the following could happen to you. A watch stander in a hot space sets the supply blower to high speed and then stands under the outlet.

Usually, you can tell whether the speed of the vent blowers for a space is set correctly by how hard it is for you to open or shut the doors to the space. For example, if a door opens outward and it is hard to close, then the space has a POSITIVE pressure. This means that the supply vent is probably set on high speed, and the exhaust vent is set on low speed.

Another common problem with shipboard ventilation systems is improper care of system filters. Filters are installed at the intake of the supply blowers to prevent dust and dirt from entering the ship. Cleaning these falters is considered to be routine maintenance. If, however, filter cleaning is neglected or is poorly done, the temperature of shipboard working and living spaces increases because there is a reduced flow of coding air. Spaces considered to be heat-stress areas should contain a heat-stress monitor to measure the heat-stress conditions.

On an individual level, wear clothing so there is some air circulation between the clothing and your body. Whenever you perform heavy physical labor, eat lightly and take a rest period before resuming heavy exertion.

The Navy has established strict space environmental monitoring requirements for heat-stress conditions. These heat-stress surveys, together with strict exposure limit standard tables, control the amount of time a person may remain in certain high-temperature and high-humidity conditions before being REQUIRED to go to a cool place and rest. For more information about heat injury, you should refer to Shipboard Heat Stress Control and Personnel Protection, OPNAVINST 5100.20 (series), and Navy Occupational Safety and Health (NAVOSH) program Manual for Forces Afloat, OPNAVINST 5100.19 (series).

Heat illnesses and injuries are primarily caused by the loss of body fluids and salts. Preventing these illnesses and injuries centers on replacing body fluids and salts, monitoring the environment, and controlling exposure. For example, in a hot environment, fluids must be replaced ounce for ounce. Therefore, when you are sweating heavily, increase your water intake proportionately. Meals provide salts to replace those lost through sweating. Therefore, if you work in a high-heat and high-humidity environment, you should eat well-balanced meals at regular intervals, salted to taste. You should get at least 6 hours of sleep every 24 hours. Wear clean clothing made from at least 35 percent cotton. Do NOT wear starched clothing. Do NOT drink commercially prepared electrolyte supplements in place of water. Do NOT take salt tablets unless specified by medical personnel. Do NOT drink alcoholic beverages, because alcohol depletes the level of fluids in the body.

Remember, the effects of heat stress are cumulative (add up). Once you have heat cramps, heat exhaustion, or heatstroke, you are twice as likely to experience a heat stress-related incident; your body has an increased sensitivity to heat. Your awareness of the factors that contribute to heat stress and their prevention, as well as your strict adherence to established exposure limits, will help prevent your becoming a victim of heat stress.