>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 in accordance with daily sleep-wake cycles (and with monthly cycles in the case of women), as well as from individual to individual.
>Hyperthermia — which means your body temperature is elevated well above normal — can result when you're 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 someone's core temperature exceeds just 104°F (40°C). However, extreme ultramarathon runners have been known to sustain core temperatures as high as 108°F (42°C).
>How your core temperature responds to heat is strongly influenced by your state of acclimatization (that is, your adaptation to repeated or sustained high temperatures), the arduousness of any physical work you're doing, and the relative humidity of the environment. The 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 U.S. National Weather Service developed a heat index scale — that is, 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. Water temperatures that high are not commonly experienced by recreational scuba divers. As a result, hyperthermia typically occurs during surface or land-based activities.
>Signs and symptoms: (Symptoms of a disease are subjective indications that can be detected by a patient, such as pain or fatigue, while signs are objective indications that can be detected by a doctor, such as temperature or pulse.) The signs and symptoms of hyperthermia vary, according to how severe the condition is. Heat-stress disorders can be divided into the following five categories:
>* Heat edema: Edema means the accumulation of excess fluid in the body's tissues and cavities; heat causes the blood vessels to dilate (expand), so fluid tends to pool in the arms and legs, resulting in a condition known as peripheral edema.
>* Heat cramps: Heat, especially in combination with exercise, can cause a loss of water and electrolytes in the body, resulting in muscle cramps and spasms, especially in the calves, arms, and abdomen.
>* Heat syncope: Syncope means fainting, or a temporary loss of consciousness; when heat leads to dilation of the peripheral blood vessels, another effect, besides peripheral edema, can be a drop in blood pressure and a decline in the amount of blood flowing to the brain, which can result in fainting.
>* Heat exhaustion: Heat exhaustion is caused by dehydration — the loss of water and electrolytes from the body; it is characterized by headache, nausea or vomiting, low blood pressure, dizziness, fatigue and temporary loss of consciousness — though victims' mental status remains normal and their rectal temperature remains below 104°F (40°C).
>* Heat stroke: A more severe form of heat exhaustion, heat stroke is characterized by a pronounced change in mental status, severe headache, nausea or vomiting, loss of consciousness and often cessation of sweating — and a rectal temperature exceeding 104°F (40°C).
>Treatment: Victims should be removed from the overheated environment as soon as signs or symptoms of hyperthermia are apparent. The greater the magnitude of the malady, the more aggressive the efforts to cool the victim must be.
>* Heat edema is easily resolved with rest and elevation of the extremities.
>* Heat cramps can be managed with ice massage (rubbing an ice cube on the affected area for five minutes at a time), stretching, and oral fluids.
>* Heat syncope can be managed by placing victims in a resting, supine position (lying on their back, face up) with their extremities mildly elevated, and by monitoring their vital signs (blood pressure, heart rate, temperature and respiration).
>* Heat exhaustion requires monitoring victims' vital signs and core temperature, administering electrolyte-rich fluids (such as Gatorade), and ensuring rest and cooling. If victims become dizzy or their blood pressure drops when they stand up, intravenous fluids may be required.
>* Heat stroke requires urgent cooling, monitoring of victims' vital signs and core temperature, intravenous fluids, and rest.
>Cooling measures can be as simple as finding a seat in the shade for victims of minor heat maladies, but as drastic as immersion in ice water for victims of heat stroke. Immediate cooling is critical in serious cases. Even though ice-water baths are uncomfortable, they have proven to be safe and effective for heat stroke victims. If a victim's signs and symptoms do not begin to abate after treatment has been instituted, especially if the individual appears to be getting warmer, seek medical aid immediately.
>Prevention: For divers, water temperatures high enough to cause hyperthermia are typically not a problem during a dive. More common stressors are exposure to hot surface conditions, particularly when divers are wearing insulated suits (especially drysuits) designed to protect them in cool or cold underwater conditions, as well as the physical work involved in carrying dive equipment on land.
>Thus preventive measures for divers include adequate hydration, sufficient shade, and the ability to rest and adjust or remove attire as required. Adequate hydration requires continual awareness of your water intake whenever you're in hot environments — and especially in hot and humid environments. The need for good hydration is increased for divers who experience a diuretic effect (that is, promoting the production of urine) from wearing tight wetsuits and/or from immersion. The concentration of your urine can be influenced by changes in your diet, activity level and thermal status, but passing nearly clear, colorless urine several times per day is generally considered evidence of adequate hydration. If your urine volume is reduced or its color darkens, you should drink more water (or other stimulant-free fluids).
>Preventive measures for nondivers are similar: maintaining good hydration, staying in the shade outdoors or in air-conditioned spaces indoors, pacing your activity level, and dressing appropriately (in light colors, for example). In conditions of extreme heat, drinking electrolyte-rich fluids may be required.
>Hypothermia — which means your body temperature drops well below normal — can result when you're in an environment with a temperature much lower than the normal range. Hypothermia is defined as a core temperature below 95°F (35°C). Exposure to a cold environment results in your body losing heat faster than it's producing heat — at a rate that is affected by the temperature gradient between your skin and the environment, the heat capacity of the environment (this is much greater for water than for air), the presence of wind or water movement (such as tides or currents, both of which hasten cooling), your body composition (a higher lean-to-fat ratio and a lower body mass-to-surface area ratio both hasten cooling), and how much protective clothing you're wearing.
>Hypothermia often occurs due to immersion in cold water, because water conducts heat away from the body 20 to 27 times faster than air. The shock if you're suddenly immersed in water colder than 59°F (15°C) — without thermal protection — can cause an inhalation gasp response, which can induce you to inhale water. The stress response also triggers an extremely rapid heart and breathing rate. In addition, cold shock may be accompanied by pain and mental disorientation, which can lead to fear and panic.
>Good thermal protection — a wetsuit, drysuit or other survival-type gear — will dramatically lessen the immediate effects of immersion in cold water, but heat loss will still occur over time.
>The rate at which your body produces heat can be increased by exercise or shivering, but if you are immersed in water and are wearing little or no thermal protection, swimming actually increases your exposed surface area and thus elevates the rate at which your body heat is transferred to the water. In general, you can maintain your core temperature by swimming only in water that's warmer than 75°F (24°C). An unprotected swimmer's core temperature will usually drop in water colder than that. An inability to continue swimming (a condition known as swimming failure) typically develops more rapidly than one expects in cold water.
>If you are immersed in cold water and not wearing thermal protection, but have buoyancy support (such as a life jacket) and there is a chance of rescue, you should remain still in a position that minimizes your exposed surface area. Pulling your knees together and up to your chest is known as the heat-escape-lessening position (HELP), or the rescue position, and provides improved protection of the body's high-heat-loss areas: the armpits, groin, chest and thighs.
>Immersion-related hypothermia can also occur in relatively warm or even tropical waters as a result of slow body cooling over time. This may happen if you're in water as warm as 84°F to 91°F (29°C to 33°C) if you're not wearing any thermal protection. In such circumstances, you may not be aware of the slow heat drain for some time.
>Hypothermia can, of course, also occur in surface or land settings. The same factors — including the temperature of your environment, the presence of wind, and how appropriately you're clothed for the conditions — are key in whether, and how soon, you're likely to develop hypothermia. Similarly, even a slightly cool temperature can result in cold stress, depending on an individual's age, health status, body-fat ratio and body mass.
>Signs and symptoms: (Symptoms of a disease are subjective indications that can be detected by a patient, such as pain or fatigue, while signs are objective indications that can be detected by a doctor, such as temperature or pulse.) The signs and symptoms of cold stress vary, according to how severe the condition is. The following chart details the signs and symptoms of various gradations of hypothermia.
>Treatment: Individuals with mild hypothermia will be awake, conversing lucidly, complaining about the cold and probably shivering. Assuming no other injuries, mildly hypothermic victims can be rewarmed with a variety of passive or active techniques, with minimal risk of complications. If travelers suffer hypothermia in a remote setting, many rewarming options, particularly more aggressive and invasive techniques, will likely not be available; nevertheless, rescuers must do what they can to protect victims from further injury. The essential first step is, if possible, to remove any wet clothing and replace it with a dry insulating inner layer and a windproof outer layer, including over the head. Shivering can provide effective rewarming in cases of mild hypothermia. If victims feel comfortable exercising, that can also increase the rewarming rate. Exercise will slightly increase afterdrop — a continued decline in victims' core temperature even after their removal from the cold stress — but this is typically not problematic in cases of mild hypothermia. Fully alert and cooperative victims of hypothermia can also drink warm liquids. These deliver negligible amounts of heat but help offset associated dehydration and impart a sense of comfort. Most beverages are suitable — but avoid alcohol, as it can compromise victims' awareness and exacerbate dehydration and vasodilatation (expansion of the blood vessels). Food can improve victims' energy reserves, but it's not a critical immediate need for well-nourished victims.
>Individuals with moderate hypothermia will be conscious but may be confused, apathetic, or uncooperative and may have difficulty speaking. Moderate hypothermia demands more caution, since cardiac arrhythmias (disturbances of the heart's rhythm) can be expected. Gentle handling and active rewarming techniques — such as heated blankets, forced-air rewarming, and heated and humidified breathing gas — are all desirable, if they're available. Exercise is not recommended for those with moderate hypothermia, due to its potential for increasing afterdrop and to victims' compromised physical coordination. Afterdrop can raise the risk of physiological collapse, especially during or shortly after a rescue from immersion-related hypothermia. Gentle handling, including keeping victims supine (lying on their back, face up), with their heart and head at similar levels, and completely at rest will reduce the risk of collapse. Use the most effective alternatives at hand when rewarming. Take care to insulate victims from the ground or other cold surfaces (for example, consider using a wetsuit as an insulated "mattress"). A warm-water bath is another good option for victims of moderate hypothermia — but it's essential to physically support them throughout their transfer to the bath and their immersion. The initial bathwater temperature should be lukewarm, definitely not more than 105°F (41°C), to minimize the sensation of burning that victims will likely experience. After immersion, the water temperature can be progressively increased to no more than 113°F (45°C). If hot water isn't available, moderately hypothermic individuals can be rewarmed with chemical packs or electric pads; to avoid burns, however, they should never be applied directly to the skin.
>Individuals with severe hypothermia may be unconscious, may have a slowed heart rate and respiration, or may even appear dead, with no detectable heartbeat. Look very carefully for signs of life, such as breathing, movement, or a pulse in the neck (in the carotid artery). Assess their breathing first, then their pulse, for a period of at least one minute to confirm either respiratory arrest or pulseless cardiac arrest, which would necessitate cardiopulmonary resuscitation (CPR). If hypothermia is caused by cold-water immersion, death usually results from loss of consciousness and subsequent drowning. If drowning precedes hypothermia, successful resuscitation is unlikely. But if victims evidence breathing or movement, that means their heart is still beating, even if at a slow rate. Spending sufficient time to check for the existence of a pulse is essential. If there is either breathing or a heartbeat, external heart massage (also known as chest compression) is not needed. For the unconscious hypothermic individual, the main goals are to maintain adequate blood pressure and respiration and to prevent further heat loss. Severe hypothermia leaves victims susceptible to cardiac arrest, so extremely gentle handling — putting them in a supine position with their head and heart at the same level, fully supporting them, and keeping them from all physical activity — as well as aggressive, often invasive rewarming strategies are essential. Cardiac arrhythmias may result from severe hypothermia — and even from rewarming a severely hypothermic individual. Basic life support takes precedence over efforts to rewarm a victim.
>If there are no signs of life in a hypothermic individual, begin CPR and make arrangements for emergency transport to the nearest medical facility. Rewarming victims of severe hypothermia is almost impossible in the field. But it is essential to protect them against further heat loss. If CPR is required, it should be continued, if possible, until medical assistance is obtained. There have been successful resuscitations after prolonged CPR, in part because of some naturally protective effects of hypothermia. In occasional cases, victims who appear clinically dead, due to marked decline in their brain and cardiovascular function, are fully resuscitated, with their neurological functions intact. Learn more about CPR from Alert Diver online . However, the outlook is poor for adults who have a core temperature below 82°F (28°C), have been immersed for more than 50 minutes, have life-threatening injuries, or are more than four hours from definitive medical care.
>In hypothermic individuals, discontinue CPR only under these conditions:
>* The person is successfully resuscitated.
>* The rescuers become too fatigued to continue.
>* The person has been completely rewarmed but is still unresponsive to properly administered CPR.
>* A medically qualified individual arrives at the scene and, after examining the victim, declares the person dead.
>The following steps are advised following a cold-water immersion incident:
>* Determine the cause of the immersion to reduce risk to the rescuers.
>* Handle the victim as gently as possible.
>* Assess the victim for responsiveness and normal breathing (and be aware of the increased risk of cardiac arrest while the victim is being handled and removed from the water).
>* If breathing is absent, begin CPR and continue it until medical personnel arrive.
>* Give the victim as much oxygen as possible.
>* Determine the cause of the immersion.
>* If any injury is suspected, support and immobilize the victim's neck as well as possible.
>* Arrange transport to a medical facility.
>* Prevent further heat loss.
>* Rewarm as needed and as the situation allows.
>The protocol for aiding victims of nonimmersion-related hypothermia are the same, aside from the steps related specifically to immersion.
>Prevention: Preventing hypothermia if you plan to swim or dive in cool or cold water requires preparation. It is essential that divers understand the proper use of protective garments to conserve their body heat and control heat loss. Most divers will benefit from wearing thermal protection in water cooler than 80°F (27°C). Significant thermal stress can be expected in water colder than 75°F (24°C). Divers should ensure that they have the proper protective equipment, as well as training and experience in how to dive safely in cool or cold water. Immersion in cold water without thermal protection results in incapacitation much faster than one expects. An additional aspect of preparation involves training and readiness in case a rescue (or self-rescue) is necessary; rapid action greatly increases the likelihood of a successful outcome in such an instance.
>Preventing hypothermia if you plan to engage in surface or land-based activities requires wearing appropriate clothing for the conditions; dressing in layers and wearing a hat to prevent body heat from escaping from your head are especially beneficial. It is also important to stay dry and to avoid overexertion, which can cause you to sweat and get chilled if the sweat cools before it evaporates.
>Signs and symptoms: (Symptoms of a disease are subjective indications that can be detected by a patient, such as pain or fatigue, while signs are objective indications that can be detected by a doctor, such as temperature or pulse.) The onset of AMS symptoms varies according to the altitude, your rate of ascent, and your individual susceptibility to the disease. A slow ascent is more likely to allow your body to acclimate, by establishing a more rapid spontaneous breathing rate to make up for the decreased oxygen in the atmosphere. Symptoms usually start from 12 to 24 hours after your arrival at altitude and begin to decrease in severity by about your third day at a given elevation.
>Mild AMS causes travelers to feel generally unwell. They may also suffer a loss of appetite, headache, lightheadedness, fatigue, breathlessness, rapid heartbeat, nausea, and/or difficulty sleeping. Symptoms tend to be worse at night. Mild AMS does not interfere with normal activities, and symptoms generally subside within two to four days, as the body acclimates.
>Severe AMS manifests itself in the form of serious conditions known as high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE) — the accumulation of excess fluid in the lungs or brain. The symptoms of severe AMS include a gray or pale complexion, a blue tinge to the skin (a condition known as cyanosis), chest tightness or congestion, cough, coughing up blood, difficulty walking, shortness of breath when at rest, withdrawal from social interaction, confusion, and/or decreased consciousness. Severe AMS can be fatal if it's not treated or the victim is not returned to a lower altitude.
>EFFECTS OF INCREASING ALTITUDE
>* Atmospheric pressure is 765 mmHg (millimeters of mercury, the unit of measure for pressure in gases and liquids).
>* Partial pressure of atmospheric oxygen is 160 mmHg.
>* Arterial oxygen pressure (PaO2) is 80 to 100 mmHg.
>* Arterial carbon dioxide pressure (PaCO2) is 38 to 42 mmHg.
>High altitude — 8,000 to 12,000 feet (2,438 to 3,658 meters):
>* Commercial aircraft cabin pressure is typically equivalent to the pressure at about 8,000 feet (2,438 meters).
>* Altitude sickness is common above 8,000 feet (2,438 meters).
>* The availability of oxygen drops to 90 to 65 percent of the amount at sea level.
>* Arterial PaO2 is significantly diminished.
>* Exercise performance decreases and ventilation (the exchange of air between the lungs and the atmosphere) increases due to lower arterial PaCO2.
>Very high altitude — 12,000 to 18,000 feet (3,658 to 5,486 meters):
>* Atmospheric pressure is 483 mmHg or less.
>* The availability of oxygen drops to 65 to 50 percent of the amount at sea level.
>* Arterial PaO2 falls below 60 mmHg.
>* Extreme hypoxemia (an abnormally low concentration of oxygen in the blood) may occur during exercise and sleep.
>* Severe altitude sickness occurs most commonly in this range.
>Extreme altitude — above 18,000 feet (5,486 meters):
>* The availability of atmospheric oxygen drops below 50 percent of the amount at sea level.
>* Marked hypoxemia, very low PaCO2, and alkalosis (excessive alkalinity of the body fluids) are likely to occur.
>* All physiological functions progressively deteriorate.
>* No permanent human habitation exists above 20,000 feet (6,096 meters).
>Treatment: Responding promptly to signs or symptoms of AMS is essential. It is advisable to call the nearest emergency medical service (EMS) immediately if you or someone traveling with you experience any of the following symptoms:
>* Severe breathing problems
>* Altered level of alertness
>* Coughing up blood
>If you cannot count on EMS aid, get the affected individual down to a lower altitude as quickly and as safely as possible and administer oxygen if it's available. Also, keep victims warm and, if they're conscious, be sure they stay well hydrated.
>To avoid altitude sickness, it's important to ascend slowly enough to allow time for your body to acclimate. Some people also find it beneficial to take prophylactic medication to help with the acclimatization process and/or to prevent some ill effects. If you plan to travel to a high-altitude location, visit your doctor or a travel clinic before your trip to evaluate your risk of altitude sickness and to obtain prophylactic medication that may prevent or alleviate AMS.
>Anybody can be affected by AMS. You are at higher risk if:
>* You live at or near sea level and travel to a high altitude.
>* You have had AMS before.
>* You have pre-existing medical conditions.
>* You ascend quickly to a high elevation.
>Do not travel to a high-altitude location if you have a heart, lung or blood disorder without consulting your doctor. You may need to travel with supplemental oxygen.
>Following these strategies can help to prevent and/or moderate AMS:
>* Do not ascend quickly above 8,000 feet.
>* If you travel to high altitudes, choose a slow transportation method or walk.
>* If you get there by flying, do not overexert yourself or travel still higher for the first 24 hours.
>* If you travel above 10,000 feet (3,048 meters), increase your altitude by no more than 1,000 feet (305 meters) per day.
>* After every 3,000 feet (914 meters) of elevation gained, take a rest day.
>* After daily excursions, return to a lower altitude for the night, if possible.
>* Don't go higher if you experience any AMS symptoms; wait for the symptoms to decrease first.
>* If your symptoms increase, go down!
>* Stay properly hydrated. Drink at least three to four quarts of fluids per day, and be sure to quench your thirst. Make sure to urinate regularly.
>* Light activity during the day is better than sleeping, because respiration decreases during sleep, exacerbating AMS symptoms.
>* Avoid tobacco, alcohol and depressant drugs (such as barbiturates, tranquilizers, and sleeping pills), all of which worsen AMS symptoms.
>* Eat a high-carbohydrate diet while at altitude, but do not overeat.
>Signs and symptoms: (Symptoms of a disease are subjective indications that can be detected by a patient, such as pain or fatigue, while signs are objective indications that can be detected by a doctor, such as temperature or pulse.) Even mild dehydration can result in poor judgment, weakness, headache, and lack of energy; in addition, dehydration can make those affected more susceptible to infections, hyperthermia, or decompression illness (DCI). Marked dehydration can also cause imbalances in electrolytes (salts and other minerals in blood and other body fluids).
>Individuals suffering from dehydration may also evidence a loss of elasticity in their skin, excessively dry mucous membranes (in the nose and throat, for example), and urine output that darkens in color and declines in quantity. It is of note that if you have been swimming or diving, your first urine output after immersion may be clear, even though you're dehydrated. This is due to an effect known as immersion diuresis — that is, an increased production of urine during immersion due to vasoconstriction (narrowing of the blood vessels); this results in your urine being more diluted than it would otherwise be.
>Dehydration is often suspected when someone feels unwell after having been physically active and sweating profusely in a hot, humid environment. But the condition is much more difficult to detect in cooler environments, where an individual's fluid intake still may not keep up with the loss of body fluids. Dehydration in such conditions can be insidious, in that victims may not be aware of their depleted state until an emergency arises — which can be especially dangerous if they are traveling in a remote area.
>Treatment and prevention: Travelers in hot and humid environments may need to increase their fluid intake beyond the recommended 8 cups (almost 2 liters) of water per day. When you're traveling in such climates is also not a good time to begin restricting your salt intake, because the loss of salts during prolonged exposure to heat and humidity may result in a condition called hyponatremia; it is characterized by abnormally low levels of sodium in the blood and can cause lethargy, headaches, seizures — and even death, if the brain swells due to ingestion of water but not enough salts and other electrolytes. However, this does not mean you should drink salt water! Salt water is a concentrated solution that can actually dehydrate a victim further if it is used for hydration. Studies of shipwreck survivors have clearly demonstrated that those who survived were those who refrained from drinking salt water.
>Treatment of dehydration involves replacing the lost fluids and electrolytes — orally (by mouth) in cases of mild to moderate dehydration, but intravenously in more severe cases. Administering frequent, small amounts of water is the best approach.
>Lightning: The Earth receives an estimated 100 lightning strikes per second. So it should be no surprise that sometimes lightning strikes humans. In 2014, 26 people died from lightning strikes in the U.S. Worldwide estimates of lightning fatalities range from 6,000 to 24,000 per year. An individual's lifetime odds of being killed by lightning are 1 in about 165,000. The U.S. Centers for Disease Control and Prevention (CDC) recommends the following strategies to avoid being struck by lightning:
>* Check the weather forecast before an outdoor excursion.
>* If you hear thunder, seek shelter if possible — in an enclosed building or a hard-topped vehicle with the windows rolled up. Do not stay in an open structure or vehicle, such as a porch or golf cart.
>* If you can't get to shelter and you're in an open area, crouch down in a ball-like position, with minimal contact with the ground. Do not lie down.
>* If possible, avoid ridgelines, mountain summits, and isolated trees or other tall items like power poles. If you are in the woods, stay near shorter trees.
>* Stay away from water — swimming pools, ponds, rivers, and even puddles.
>* Avoid tall structures.
>* Avoid contact with anything metal. (And if you are in a concrete structure, avoid leaning against the walls, as lightning can travel through the metal reinforcement in concrete.)
>* Be sure you are not wearing or carrying anything metal.
>* If you are in a group, separate from each other.
>If you or someone you are with does get struck by lightning, call for emergency medical assistance immediately. Then take these steps:
>* Minimize the risk of further strikes, moving the victim to a safer location if necessary.
>* Check to see if the victim is breathing and has a heartbeat. If not, start chest compressions immediately. Initiate rescue breathing if anyone in your group has CPR training. Learn more about essential skills and CPR.
>* Continue chest compressions (and CPR) until medical personnel arrive.
>* Assess the victim for other injuries, such as burns or blunt trauma, and administer first aid as appropriate and possible.
>* If there is risk of hypothermia, place an insulating layer between the victim and the ground.
>Sunburn: The depletion of the Earth's ozone layer has made sunburn an increasingly common hazard of outdoor activities. The U.S. Skin Cancer Foundation has determined that 42 percent of Americans get at least one sunburn a year. And your risk of melanoma, the most deadly form of skin cancer, doubles after just five or more blistering sunburns. Prevention is much more important than treatment. To avoid getting sunburned, the Skin Cancer Foundation suggests these steps:
>* Stay in the shade or indoors, especially between 10:00 a.m. and 4:00 p.m. and especially in tropical and polar latitudes and at high altitudes.
>* Use a sunscreen with an SPF factor of at least 15. Apply it liberally to all exposed skin 30 minutes before going outdoors, then reapply it every two hours.
>* Use sun-protective clothing, including a broad-brimmed hat and sunglasses that block UV radiation.
>* Remember, if you're near water, sand or snow, that the sun reflects off such surfaces, increasing the intensity of the UV rays.
>* Remember, too, that you can get a sunburn on a cloudy day; in fact, some cloud formations can magnify the effect of the sun's UV rays.
>* Do not use tanning booths.
>If you do get too much sun, here's what to do:
>* Take a cool shower or bath.
>* Apply moisturizing lotion.
>* Stay well hydrated.
>* If you get a painful burn, a pain reliever such as ibuprofen (Advil) can help.
>* If a blistering sunburn covers more than 20 percent of your body, you should seek medical attention.
>In addition, it's a good idea to check your skin for unusual moles or other signs of potential skin cancer at least once a month.
>Poison ivy, oak and sumac: Poison ivy, oak and sumac are the most common contact-poisonous plants in the United States, but there are others within U.S. borders and many more elsewhere around the world. Learning to recognize the leaves of noxious plants is the best way to avoid the misery of the highly itchy rashes they can cause. Learn more about poisonous plants from the CDC . And before you engage in wilderness activities in other parts of the world, research what plants you should watch for there. Remember, too, that it is possible to be exposed to urushiol, the natural chemical that causes the allergic rash, through direct contact with the plant, through indirect contact with a surface that has touched the plant, or by inhaling particles from burning plants that contain urushiol.
>The CDC recommends the following preventive steps if you may come into contact with such plants:
>* Cover up — wear long sleeves, long pants, and gloves.
>* Consider the use of a barrier lotion containing bentoquatum, for example; however, such lotions must be washed off and reapplied twice a day.
>* Clean any gear that may have come in contact with such plants with rubbing alcohol (isopropanol or isopropyl alcohol) or soap and water; urushiol can remain potent on the surface of objects for up to five years.
>* Do not ever burn plants that may contain urushiol or similar substances.
>But if, despite your best efforts, you do come in contact with poisonous plants, the CDC recommends these steps:
>* Immediately wash well with rubbing alcohol, a specialized plant wash, or a degreasing soap (such as dishwashing liquid) and lots of water. Then rinse well.
>* Scrub under your nails with a brush.
>* If you have a blistering rash, apply wet compresses, calamine lotion or hydrocortisone cream to mitigate the itching. An oatmeal bath or oral antihistamines (such as Benadryl) may also relieve itching.
>* In case of a severe allergic reaction or severe itching or blistering, seek medical attention.