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= Drowning = Drowning is a form of suffocation resulting from immersion of the mouth and nose in liquid, usually water.[7][9] Prolonged submersion leads to low oxygen levels and excess carbon dioxide in the blood, triggering a neurological state of breathing emergency, which results in physical distress and occasional contractions of the vocal folds.[11] Significant quantities of water usually enter the lungs later in the process.[4]

Drowning can be fatal, or cause ongoing health problems, though these outcomes are not universal.[9] Incidents of fatal drowning typically occur in solitude, or in situations where others are unaware of the victim’s situation or cannot to provide assistance.[1] After rescue, victims may still experience difficulty breathing, vomiting, confusion, or unconsciousness.[2][3] These symptoms may not manifest until several hours after rescue.[3] Further complications can result from low body temperature, aspiration of vomit, or acute respiratory distress syndrome.[4][10] People are hospitalized after nonfatal drowning at four times the rate of fatal incidents.[3]

Factors that increase the risk of drowning include lack of attention to children, alcohol, use, epilepsy, and lack of proper swimming skills.[6] Drowning occurs more frequently during warm weather, as it prompts people to gravitate towards large bodies of water.[4][6] Drowning occurs in natural bodies of water, as well as man-made settings, such as pools and hot tubs.[3][7] Children can drown in small bodies of water, such as toilets and buckets.[3] Poor outcomes occur in about 7.5% of children who survive drowning.[7]

Steps to prevent drowning include: teaching children and adults how to swim, and how to recognize unsafe water conditions; well-documented safe boating practices; limiting or removing access to water, such as with fencing of swimming pools; and exercising appropriate supervision.[6][5]

Causes
A major cause of drowning is the inability to swim. Other contributing factors include the state of the water, distance from solid footing, physical impairment, or prior loss of consciousness. Anxiety inspired by a fear of drowning can cause exhaustion, thus increasing the chances of drowning.[15]

Approximately 90% of drowning takes place in freshwater – rivers, lakes, and sometimes swimming pools; the remaining 10% of cases take place in seawater.[12] Children can drown in water as shallow as one inch (three centimeters) deep.[15]

Complications can occur up to 72 hours after the initial incident, leading to serious injury or death.[16] Inhaled fluid can act as an irritant inside the lungs. Even small quantities can cause the extrusion of liquid into the lungs (pulmonary edema) over following hours; this impairs the body’s ability to exchange the air, and can lead to a person "drowning in their own body fluid." Vomit, as well as certain poisonous vapors or gases (such as those employed in chemical warfare) can have a similar effect.

Risk factors
Many factors, both behavioral and physical, are related to drowning:[17][18]


 * Inability to swim can lead to drowning. Participation in formal swimming lessons can reduce this risk. The optimal age to start the lessons is in childhood, between one and four-years-old.[21]
 * Imbibing alcohol increases the risk of drowning in both developed and developing nations. Alcohol is involved in approximately 50% of fatal drownings, and 35% of non-fatal drownings.[20]
 * Exhaustion reduces swimming performance. Inaccurate appraisal of one’s physical abilities can lead to “swimming out too far,” leading to exhaustion before one can return to solid footing. Exhaustion can be exacerbated by movements made in fear, or anticipation, of drowning.[15]
 * Ineffective supervision. Drowning can occur anywhere there is water, even in the presence of lifeguards.
 * Unrestricted access to water can be hazardous, especially to young children. Barriers, such as fences or gates, can curtail this danger.
 * Drowning is the most common cause of death for persons with seizure disorders. Most often, this occurs in bathtubs. Epileptics have an increased risk of dying due to drowning. This risk is elevated further in low- and middle-income countries.[19]

Demographics
Risk of drowning varies depending on location and age. Drowning rates are highest among children under five, and persons between fifteen and twenty-four-years-old.[17] Children between one and four drown most often in swimming pools. More than half of persons fifteen and older drown in natural water environments.[22] 80% of drowning victims are male. The rate of fatal drownings among African American children aged five to fourteen is nearly triple that of Caucasian children of the same age, and 5.5 times higher in swimming pools.[23] Between 1999 and 2010, the rate of fatal drowning for African Americans above twenty-nine was significantly higher than that of Caucasians.[23]

Freediving
Additional risk factors can accompany freediving activities:


 * Shallow water blackout occurs in conjunction with hyperventilation before swimming or diving. The body triggers the urge to breathe based on rising levels of carbon dioxide (CO2 ) in the bloodstream.[25] Hyperventilation reduces the CO2 content of the blood, but leaves the diver susceptible to sudden loss of consciousness due to hypoxia. There is no sensation that warns a diver of an impending blackout.


 * Ascent blackout can result from hypoxia during ascent. The pressure at the bottom of a deep free dive is adequate to support consciousness, but drops below the blackout threshold as the water pressure decreases during ascent. It usually strikes upon arriving near the surface, as the pressure approaches normal atmosphere levels.[24] The resulting blackout can leave diver’s vulnerable to drowning.

Pathophysiology
Drowning is described as occurring in four stages:[27]


 * Breath is held voluntarily, until the urge to breathe due to hypercapnia grows overwhelming
 * Fluid is swallowed and/or aspirated into the airways.
 * Cerebral anoxia halts breathing and aspiration.
 * Cerebral injury resulting from anoxia becomes irreversible.

Generally, in the early stages of drowning, a person holds their breath to prevent water from entering their lungs.[7] When this is no longer possible, a small quantity of water entering the trachea causes a muscular spasm that seals the airway and prevents further passage of water.[7] If the process is not interrupted, loss of consciousness due to hypoxia is quickly followed by cardiac arrest.

(No changes made between “Oxygen deprivation” subheading and “Prevention” heading.)

Prevention
It is estimated that over 85% of drownings are preventable. There are numerous ways in which this can be accomplished.[49][32]


 * Swimming lessons: The ability to swim is one of the best defenses against drowning. It is recommended that children learn to swim in a safe, supervised environment between the ages of one and four-years-old. Factors such as the state of the water or unforeseen weather can lead to drowning, even for people who know how to swim. Thus, it is recommended to choose swimming places that are safe, and kept under surveillance.
 * Follow the rules: Most swimming spots include signage indicating if swimming is possible, as well as safety directions created by authorities – lifeguards, coastguards, etc. Reading and adhering to such instructions minimizes the risk of drowning.
 * Avoid dangerous waters: Certain conditions can make swimming spots unsafe. These include turbulent waters, large waves, dangerous animals, or low temperature. Dragging currents, which are turbulent waters that can drag debris or people, should be avoided. In the event of being caught in such a current, it should be swam away from. It is possible to move out gradually, in a diagonal direction, until arrival at shore.
 * Surveillance: Keeping an eye on swimmers mitigates the risk of silent drowning occurring. Many pools and bathing areas employ lifeguards or a pool safety camera system to this end. Some have computer-aided drowning detection. However, evidence suggests that alarms in pools are poor for any utility.[51] Lifeguards may be unaware of a drowning due to "the intrusion of non-lifeguard duties upon lifeguards' primary task: preventive lifeguarding" and because of “the distraction from surveillance duties.”[50] To counteract this, the World Health Organization (WHO) recommends analyzing when the most crowded hours in the swimming zones are, and to increase the number of lifeguards during such periods. Bystanders can alert lifeguards of potential drownings. Surveillance is especially important for children, even if they know how to swim.
 * Additional education: The WHO recommends the general public should train themselves in first-aid procedure for the drowned and cardiopulmonary resuscitation (CPR), as well as behave safely when in water. Furthermore, they suggest those who cannot swim should keep away from deep waters.
 * Alcohol or drugs: Alcohol and drugs increase the probability of drowning. The danger is greater in bars located near water, or at celebrations on boats where alcohol is consumed. Finland sees several drownings occur annually during Midsummer weekend, when many Finnish people spend time near lakes and beaches while intoxicated.[55][56][57]
 * Pool fencing: Fencing or enclosure around swimming pools, both private and public, prevents unauthorized or unsupervised access to the water.[52] The “Raffarin law,” applied in France in 2003, mandated the fencing of pools.[53]
 * Pool drains: Swimming pools often use drainage systems to cycle their water. Uncovered drains can cause injury to swimmers by trapping hair or other body parts. This can lead to immobilization and drowning. It is recommended for pools to have many small drainage holes, rather than a single large one, to prevent powerful suction from causing harm.
 * Depth awareness: People should be aware of the water’s depth before entering. Attempting to dive into shallow water can cause serious injury. Up to 21% of shallow-water diving accidents result in spinal injury, and sometimes death. Between 1.2-22% of all spinal injuries are from diving accidents. If not fatal, the injury can result in permanent paralysis .[59]
 * Lifejacket: Children who cannot swim, as well as other people at risk of drowning, can be protected from drowning by being fitted with a personal flotation device —also known as a lifejacket—while in or near water. Some floatation devices, such as inflatable inner tubes, water wings, or foam tubes serve a similar purpose, although they are usually considered toys.[58] The lifebuoy is a buoyant ring-shaped floatation device meant to be thrown to a person in water, allowing them to latch onto it and avoid drowning. Some professional variants are used by lifeguards during rescues.
 * Navigating safely: Navigation accidents made while boating can lead to drowning. Being informed of the state of the sea, and equipping the boat with regulatory instruments to keep people afloat, curtail the risk of drowning. Regulatory instruments may include the aforementioned lifejackets and lifebuoys.
 * Caution with certain conditions: Some conditions require caution when near water. Epilepsy and other seizure disorders increase the risk of drowning due to involuntary convulsions. It is recommended that people with these conditions take showers rather than baths, and are taught about the dangers of drowning.[54]
 * The "buddy system": Swimming with another person helps to mitigate the risk of drowning. In the event of drowning, they can assist in extracting the victim from the water, or alerting a lifeguard or other qualified professional.

(No changes made between “Management” heading and “References” heading.)