Diseases, Conditions, Syndromes

Mayo Clinic minute: Heat exhaustion and heatstroke

As the temperature rises in the summer, so does the risk of heat-related illnesses, like heat exhaustion and heatstroke. Over the past 30 years, extreme heat has claimed more lives in America than any other weather-related ...


Pollution's deadly toll continues unabated

Pollution continues to kill approximately 9 million people around the world on an annual basis, according to a follow-up study to a landmark 2018 report by The Lancet Commission on Pollution and Health, a global research ...


Mayo Clinic minute: What drowning doesn't look like

Wide reports of a lifeguard shortage around the nation mean many public swimming pools and beaches may be closed for the summer. Without trained lifeguards on duty, water safety becomes an issue especially for children.

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Water is a ubiquitous chemical substance, composed of hydrogen and oxygen, that is essential for the survival of many known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.

Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.

Clean, fresh drinking water is essential to human and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.

This text uses material from Wikipedia, licensed under CC BY-SA