Environmental health is concerned with how both the natural and built environment affect human health by looking at the impact of physical, chemical and biological factors external to humans. Those working in Environmental health fields are concerned with preventing diseases or other illnesses by assessing and controlling environmental factors that pose a threat to human health whether it involves air quality, natural disasters, radiation, water quality, UV exposure, indoor air pollutants, climate change, healthy communities and work environments, or the effects of toxic substances. Environmental health can also refer to ecosystem status or function. Chemicals, diseases, and invasive species threaten to alter wildlife and plant populations, which in turn may impact ecosystem function. Maintaining health, whether ecosystem or human arguably presents one of the greatest challenges of the day, in general maintaining optimal ecosystem function is essential for continued survival of all species including humans.
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PollutionLast Updated on 2014-11-09 17:40:04Pollution is environmental contamination that results in harm or death to living organisms. Most pollution is in the form of chemical additions to air, water or soil; however, in modern times starting in the mid-twentieth century noise and light have been considered as pollution sources. Most pollution is man-made, with natural fluctuations in atmospheric composition, surface water bodies and soil considered temporal gyrations in the Earth's natural history. The chief driver of pollution is the massive growth in human population, which induces the proximate causes of intensive agriculture and extraordinary industrial output. The United Nations and the Blacksmith Institute are two prominent organisations that tabulate locales of the greatest pollution intensity; while their listings do not correspond precisely, the overlap countries that both entities agree are the worst polluted... More »
Gut reaction: environmental effects on the human microbiotaLast Updated on 2014-10-13 22:34:38This article, written by Melissa Lee Phillips, appeared first in Environmental Health Perspectives—the peer-reviewed, open access journal of the National Institute of Environmental Health Sciences.
The article is a verbatim version of the original and is not available for edits or additions by Encyclopedia of Earth editors or authors. Companion articles on the same topic that are editable may exist within the Encyclopedia of Earth.
Living with each of us—on our skin, in our mucosa, and in our gastrointestinal (GI) tract—are microorganisms whose numbers dwarf the number of our own cells and genes. Although some of these microbes are pathogens, most are harmless or even beneficial. The body’s assortment of microorganisms, collectively called the microbiota, is similar to an organ in that it performs functions essential for our survival. Some microbes produce... More »
Air quality in megacitiesLast Updated on 2014-09-18 16:40:27
Ambient air pollution in an increasingly urbanized world directly threatens the health of a large fraction of the world’s population. There is growing recognition that air-borne emissions from major urban and industrial areas influence both air quality and climate change on scales ranging from regional up to continental and global. Deteriorating urban air quality affects the viability of important natural and agricultural ecosystems in regions surrounding highly urbanized areas, and significantly influences regional atmospheric chemistry and global climate change. This challenge is particularly acute in the developing world where the rapid growth of megacities (cities having population equal to or more than 10 million) is producing atmospheric pollution of unprecedented severity and extent. For example, the deterioration of air quality is a problem that is directly experienced... More »
FluorineLast Updated on 2014-09-13 19:14:38Fluorine is a highly reactive chemical element with atomic symbol F. Having the atomic number nine, fluorine is the lightest halogen. Fluorine is a yellow-green gas which does not occur as a free, unreacted element in the natural environment. Under conditions of standard temperature and pressure, elemental fluorine forms a diatomic molecule with chemical formula F2. Chemically, fluorine is one of the strongest known oxidizing agents, and even more reactive and hazardous than chlorine. Its very high electron affinity causes fluorine to react directly with almost all other elements except for several of the Noble gases.
Previous Element: Oxygen
Next Element: Neon
Phase at Room Temp.
Density... More »
CellsLast Updated on 2014-06-30 14:15:10
Cells are the smallest component of the body that can perform all of the basic life functions. Each cell performs specialized functions and plays a role in the maintenance of homeostasis. While each cell is an independent entity, it is highly affected by damage to neighboring cells. These various cell types combine to form tissues, which are basically collections of specialized cells that perform a relatively limited number of functions specific to that type of tissue. The human body is made up of several trillion cells; these cells are of various types, which can differ greatly in size, appearance and function.
While there are approximately 200 types of cells, they all have similar features: cell membrane, cytoplasm, organelles, and nucleus. The only exception is that the mature red blood cell does not contain a nucleus. In general, toxins can injure any of the components of... More »
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