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Air pollution can cause diseases, allergies, and even death; it can also cause harm to animals and crops and damage the natural environment (for example, climate change, ozone depletion or habitat degradation) or built environment (for example, acid rain). [3] Air pollution can occur naturally or be caused by human activities. [4]
Various definitions of pollution exist, which may or may not recognize certain types, such as noise pollution or greenhouse gases.The United States Environmental Protection Administration defines pollution as "Any substances in water, soil, or air that degrade the natural quality of the environment, offend the senses of sight, taste, or smell, or cause a health hazard.
Delhi is the most polluted [56] city in the world and according to one estimate, air pollution causes the death of about 10,500 people in Delhi every year. [ 57 ] [ 58 ] [ 59 ] During 2013–14, peak levels of fine particulate matter (PM) in Delhi increased by about 44%, primarily due to high vehicular and industrial emissions, construction ...
NO x gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines. [1] [2] [3] In areas of high motor vehicle traffic, such as in large cities, the nitrogen oxides emitted can be a significant source of air pollution.
Looking down from the Hollywood Hills, with Griffith Observatory on the hill in the foreground, air pollution is visible in downtown Los Angeles on a late afternoon.. Air pollution is the introduction of chemicals, particulate matter, or biological materials into the atmosphere that cause harm or discomfort to humans or other living organisms, or damage ecosystems.
Sources of water pollution are either point sources or non-point sources. [155] Point sources have one identifiable cause, such as a storm drain, a wastewater treatment plant, or an oil spill. Non-point sources are more diffuse. An example is agricultural runoff. [156] Pollution is the result of the cumulative effect over time.
In European countries, air quality at or above 10 micrograms per cubic meter of air (μg/m 3) for PM 2.5 increases the all-causes daily mortality rate by 0.2-0.6% and the cardiopulmonary mortality rate by 6-13%. [35] Worldwide, PM 10 concentrations of 70 μg/m 3 and PM 2.5 concentrations of 35 μg/m 3 have been shown to increase long-term ...
On regional and global scale, air pollution can affect the water cycle, in a manner similar to some natural processes. One example is the impact of Sahara dust on hurricane formation: air laden with sand and mineral particles moves over the Atlantic Ocean, where they block some of the sunlight from reaching the water surface, slightly cooling ...