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Air pollution can occur naturally or be caused by human activities. [4] Air pollution causes around 7 or 8 million deaths each year. [5] [6] It is a significant risk factor for a number of pollution-related diseases, including heart disease, stroke, chronic obstructive pulmonary disease (COPD), asthma and lung cancer.
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.
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.
Air pollution is caused predominantly by burning fossil fuels, cars, and much more. [4] Natural sources of air pollution include forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity. These natural sources of pollution often soon disperse and thin settling near their locale.
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.
Smog, or smoke fog, is a type of intense air pollution.The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog [1] to refer to smoky fog due to its opacity, and odor. [2]
[4] [5] Air pollution in the UK is a major cause of diseases such as asthma, lung disease, stroke, cancer, and heart disease, and it costs the health service, society, and businesses over £20 billion each year. [6] Outdoor pollution alone is estimated to cause 40,000 early deaths each year, which is about 8.3% of deaths. [7] [8]
This is in part because pollution causes so many diseases that it is often difficult to draw a straight line between cause and effect. There are many types of pollution-related diseases, including those caused by air pollution, contaminated soil, water pollution and lacking water, sanitation and hygiene (WASH). Air pollution can be reduced.