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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.
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.
Hazards have the potential to cause adverse effects only if they come into contact with populations that may be harmed. For this reason, hazard identification includes the development of a conceptual model of exposure. [8] Conceptual models communicate the pathway connecting sources of a given hazard to the potentially exposed population(s).
Noise pollution may have caused the death of certain species of whales that beached themselves after being exposed to the loud sound of military sonar. [71] (see also Marine mammals and sonar) Up until recently, most research on noise impacts has been focused on marine mammals, and to a lesser degree, fish.
Thermal pollution is the rise or drop in the temperature of a natural body of water caused by human influence. Thermal pollution, unlike chemical pollution, results in a change in the physical properties of water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. [46]
Sources of water pollution are either point sources or non-point sources. [156] 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. [157] Pollution is the result of the cumulative effect over time.
For example, water pollution with toxic chemicals is an anthropogenic hazard as well as an environmental hazard. One of the classification methods is by specifying the origin of the hazard. One key concept in identifying a hazard is the presence of stored energy that, when released, can cause damage.
Air pollution — Atmospheric particulate matter • Biological effects of UV exposure • CFC • Environmental impact of the coal industry • Environmental impact of hydraulic fracturing • Indoor air quality • Ozone depletion • Smog • Tropospheric ozone • Volatile organic compound • Ultrafine particles Light pollution Noise pollution