Apollutant ornovel entity[1] is a substance or energy introduced into the environment that has undesired effect, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds likeoil) oranthropogenic in origin (i.e. manufactured materials orbyproducts). Pollutants result inenvironmental pollution or become of public health concern when they reach aconcentration high enough to have significant negative impacts.
A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with resources used by humans, human health or wellbeing, or property values. Some pollutants arebiodegradable and therefore will not persist in theenvironment in a long term. However, the degradation products of some pollutants are themselves pollutants such asDDE andDDD produced from the degradation ofDDT.
Pollution has widespread negative impact on the environment.[1] When analyzed from aplanetary boundaries perspective, human society has released novel entities that well exceed safe levels.[1]
Pollutants can be categorized in a variety of different ways. For example, it is sometimes useful to distinguish betweenstock pollutants andfund pollutants. Another way is to group them together according to more specific properties, such as organic, particulate, pharmaceutical, et cetera. The environment has some capacity to absorb many discharges without measurable harm, and this is called “assimilative capacity (or absorptive capacity); a pollutant actually causes pollution when the assimilative capacity is exceeded.[2]
Pollutants, towards which the environment has lowabsorptive capacity are calledstock pollutants.[3] Examples includepersistent organic pollutants likePCBs, non-biodegradableplastics andheavy metals. Stock pollutants accumulate in the environment over time. The damage they cause increases as more pollutant is emitted, and persists as the pollutant accumulates. Stock pollutants can create a burden for thefuture generations, bypassing on the damage that persists well after the benefits received from incurring that damage, have been forgotten.[3] Scientists have officially deemed that the planetary boundaries safe chemical pollutant levels (novel entities) have been surpassed.[1]
In contrast to stock pollutants, for which the environment has low absorptive capacity, fund pollutants are those for which the environment has a moderate absorptive capacity. Fund pollutants do not cause damage to the environment unless the emission rate exceeds the receiving environment's absorptive capacity (e.g. carbon dioxide, which is absorbed by plants and oceans).[3] Fund pollutants are not destroyed, but rather converted into less harmful substances, or diluted/dispersed to non-harmful concentrations.[3]
Many pollutants are within the following notable groups:
Light pollution is the impact that anthropogenic light has on the visibility of the night sky. It also encompassesecological light pollution which describes the effect ofartificial light on individualorganisms and on the structure ofecosystems as a whole.[5]
Pollutants can also be defined by their zones of influence, both horizontally and vertically.[3]
The horizontal zone refers to the area that is damaged by a pollutant. Local pollutants cause damage near the emission source. Regional pollutants cause damage further from the emission source.[3]
The vertical zone refers to whether the damage is ground-level or atmospheric. Surface pollutants cause damage by accumulating near the Earth's surface. Global pollutants cause damage by concentrating on the [atmosphere].
Measures of pollutant concentration are used to determinerisk assessment in public health.
Industry is continuallysynthesizing new chemicals, the regulation of which requires evaluation of the potential danger forhumanhealth and theenvironment. Risk assessment is nowadays considered essential for making these decisions on a scientifically sound basis.
Measures or defined limits include:
Pollutants can cross international borders and therefore international regulations are needed for their control. TheStockholm Convention on Persistent Organic Pollutants, which entered into force in 2004, is an international legally binding agreement for the control of persistent organic pollutants.Pollutant Release and Transfer Registers (PRTR) are systems to collect and disseminate information on environmental releases and transfers of toxic chemicals from industrial and other facilities.
TheEuropean Pollutant Emission Register is a type of PRTR providing access to information on the annual emissions of industrial facilities in the Member States of theEuropean Union, as well as Norway.[7]
Clean Air Act standards. Under theClean Air Act, theNational Ambient Air Quality Standards (NAAQS) are developed by theEnvironmental Protection Agency (EPA) for six common air pollutants, also called "criteria pollutants":particulates;smog andground-level ozone;carbon monoxide;sulfur oxides;nitrogen oxides; andlead.[8] TheNational Emissions Standards for Hazardous Air Pollutants are additional emission standards that are set by EPA for toxic air pollutants.[9]
Clean Water Act standards. Under theClean Water Act, EPA promulgated national standards for municipalsewage treatment plants, also calledpublicly owned treatment works, in theSecondary Treatment Regulation.[10] National standards for industrial dischargers are calledEffluent guidelines (for existing sources) andNew Source Performance Standards, and currently cover over 50 industrial categories.[11] In addition, the Act requiresstates to publishwater quality standards for individual water bodies to provide additional protection where the national standards are insufficient.[12]
RCRA standards. TheResource Conservation and Recovery Act (RCRA) regulates the management, transport and disposal ofmunicipal solid waste,hazardous waste andunderground storage tanks.[13]
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