This glossary contains terms you may run across on this site or in some other EHS context.
Degradation: The process by which a chemical is reduced to a less complex form.
Delegated State: A state (or other governmental entity such as a tribal government) that has received authority to administer an environmental regulatory program in lieu of a federal counterpart. As used in connection with NPDES, UIC, and PWS programs, the term does not connote any transfer of federal authority to a state.
Delist: Use of the petition process to have a particular waste excluded from regulation at a particular generating facility. For more information, see the Delisting Petitions topic page.
Designated Pollutant: An air pollutant that is neither a criteria nor hazardous pollutant, as described in the Clean Air Act, but for which New Source Performance Standards exist. The Clean Air Act does require states to control these pollutants, which include acid mist, total reduced sulfur, and fluorides.
Dewater: 1: Remove or separate a portion of the water in a sludge or slurry to dry the sludge so it can be handled and disposed. 2: Remove or drain the water from a tank or trench.
Discharge: Flow of surface water in a stream or canal or the outflow of groundwater from a flowing artesian well, ditch, or spring. Can also apply to discharge of liquid effluent from a facility or to chemical emissions into the air through designated venting mechanisms.
Disposal: 1: Final placement or destruction of toxic, radioactive, or other wastes. 2: Surplus or banned pesticides or other chemicals, polluted soils, and drums containing hazardous materials from removal actions or accidental releases. Disposal may be accomplished through use of approved secure landfills, surface impoundments, land farming, deep well injection, ocean dumping, or incineration.
Dredging: Removal of mud from the bottom of water bodies using a scooping machine. This disturbs the ecosystem and causes silting that can kill aquatic life. Dredging of contaminated muds can expose aquatic life to heavy metals and other toxics. Dredging activities may be subject to regulation under section 404 of the Clean Water Act.
Drinking Water Standards: Water quality standards measured in terms of suspended solids, unpleasant taste, and microbes harmful to human health. Drinking water standards are included in state water quality rules. For more information, see the Drinking Water topic page.
Drip Pad: An engineered structure consisting of a curbed, free-draining base, constructed of non-earthen materials and designed to convey preservation kick-back or drippage from treated wood, precipitation, and surface water run-on to an associated collection system at wood preserving plants. Drip pads are subject to federal treatment, storage, and disposal facility (TSDF) rules (40 CFR 264.570 to 575).
EC50: The median effective concentration of a toxic substance. Generally, this is a statistical estimate of the concentration that has a specified adverse effect on 50 percent of the test organisms under specified test conditions, based on the results of an acute bioassay.
Ecology: The relationship of living things to one another and their environment, or the study of such relationships.
Ecosystem: The interacting system of a biological community and its nonliving environmental surroundings.
Effluent: Wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters.
Effluent Limitation: Restrictions established by a state or EPA on quantities, rates, and concentrations of wastewater discharges. For more information, see the Effluent Limitations topic page.
Elementary Neutralization Unit: 1: Used for neutralizing wastes that are hazardous only because they exhibit the corrosivity characteristic defined in 40 CFR 261.22, or they are listed in subpart D of 40 CFR 261, only for this reason. 2: Meets the definition of tank, tank system, container, transport vehicle, or vessel in 40 CFR 260.10.
Emission: Pollution discharged into the atmosphere from smokestacks, other vents, and surface areas of commercial or industrial facilities; from residential chimneys; and from motor vehicle, locomotive, or aircraft exhausts.
Emission Standard: The maximum amount of air polluting discharge legally allowed from a single source, mobile or stationary.
Emissions Trading: EPA policy that allows a plant complex with several facilities to decrease pollution from some facilities while increasing it from others, as long as total results are equal to or better than previous limits. Facilities where this is done are treated as if they exist in a bubble in which total emissions are averaged out. Complexes that reduce emissions substantially may “bank” their “credits” or sell them to other industries. Emissions trading may be required to receive a permit to operate a new source in a nonattainment area.
Encapsulate: Total enclosure of a waste in another material that isolates the waste material from outside conditions.
Encapsulation: The treatment of asbestos-containing material with a liquid that covers the surface with a protective coating or embeds fibers in an adhesive matrix to prevent their release into the air.
Endangered Species: Animals, birds, fish, plants, or other living organisms threatened with extinction by man-made or natural changes in their environment. Requirements for declaring a species endangered are contained in the Endangered Species Act.
Energy Recovery: Obtaining energy from waste through a variety of processes (e.g., combustion).
Enforcement: EPA, state, or local legal actions to obtain compliance with environmental laws, rules, regulations, or agreements and/or obtain penalties or criminal sanctions for violations. Enforcement procedures may vary, depending on the specific requirements for different environmental laws and related regulatory requirements. For more information, see the Enforcement topic page.
Environmental Assessment: A written environmental analysis that is prepared pursuant to the National Environmental Policy Act to determine whether a federal action would significantly affect the environment and would require preparation of a more detailed environmental impact statement. Many states also require applicants of proposed grants to complete an environmental assessment.
Environmental Audit: 1: An independent assessment of the current status of a party’s compliance with applicable environmental requirements. 2: An independent evaluation of a party’s environmental compliance policies, practices, and controls. For more information, see the Audits topic page.
Environmental Equity/Justice: Equal protection from environmental hazards for individual groups, or communities regardless of race, ethnicity, or economic status. This applies to the development, implementation, and enforcement of environmental laws, regulations, and policies, and implies that no population of people should be forced to shoulder a disproportionate share of negative environmental impacts.
Environmental Impact Statement: A document required of federal agencies by the National Environmental Policy Act for major projects or legislative proposals significantly affecting the environment. A tool for decision making, it describes the positive and negative effects of the undertaking and lists alternative actions. Many states also require applicants of proposed projects to complete an environmental impact statement. For more information, see the Environmental Impact Statement topic page.
Environmental Response Team: EPA experts who can provide around-the-clock technical assistance to EPA regional offices and states during all types of emergencies involving hazardous waste sites and spills of hazardous substances.
EPA: The U.S. Environmental Protection Agency, established in 1970 by Presidential Executive Order, bringing together parts of various government agencies involved with the control of pollution. For more information, see the Environmental Protection Agency
Epilimnion: The surface water of a lake that is warmer and more oxygenated than the lower stratified layers.
Episode (Pollution): An air pollution incident in a given area caused by concentration of atmospheric pollution reacting with meteorological conditions that may result in a significant increase in illnesses and deaths. Although most commonly used for air pollution, the term also is used with other kinds of environmental events such as a massive water pollution situation.
Equivalent Method: Any method of sampling and analysis for air pollution that has been demonstrated to the EPA regional administrator’s (or authorized state administrator) satisfaction to be, under specific conditions, an acceptable alternative to the normally used reference methods.
Erosion: The wearing away of land surface by wind or water. Erosion occurs naturally from weather or runoff but may be intensified by land-clearing practices related to farming, residential or industrial development, road building, or timber clearing.
Estuary: Regions of interaction between rivers and near-shore ocean waters, where tidal action and river flow mix fresh and salt water. Such areas include bays, mouths of rivers, salt marshes, and lagoons. These brackish water ecosystems shelter and feed marine life, birds, and wildlife (see: Wetlands).
Eutrophication: The process by which a body of water becomes, either naturally or by pollution, rich in dissolved nutrients and sediments.
Evaporation Ponds: Areas where sewage sludge is dumped and allowed to dry out.
Exposure: The amount of radiation or pollutant present in an environment that represents a potential health threat to the living organisms in the environment.
Extremely Hazardous Substances: Any of the chemicals identified by EPA based on toxicity, and listed under SARA Title III. The list is periodically revised and published in the Federal Register. EPA has identified nearly 300 extremely hazardous substances.
Enviro Glossary Terms A
Enviro Glossary Terms B and C
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