Definition 1: Methanes substituted with three halogen atoms, which may be the same or different. [NLM Medical Subject Headiangs (MeSH)]

Definition 2: Family of organic compounds, named as derivatives of methane, wherein three of the four hydrogen atoms in methane are each substituted by a halogen atom in the molecular structure.[Adapted from 40 CFR 141.2 (CFR 2018)]

Definition 1: Organic compounds made up of atoms of carbon, chlorine, and fluorine. An example is CFC-12, used as a refrigerant in refrigerators and air conditioners and as a foam blowing agent. Gaseous CFCs can deplete the ozone layer when they slowly rise into the stratosphere, are broken down by strong ultraviolet radiation, release chlorine atoms, and then react with ozone molecules. [Greenhouse Emissions Glossary]

Definition 2: Manufactured substances used as coolants and computer-chip cleaners. When these products break down they destroy stratospheric ozone, creating the Antarctic Ozone Hole in the Southern Hemisphere spring (Northern Hemisphere autumn). While no longer in use, their long lifetime will lead to a very slow removal from the atmosphere. [NOAA National Weather Service Glossary]

Definition 3: A family of compounds of chlorine, fluorine, and carbon, entirely of industrial origin. CFCs include refrigerants, propellants for spray cans (this usage is banned in the U.S., although some other countries permit it) and for blowing plastic-foam insulation, styrofoam packaging, and solvents for cleaning electronic circuit boards. The compounds' lifetimes vary over a wide range, exceeding 100 years in some cases. CFCs' ability to destroy stratospheric ozone through catalytic cycles is contributing to the depletion of ozone worldwide. Because CFCs are such stable molecules, they do not react easily with other chemicals in the lower atmosphere. One of the few forces that can break up CFC molecules is ultraviolet radiation, however the ozone layer protects the CFCs from ultraviolet radiation in the lower atmosphere. CFC molecules are then able to migrate intact into the stratosphere, where the molecules are bombarded by ultraviolet rays, causing the CFCs to break up and release their chlorine atoms. The released chlorine atoms participate in ozone destruction, with a single atom of chlorine able to destroy ozone molecules over and over again. International attention to CFCs resulted in a meeting of diplomats from around the world in Montreal in 1987. They forged a treaty that called for drastic reductions in the production of CFCs. In 1990, diplomats met in London and voted to significantly strengthen the Montreal Protocol by calling for a complete elimination of CFCs by the year 2000. [NASA Earth Observatory Glossary]

Definition 4: Any substance listed as Class I group I or Class I group III in 40 CFR part 82, appendix A to subpart A.Class II. [40 CFR 82.62 (CFR 2013)]

Definition 5: Compound consisting of chlorine, fluorine, and carbon. Chlorofluorocarbons (CFCs) are very stable in the troposphere. They move to the stratosphere and are broken down by strong ultraviolet light, where they release chlorine atoms that then deplete the ozone layer. CFCs were commonly used as refrigerants, solvents, and foam blowing agents. The most common CFCs were CFC-11, CFC-12, CFC-113, CFC-114, and CFC-115. CFCs have been phased out in the United States, with a few exceptions. [Ozone Layer Protection Glossary]

Definition 6: Gases covered under the 1987 Montreal Protocol and used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants. Since they are not destroyed in the lower atmosphere, CFCs drift into the upper atmosphere where, given suitable conditions, they break down ozone. These gases are being replaced by other compounds: hydrochlorofluorocarbons, an interim replacement for CFCs that are also covered under the Montreal Protocol, and hydrofluorocarbons, which are covered under the Kyoto Protocol. All these substances are also greenhouse gases.[Glossary of Climate Change Terms]

Definition 1: Any fluorinated GHG, CFC, or HCFC. [40 CFR 98.128 (CFR 2013)]

Definition 2: Powerful synthetic greenhouse gases such as hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for stratospheric ozone-depleting substances (e.g., chlorofluorocarbons, hydrochlorofluorocarbons, and halons) and are often used in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants. These gases are emitted in small quantities compared to carbon dioxide (CO₂), methane (CH₄), or nitrous oxide (N₂O), but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (High GWP gases)[Glossary of Climate Change Terms]

Definition: Five haloacetic acid constituents are monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid. Haloacetic acids occur when naturally-occurring organic and inorganic materials in the water react with the disinfectants, chlorine and chloramine. [EPA Basic Information about Disinfection Byproducts in Drinking Water: Total Trihalomethanes, Haloacetic Acids, Bromate, and Chlorite at http://water.epa.gov/drink/contaminants/basicinformation/disinfectionbyproducts.cfm]

Definition 1: Any of the Class I, Group II substances listed in subpart A, appendix A of 40 CFR part 82. This group consists of the three halogenated hydrocarbons known as Halon 1211, Halon 1301, and Halon 2402, and all isomers of these chemicals. [40 CFR 82.260 (CFR 2013)]

Definition 2: Compound consisting of bromine, fluorine, and carbon. Halons are used as fire extinguishing agents, both in built-in systems and in handheld portable fire extinguishers. Halon production in the U.S. ended on December 31, 1993, because they contribute to ozone depletion. [Ozone Layer Protection Glossary]

Definition 1: Compounds containing only hydrogen, fluorine, and carbon atoms. They were introduced as alternatives to ozone depleting substances in serving many industrial, commercial, and personal needs. HFCs are emitted as by-products of industrial processes and are also used in manufacturing. They do not significantly deplete the stratospheric ozone layer, but they are powerful greenhouse gases. [Greenhouse Emissions Glossary]

Definition 2: Any substance listed as class II in 40 CFR part 82, appendix B to subpart A. [40 CFR 82.302 (CFR 2013)] [40 CFR 82.62 (CFR 2013)]

Definition 3: Class of GHGs consisting of hydrogen, fluorine, and carbon. [40 CFR 98.6 (CFR 2013)]

Definition 4: Compound consisting of hydrogen, chlorine, fluorine, and carbon. Hydrochlorofluorocarbons (HCFCs) are one class of chemicals that was used to replace the chlorofluorocarbons (CFCs). They contain chlorine and thus deplete stratospheric ozone, but to a much lesser extent than CFCs. HCFCs have ozone depletion potentials (ODPs) ranging from 0.01 to 0.1. Production of HCFCs is being phased out. [Ozone Layer Protection Glossary]

Definition 5: Compounds containing hydrogen, fluorine, chlorine, and carbon atoms. Although ozone depleting substances, they are less potent at destroying stratospheric ozone than chlorofluorocarbons (CFCs). They have been introduced as temporary replacements for CFCs and are also greenhouse gases. [Glossary of Climate Change Terms]

Definition 1: Compounds containing only hydrogen, fluorine, and carbon atoms. They were introduced as alternatives to ozone depleting substances in serving many industrial, commercial, and personal needs. HFCs are emitted as by-products of industrial processes and are also used in manufacturing. They do not significantly deplete the stratospheric ozone layer, but they are powerful greenhouse gases with global warming potentials ranging from 140 (HFC-152a) to 11,700 (HFC-23). [Greenhouse Emissions Glossary][Glossary of Climate Change Terms]

Definition 2: Class of GHGs consisting of hydrogen, fluorine, and carbon. [40 CFR 98.6 (CFR 2013)]

Definition 3: Compound consisting of hydrogen, fluorine, and carbon. Hydrofluorocarbons (HFCs) are a class of replacements for chlorofluorocarbons. Because they do not contain chlorine or bromine, they do not deplete the ozone layer. All HFCs have an ozone depletion potential of 0. Some HFCs have high global warming potentials. [Ozone Layer Protection Glossary]

Definition 1: A fully fluorinated or perfluorinated chemical is one in which all the carbon-hydrogen bonds in a chain have been replaced by carbon-fluorine ones. All fully fluorinated chemicals are man-made. Example include perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) [EPA OPPT Glossary]

Definition 2: PFCs are a large group of manufactured compounds that are widely used to make everyday products more resistant to stains, grease, and water. For example, PFCs may be used to keep food from sticking to cookware, to make sofas and carpets resistant to stains, to make clothes and mattresses more waterproof, and may also be used in some food packaging, as well as in some firefighting materials. Because they help reduce friction, they are also used in a variety of other industries, including aerospace, automotive, building and construction, and electronics. [NIH National Institute of Environmental Health Sciences Perfluorinated Chemicals at https://www.niehs.nih.gov/health/materials/perflourinated_chemicals_508.pdf]

Definition 1: A very reactive and highly toxic green, gaseous element, belonging to the halogen family of substances. It is one of the most widespread elements, as it occurs naturally in sea-water, salt lakes and underground deposits, but usually occurs in a safe form as common salt (NaCl). Commercially it is used in large quantities by the chemical industry both as an element to produce chlorinated organic solvents, like polychlorinated biphenyls (PCBs), and for the manufacture of polyvinyl chloride plastics, thermoplastic and hypochlorite bleaches. Chlorine was the basis for the organochlorine pesticides, like DDT and other agricultural chemicals that have killed wildlife. The reactivity of chlorine has proved disastrous for the ozone layer and has been the cause of the creation of the ozone hole, which was first detected in the Southern Hemisphere over Antarctica and then over the Northern Hemisphere. (Source: WRIGHT) [GEneral Multilingual Environmental Thesaurus]

Definition 2: •Chlorine is an element used in industry and found in some household products. •Chlorine is sometimes in the form of a poisonous gas. Chlorine gas can be pressurized and cooled to change it into a liquid so that it can be shipped and stored. When liquid chlorine is released, it quickly turns into a gas that stays close to the ground and spreads rapidly. •Chlorine gas can be recognized by its pungent, irritating odor, which is like the odor of bleach. The strong smell may provide adequate warning to people that they are exposed. •Chlorine gas appears to be yellow-green in color. •Chlorine itself is not flammable, but it can react explosively or form explosive compounds with other chemicals such as turpentine and ammonia. [CDC Emergency Preparedness and Response Chemical Categories A-Z]

Definition: Bicyclic structure consisting of fused benzene and azepine rings; many compounds with this structure react with biogenicamine receptors, and so are psychotropic and neurotropic. [National Cancer Institute Metathesaurus]

Definition: Biphenyl compounds. Class of compounds containing two linked benzene rings. [Adapted from National Cancer Institute Metathesaurus]

Definition: Organic compounds containing carbon and hydrogen in the form of an unsaturated, usually hexagonal ring structure. Monocyclic compounds have a single ring. [Adapted from NLM Medical Subject Headings (MeSH)]

Definition: Benzene derivatives that include one or more hydroxyl groups attached to the ring structure. [NLM Medical Subject Headings (MeSH)]

Definition 1: A major group of unsaturated cyclic hydrocarbons containing two or more rings. The vast number of compounds of this important group, derived chiefly from petroleum and coal tar, are rather highly reactive and chemically versatile. The name is due to the strong and not unpleasant odor characteristic of most substances of this nature. (From Hawley's Condensed Chemical Dictionary, 12th ed, p96) [NLM Medical Subject Headings (MeSH)]

Definition 2: A chemical contaminant that forms when gas, coal and oil are burned. PAHs are common in areas with high rates of development and motor vehicle traffic. [Chesapeake Bay Glossary]Class of hydrocarbon compounds whose molecular structure includes two or more aromatic rings.[40 CFR 79.50 (CFR 2013)]

Definition 3: A group of organic chemicals that includes several petroleum products and their derivatives. [Contaminated Sediments (G/A)]

Definition 4: A class of organic compounds with a fused-ring aromatic structure. PAHs result from incomplete combustion of organic carbon (including wood), municipal solid waste, and fossil fuels, as well as from natural or anthropogenic introduction of uncombusted coal and oil. PAHs include benzo(a)pyrene, fluoranthene, and pyrene. [USGS National Water-Quality Assessment (NAWQA) Program Glossary]

Definition 5: PAHs are a class of organic compounds produced by incomplete combustion or high-pressure processes. PAHs form when complex organic substances are exposed to high temperatures or pressures. Often, PAHs consist of three or more fused benzene rings containing only carbon and hydrogen (Figure 1). Differences in the configuration of rings may lead to differences in properties.[Agency for Toxic Substances and Disease Registry Toxicity of Polycyclic Aromatic Hydrocarbons (PAHs) at http://www.atsdr.cdc.gov/csem/pah/docs/pah.pdf]

Definition 1: Organic matter extractable by methylene chloride as determined by Method 315 in appendix A to this part or by an approved alternative method. [40 CFR 63.842 (CFR 2013)]

Definition 2: Defines a broad class of compounds that includes polycyclic aromatic hydrocarbons. Polycyclic organic matter (POM) compounds are formed primarily from combustion and are present in the atmosphere in particulate form. Sources of air emissions are diverse and include vehicle exhausts, forest fires and wildfires, asphalt roads, coal, coal tar, coke ovens, agricultural burning, residential wood burning, and hazardous waste sites. Not all POM reported to EPA's National Emission Inventory is speciated. As a result, EPA applies some simplifying assumptions to model and assess the risk from the individual pollutants that comprise polycyclic organic matter. [National Air Toxics Assessment (NATA) Glossary]

Definition 3: A broad class of compounds that form mainly from combustion and are present in the air as particles. Sources of POM emissions include: vehicle exhaust; forest fires and wildfires; asphalt roads; coal; coal tar; coke ovens; agricultural burning; residential wood burning; and hazardous waste sites.[National Air Toxics Assessment (NATA) Glossary]

Definition: A group of tetraterpenes, with four terpene units joined head-to-tail. Biologically active members of this class are used clinically in the treatment of severe cystic ACNE; PSORIASIS; and other disorders of keratinization. [NLM Medical Subject Headings (MeSH)]

Definition 1: Salts or ions of the theoretical carbonic acid, containing the radical CO2(3-). Carbonates are readily decomposed by acids. The carbonates of the alkali metals are water-soluble; all others are insoluble. (From Grant & Hackh's Chemical Dictionary, 5th ed) [NLM Medical Subject Headings (MeSH)]

Definition 2: Compounds containing the radical CO3 −2. Upon calcination, the carbonate radical decomposes to evolve carbon dioxide (CO2). Common carbonates consumed in the mineral industry include calcium carbonate (CaCO3) or calcite; magnesium carbonate (MgCO3) or magnesite; and calcium-magnesium carbonate (CaMg(CO3)2) or dolomite. [40 CFR 98.6 (CFR 2013)]

Definition: Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical. [NLM Medical Subject Headings (MeSH)]

Definition: Certain chemical compounds containing phosphorus. [Terms of Environment]

Definition: The different physical forms for elemental carbon.

Definition 1: CAS 124-38-9. A colorless, odorless, non-poisonous gas that is a normal part of the ambient air. Carbon dioxide is a product of fossil fuel combustion. Although carbon dioxide does not directly impair human health, it is a greenhouse gas that traps terrestrial (i.e., infrared) radiation and contributes to the potential for global warming. [Greenhouse Emissions Glossary]

Definition 2: CO2. [40 CFR 98.6 (CFR 2013)]

Definition 3: A colorless, odorless, incombustible gas, present in the atmosphere and formed during respiration, usually obtained from coal, coke, or natural gas by combustion, from carbohydrates by fermentation, by reaction of acid with limestone or other carbonates, or naturally from springs. [USGS Energy Resources Program Energy Glossary & Acronym List]

Definition 4: A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes. It is the principal human caused greenhouse gas that affects the Earth's radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a Global Warming Potential of 1.[Glossary of Climate Change Terms]

Definition 1: A pungent colorless gaseous alkaline compound of nitrogen and hydrogen NH3 that is very soluble in water and can easily be condensed to a liquid by cold and pressure. [NIH Genetics Home Reference Glossary]

Definition 2: A colorless gaseous alkaline compound that is very soluble in water, has a characteristic pungent odour, is lighter than air, and is formed as a result of the decomposition of most nitrogenous organic material. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 3: A compound of nitrogen and hydrogen (NH3) that is a common by-product of animal waste. Ammonia readily converts to nitrate in soils and streams. [USGS National Water-Quality Assessment (NAWQA) Program Glossary]

Definition 4: A colorless, pungent, gas (NH3) that is extremely soluble in water, may be used as a refrigerant; a fixed nitrogen form suitable as fertilizer. [DOE Office of Energy Efficiency & Renewable Energy Glossary of Energy-Related Terms]

Definition 5: NH3 [40 CFR 58.1 (CFR 2013)]

Definition 6: One of the most abundant nitrogen-containing compounds in the atmosphere. It is an irritant with a characteristic pungent odor, which is widely used in industry. It is used in fertilizers to serve as a source of nitrogen for plants. [Community Multiscale Air Quality (CMAQ) Glossary]

Definition 1: Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and from power stations. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences; they are thus considered pollutants. [Climate Change Glossary]

Definition 2: All oxides of nitrogen except nitrous oxide, as measured by test methods set forth in this part. [40 CFR 60.2 (CFR 2013)]

Definition 3: Sum of nitric oxide and nitrogen dioxide in the flue gas or emission point, collectively expressed as nitrogen dioxide.[40 CFR 51.900 (CFR 2013)][40 CFR 51.1100 (CFR 2013)]

Definition 4: Nitric oxide and nitrogen dioxide. Oxides of nitrogen are expressed quantitatively as if the nitric oxide were in the form of nitrogen dioxide (oxides of nitrogen are assumed to have a molecular weight equivalent to nitrogen dioxide). [40 CFR 92.2 (CFR 2013)] [40 CFR 94.2 (CFR 2013)]

Definition 5: Meaning given in 40 CFR 1065.1001. [40 CFR 1039.801 (CFR 2013)][40 CFR 1042.901 (CFR 2013)][40 CFR 1033.901 (CFR 2013)][40 CFR 1036.801 (CFR 2013)][40 CFR 1037.801 (CFR 2013)][40 CFR 1045.801 (CFR 2013)][40 CFR 1048.801 (CFR 2013)][40 CFR 1051.801 (CFR 2013)][40 CFR 1054.801 (CFR 2013)]

Definition 6: NO and NO2 as measured by the procedures specified in § 1065.270. Oxides of nitrogen are expressed quantitatively as if the NO is in the form of NO2, such that you use an effective molar mass for all oxides of nitrogen equivalent to that of NO2.[40 CFR 1065.1001 (CFR 2013)]

Definition 7: Sum of nitric oxide (NO) and nitrogen dioxide (NO2) in the flue gas, expressed as nitrogen dioxide. [40 CFR 49.5512 (CFR 2013)]

Definition 8: Sum of nitrogen oxide (NO) and nitrogen dioxide (NO2) in the flue gas, expressed as nitrogen dioxide.[40 CFR 49.5513 (CFR 2013)]

Definition 9: Oxides of nitrogen and is defined as the sum of the concentrations of NO2 and NO. [40 CFR 58.1 (CFR 2013)] [40 CFR 53.1 (CFR 2013)]

Definition 10: Nitrogen oxide.[40 CFR 53.1 (CFR 2013)]

Definition 11: Oxides of nitrogen and is defined as the sum of the concentrations of NO2 and NO. [40 CFR 58.1 (CFR 2013)] [40 CFR 53.1 (CFR 2013)]

Definition 12: Generic term for the nitrogen oxides that are most relevant for air pollution, namely nitric oxide (NO) and nitrogen dioxide (NO₂). These gases contribute to the formation of smog and acid rain, as well as tropospheric ozone. [Community Multiscale Air Quality (CMAQ) Glossary]

Definition 13: Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and from power stations. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences; they are thus considered pollutants.[Glossary of Climate Change Terms]

Definition 14: Sum of nitric oxide and nitrogen dioxide in the flue gas or emission point, collectively expressed as nitrogen dioxide.[40 CFR 51.1300 (CFR 2019)]

Definition: Inorganic oxides of sulfur. [NLM Medical Subject Headings (MeSH)]

Definition: Group IA elements of the periodic table. Includes sodium and potassium among others. Generally reactive metals.

Definition: Any of the divalent electropositive metals beryllium, magnesium, calcium, strontium, barium, and radium, belonging to group 2A of the periodic table. (Source: CED) [GEneral Multilingual Environmental Thesaurus]

Definition 1: Any of a large number of substances having metallic properties and consisting of two or more elements; with few exceptions, the components are usually metallic elements. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 2: Mixture containing mostly metals. For example, brass is an alloy of copper and zinc. Steel contains iron and other metals but also carbon.[DOE Office of Energy Efficiency & Renewable Energy Fuel Cell Technologies Glossary]

Definition: A soft, lightweight metal that occurs naturally in the environment. Many things are made out of aluminum, including soda cans, automobile parts, and electrical equipment. [Acid Rain Student Glossary]

Definition 1: Metallic elements, such as mercury, lead, nickel, zinc, and cadmium, that are of environmental concern because they do not degrade over time. Although many are necessary nutrients, they are sometimes magnified in the food chain and in high concentrations can be toxic to life. [Watershed Protection Glossary]

Definition 2: A metal whose specific gravity is approximately 5.0 or higher. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 3: A metal having a specific gravity of 5.0 or greater. Heavy metals are generally toxic to organisms in relatively low concentrations, and tend to accumulate in the food web. Examples include arsenic, cadmium, chromium, lead, and mercury. [NOAA Coral Reef Glossary]

Definition 4: Any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. [Chesapeake Bay Program Glossary]

Definition 5: All uranium, plutonium, or thorium placed into a nuclear reactor.[40 CFR 191.12 (CFR 2018)]

Definition 1: Any pure metal other than iron or any metal alloy for which an element other than iron is its major constituent by percent in weight. [40 CFR 63.10692 (CFR 2013)][40 CFR 63.10906 (CFR 2013)]

Definition 2: Pure metal other than iron or any metal alloy for which a metal other than iron is its major constituent in percent by weight. [40 CFR 471.02 (CFR 2013)]

Definition: Elements scandium, yttrium, and lanthanum to lutetium, inclusive. [40 CFR 421.271 (CFR 2013)]

Definition: An iron-base alloy containing carbon, manganese, and often other alloying elements. Steel is defined here to include only those iron-carbon alloys containing less than 1.2 percent carbon by weight. [40 CFR 464.31 (CFR 2013)]

Definition: Metallic elements in which the members have the filling of the outermost shell to 8 electrons interrupted to bring the penultimate shell from 8 to 18 or 32 electrons; includes elements 21 through 29 (scandium through copper), 39 through 47 (yttrium through silver), 57 through 79 (lanthanum through gold), and all known elements from 89 (actinium) on. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition: A solution of hydrogen chloride gas in water; a poisonous, pungent liquid forming a constant-boiling mixture at 20% concentration in water; widely used as a reagent, in organic synthesis, in acidizing oil wells, ore reduction, food processing, and metal cleaning and pickling. Also known as muriatic acid. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 1: A highly reactive oxidizing agent obtained by distilling a nitrate with sulfuric acid. [NOAA Paleoclimatology Climate Glossary]

Definition 2: Nitric acid (HNO3). A colorless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. (From Merck Index, 11th ed) [NLM Medical Subject Headings (MeSH)]

Definition 3: HNO3 [40 CFR 58.1 (CFR 2013)]

Definition: Salt of alkyl or aryl derivatives of phosphorus trihydroxide (P(OH)3) and its tautomeric form dihydroxyphosphine oxide (HP=O(OH)2). [Adapted from NLM Medical Subject Headings (MeSH)]

Definition 1: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted the use of asbestos in manufacturing and construction. [Environmental Issues Glossary]

Definition 2: Generic name for a group of fibrous mineral silicates. It includes blue asbestos (crocidolite), white asbestos (chrysotile) and brown asbestos (amosite). After they are mined the asbestos fibres are separated from the rock and are spun into a cloth. When inhaled the fibres penetrate the lungs and the tissues of the bronchial tubes, resulting in asbestosis, a crippling lung disease. Asbestos also causes cancer of the lung and the gastro-intestinal tract, and mesothelioma, a malignant cancer of the inner lining of the chest. However, because it is a poor conductor of electricity and highly resistant to heat it has been widely used over the years in fire-fighting suits, and building and insulating materials. The fibrous form of several silicate minerals, at one time widely used for electrical and thermal insulation; the use of all forms of asbestos is now either banned or strictly controlled in many countries since it causes cancer. (Source: WRIGHT / ALL) [GEneral Multilingual Environmental Thesaurus]

Definition 3: The asbestiform varieties of serpentinite (chrysotile), riebeckite (crocidolite), cummingtonitegrunerite, anthophyllite, and actinolite-tremolite. (40 CFR 61.141) [DOE Glossary of Terms Related to CERCLA, EPCRA, PPA, RCRA and TSCA at http://homer.ornl.gov/sesa/environment/guidance/cercla/gloss97.pdf]

Definition 4: A group of naturally occurring minerals that separate into long, thin fibers. Asbestos was used for many years to insulate and fireproof buildings. In the 1989 CBECS, information on asbestos in buildings was collected (Section R of the Buildings Questionnaire) for the U.S. Environmental Protection Agency (EPA). Asbestos treatment methods include removal, encapsulation or sealing, and enclosure behind a permanent barrier. [DOE Energy Information Administration Glossary]

Definition 5: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction. [Federal Remediation Technologies Roundtable Glossary]

Definition 6: Asbestiform varieties of: Chrysotile (serpentine); crocidolite (riebeckite); amosite (cum- mingtonitegrunerite); anthophyllite; tremolite; and actinolite. [40 CFR 763.83 (CFR 2013)]

Definition: A solution of hydrogen chloride gas in water; a poisonous, pungent liquid forming a constant-boiling mixture at 20% concentration in water; widely used as a reagent, in organic synthesis, in acidizing oil wells, ore reduction, food processing, and metal cleaning and pickling. Also known as muriatic acid. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 1: A highly reactive oxidizing agent obtained by distilling a nitrate with sulfuric acid. [NOAA Paleoclimatology Climate Glossary]

Definition 2: Nitric acid (HNO3). A colorless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. (From Merck Index, 11th ed) [NLM Medical Subject Headings (MeSH)]

Definition 3: HNO3 [40 CFR 58.1 (CFR 2013)]

Definition: Salt of alkyl or aryl derivatives of phosphorus trihydroxide (P(OH)3) and its tautomeric form dihydroxyphosphine oxide (HP=O(OH)2). [Adapted from NLM Medical Subject Headings (MeSH)]

Definition 1: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted the use of asbestos in manufacturing and construction. [Environmental Issues Glossary]

Definition 2: Generic name for a group of fibrous mineral silicates. It includes blue asbestos (crocidolite), white asbestos (chrysotile) and brown asbestos (amosite). After they are mined the asbestos fibres are separated from the rock and are spun into a cloth. When inhaled the fibres penetrate the lungs and the tissues of the bronchial tubes, resulting in asbestosis, a crippling lung disease. Asbestos also causes cancer of the lung and the gastro-intestinal tract, and mesothelioma, a malignant cancer of the inner lining of the chest. However, because it is a poor conductor of electricity and highly resistant to heat it has been widely used over the years in fire-fighting suits, and building and insulating materials. The fibrous form of several silicate minerals, at one time widely used for electrical and thermal insulation; the use of all forms of asbestos is now either banned or strictly controlled in many countries since it causes cancer. (Source: WRIGHT / ALL) [GEneral Multilingual Environmental Thesaurus]

Definition 3: The asbestiform varieties of serpentinite (chrysotile), riebeckite (crocidolite), cummingtonitegrunerite, anthophyllite, and actinolite-tremolite. (40 CFR 61.141) [DOE Glossary of Terms Related to CERCLA, EPCRA, PPA, RCRA and TSCA at http://homer.ornl.gov/sesa/environment/guidance/cercla/gloss97.pdf]

Definition 4: A group of naturally occurring minerals that separate into long, thin fibers. Asbestos was used for many years to insulate and fireproof buildings. In the 1989 CBECS, information on asbestos in buildings was collected (Section R of the Buildings Questionnaire) for the U.S. Environmental Protection Agency (EPA). Asbestos treatment methods include removal, encapsulation or sealing, and enclosure behind a permanent barrier. [DOE Energy Information Administration Glossary]

Definition 5: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction. [Federal Remediation Technologies Roundtable Glossary]

Definition 6: Asbestiform varieties of: Chrysotile (serpentine); crocidolite (riebeckite); amosite (cum- mingtonitegrunerite); anthophyllite; tremolite; and actinolite. [40 CFR 763.83 (CFR 2013)]

Definition 1: Salts or ions of the theoretical carbonic acid, containing the radical CO2(3-). Carbonates are readily decomposed by acids. The carbonates of the alkali metals are water-soluble; all others are insoluble. (From Grant & Hackh's Chemical Dictionary, 5th ed) [NLM Medical Subject Headings (MeSH)]

Definition 2: Compounds containing the radical CO3 −2. Upon calcination, the carbonate radical decomposes to evolve carbon dioxide (CO2). Common carbonates consumed in the mineral industry include calcium carbonate (CaCO3) or calcite; magnesium carbonate (MgCO3) or magnesite; and calcium-magnesium carbonate (CaMg(CO3)2) or dolomite. [40 CFR 98.6 (CFR 2013)]

Definition: Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical. [NLM Medical Subject Headings (MeSH)]

Definition: Certain chemical compounds containing phosphorus. [Terms of Environment]

Definition: The different physical forms for elemental carbon.

Definition 1: CAS 124-38-9. A colorless, odorless, non-poisonous gas that is a normal part of the ambient air. Carbon dioxide is a product of fossil fuel combustion. Although carbon dioxide does not directly impair human health, it is a greenhouse gas that traps terrestrial (i.e., infrared) radiation and contributes to the potential for global warming. [Greenhouse Emissions Glossary]

Definition 2: CO2. [40 CFR 98.6 (CFR 2013)]

Definition 3: A colorless, odorless, incombustible gas, present in the atmosphere and formed during respiration, usually obtained from coal, coke, or natural gas by combustion, from carbohydrates by fermentation, by reaction of acid with limestone or other carbonates, or naturally from springs. [USGS Energy Resources Program Energy Glossary & Acronym List]

Definition 4: A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes. It is the principal human caused greenhouse gas that affects the Earth's radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a Global Warming Potential of 1.[Glossary of Climate Change Terms]

Definition 1: A pungent colorless gaseous alkaline compound of nitrogen and hydrogen NH3 that is very soluble in water and can easily be condensed to a liquid by cold and pressure. [NIH Genetics Home Reference Glossary]

Definition 2: A colorless gaseous alkaline compound that is very soluble in water, has a characteristic pungent odour, is lighter than air, and is formed as a result of the decomposition of most nitrogenous organic material. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 3: A compound of nitrogen and hydrogen (NH3) that is a common by-product of animal waste. Ammonia readily converts to nitrate in soils and streams. [USGS National Water-Quality Assessment (NAWQA) Program Glossary]

Definition 4: A colorless, pungent, gas (NH3) that is extremely soluble in water, may be used as a refrigerant; a fixed nitrogen form suitable as fertilizer. [DOE Office of Energy Efficiency & Renewable Energy Glossary of Energy-Related Terms]

Definition 5: NH3 [40 CFR 58.1 (CFR 2013)]

Definition 6: One of the most abundant nitrogen-containing compounds in the atmosphere. It is an irritant with a characteristic pungent odor, which is widely used in industry. It is used in fertilizers to serve as a source of nitrogen for plants. [Community Multiscale Air Quality (CMAQ) Glossary]

Definition 1: Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and from power stations. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences; they are thus considered pollutants. [Climate Change Glossary]

Definition 2: All oxides of nitrogen except nitrous oxide, as measured by test methods set forth in this part. [40 CFR 60.2 (CFR 2013)]

Definition 3: Sum of nitric oxide and nitrogen dioxide in the flue gas or emission point, collectively expressed as nitrogen dioxide.[40 CFR 51.900 (CFR 2013)][40 CFR 51.1100 (CFR 2013)]

Definition 4: Nitric oxide and nitrogen dioxide. Oxides of nitrogen are expressed quantitatively as if the nitric oxide were in the form of nitrogen dioxide (oxides of nitrogen are assumed to have a molecular weight equivalent to nitrogen dioxide). [40 CFR 92.2 (CFR 2013)] [40 CFR 94.2 (CFR 2013)]

Definition 5: Meaning given in 40 CFR 1065.1001. [40 CFR 1039.801 (CFR 2013)][40 CFR 1042.901 (CFR 2013)][40 CFR 1033.901 (CFR 2013)][40 CFR 1036.801 (CFR 2013)][40 CFR 1037.801 (CFR 2013)][40 CFR 1045.801 (CFR 2013)][40 CFR 1048.801 (CFR 2013)][40 CFR 1051.801 (CFR 2013)][40 CFR 1054.801 (CFR 2013)]

Definition 6: NO and NO2 as measured by the procedures specified in § 1065.270. Oxides of nitrogen are expressed quantitatively as if the NO is in the form of NO2, such that you use an effective molar mass for all oxides of nitrogen equivalent to that of NO2.[40 CFR 1065.1001 (CFR 2013)]

Definition 7: Sum of nitric oxide (NO) and nitrogen dioxide (NO2) in the flue gas, expressed as nitrogen dioxide. [40 CFR 49.5512 (CFR 2013)]

Definition 8: Sum of nitrogen oxide (NO) and nitrogen dioxide (NO2) in the flue gas, expressed as nitrogen dioxide.[40 CFR 49.5513 (CFR 2013)]

Definition 9: Oxides of nitrogen and is defined as the sum of the concentrations of NO2 and NO. [40 CFR 58.1 (CFR 2013)] [40 CFR 53.1 (CFR 2013)]

Definition 10: Nitrogen oxide.[40 CFR 53.1 (CFR 2013)]

Definition 11: Oxides of nitrogen and is defined as the sum of the concentrations of NO2 and NO. [40 CFR 58.1 (CFR 2013)] [40 CFR 53.1 (CFR 2013)]

Definition 12: Generic term for the nitrogen oxides that are most relevant for air pollution, namely nitric oxide (NO) and nitrogen dioxide (NO₂). These gases contribute to the formation of smog and acid rain, as well as tropospheric ozone. [Community Multiscale Air Quality (CMAQ) Glossary]

Definition 13: Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and from power stations. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences; they are thus considered pollutants.[Glossary of Climate Change Terms]

Definition 14: Sum of nitric oxide and nitrogen dioxide in the flue gas or emission point, collectively expressed as nitrogen dioxide.[40 CFR 51.1300 (CFR 2019)]

Definition: Inorganic oxides of sulfur. [NLM Medical Subject Headings (MeSH)]

Definition: Group IA elements of the periodic table. Includes sodium and potassium among others. Generally reactive metals.

Definition: Any of the divalent electropositive metals beryllium, magnesium, calcium, strontium, barium, and radium, belonging to group 2A of the periodic table. (Source: CED) [GEneral Multilingual Environmental Thesaurus]

Definition 1: Any of a large number of substances having metallic properties and consisting of two or more elements; with few exceptions, the components are usually metallic elements. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 2: Mixture containing mostly metals. For example, brass is an alloy of copper and zinc. Steel contains iron and other metals but also carbon.[DOE Office of Energy Efficiency & Renewable Energy Fuel Cell Technologies Glossary]

Definition: A soft, lightweight metal that occurs naturally in the environment. Many things are made out of aluminum, including soda cans, automobile parts, and electrical equipment. [Acid Rain Student Glossary]

Definition 1: Metallic elements, such as mercury, lead, nickel, zinc, and cadmium, that are of environmental concern because they do not degrade over time. Although many are necessary nutrients, they are sometimes magnified in the food chain and in high concentrations can be toxic to life. [Watershed Protection Glossary]

Definition 2: A metal whose specific gravity is approximately 5.0 or higher. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 3: A metal having a specific gravity of 5.0 or greater. Heavy metals are generally toxic to organisms in relatively low concentrations, and tend to accumulate in the food web. Examples include arsenic, cadmium, chromium, lead, and mercury. [NOAA Coral Reef Glossary]

Definition 4: Any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. [Chesapeake Bay Program Glossary]

Definition 5: All uranium, plutonium, or thorium placed into a nuclear reactor.[40 CFR 191.12 (CFR 2018)]

Definition 1: Any pure metal other than iron or any metal alloy for which an element other than iron is its major constituent by percent in weight. [40 CFR 63.10692 (CFR 2013)][40 CFR 63.10906 (CFR 2013)]

Definition 2: Pure metal other than iron or any metal alloy for which a metal other than iron is its major constituent in percent by weight. [40 CFR 471.02 (CFR 2013)]

Definition: Elements scandium, yttrium, and lanthanum to lutetium, inclusive. [40 CFR 421.271 (CFR 2013)]

Definition: An iron-base alloy containing carbon, manganese, and often other alloying elements. Steel is defined here to include only those iron-carbon alloys containing less than 1.2 percent carbon by weight. [40 CFR 464.31 (CFR 2013)]

Definition: Metallic elements in which the members have the filling of the outermost shell to 8 electrons interrupted to bring the penultimate shell from 8 to 18 or 32 electrons; includes elements 21 through 29 (scandium through copper), 39 through 47 (yttrium through silver), 57 through 79 (lanthanum through gold), and all known elements from 89 (actinium) on. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition: Products of the reaction of calcium hydroxide with any acid.

Definition: Salts consisting of a sodium cation and an inorganic anion.

Definition: Inorganic compounds that contain magnesium as an integral part of the molecule. [NLM Medical Subject Headings (MeSH)]

Scope Note: KW Toxics 700-799

Definition: Chemical compounds used in anti-foulant paints to protect the hulls of boats and ships, buoys and pilings from marine organisms such as barnacles. (Source: EPAGLO) [GEneral Multilingual Environmental Thesaurus]

Definition: Pre-emergent herbicides.

Definition: Polymers where the main polymer chain comprises recurring amide groups. These compounds are generally formed from combinations of diamines, diacids, and amino acids and yield fibers, sheeting, or extruded forms used in textiles, gels, filters, sutures, contact lenses, and other biomaterials. [NLM Medical Subject Headings (MeSH)]

Definition: A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed) [NLM Medical Subject Headings (MeSH)]

Definition: A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed) [National Cancer Institute Metathesaurus]

Definition: Thermoplastic polymer or copolymer comprised of at least 50 percent ethylene by weight; see low density polyethylene and high density polyethylene. [40 CFR 60.561 (CFR 2013)]

Definition 1: A polymer of styrene that is a rigid, transparent thermoplastic with good physical and electrical insulating properties, used in molded products, foams, and sheet materials. [DOE Energy Information Administration Glossary]

Definition 2: Thermoplastic polymer or copolymer comprised of at least 80 percent styrene or para-methylstyrene by weight. [40 CFR 60.561 (CFR 2013)]

Definition: One or both of the following: (1) Amino resin; or(2) Phenolic resin. [40 CFR 63.1402 (CFR 2013)]

Definition 1: Resin which is produced by a polymerization process which initiates from free radical catalyst sites and is sold undried.[40 CFR 61.61 (CFR 2013)]

Definition 2: Colloidal aqueous emulsion of elastomer. A latex may be further processed into finished products by direct use as a coating or as a foam, or it may be precipitated to separate the rubber particles, which are then used in dry state to prepare finished products. [40 CFR 63.482 (CFR 2018)]

Definition: Styrenic terpolymers consisting primarily of acrylonitrile, 1,3-butadiene, and styrene monomer units. ABS is usually composed of a styrene-acrylonitrile copolymer continuous phase with dispersed butadiene derived rubber. [40 CFR 63.1312 (CFR 2013)]

Definition: Copolymers consisting primarily of styrene and acrylonitrile monomer units. [40 CFR 63.1312 (CFR 2013)]

Definition 1: Product of the oxidation of ethanol and of the destructive distillation of wood. It is used locally, occasionally internally, as a counterirritant and also as a reagent. (Stedman, 26th ed) [NLM Medical Subject Headings (MeSH)]

Definition 2: An acid with the structure of C2H4O2. Acetyl groups are bound through an ester linkage to hemicellulose chains—especially xylans—in wood and other plants. The natural moisture present in plants hydrolyzes the acetyl groups to acetic acid, particularly at elevated temperatures. [DOE Office of Energy Efficiency & Renewable Energy Bioenergy Glossary]

Definition: A solution of hydrogen chloride gas in water; a poisonous, pungent liquid forming a constant-boiling mixture at 20% concentration in water; widely used as a reagent, in organic synthesis, in acidizing oil wells, ore reduction, food processing, and metal cleaning and pickling. Also known as muriatic acid. (Source: MGH) [GEneral Multilingual Environmental Thesaurus]

Definition 1: A highly reactive oxidizing agent obtained by distilling a nitrate with sulfuric acid. [NOAA Paleoclimatology Climate Glossary]

Definition 2: Nitric acid (HNO3). A colorless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. (From Merck Index, 11th ed) [NLM Medical Subject Headings (MeSH)]

Definition 3: HNO3 [40 CFR 58.1 (CFR 2013)]

Definition: Salt of alkyl or aryl derivatives of phosphorus trihydroxide (P(OH)3) and its tautomeric form dihydroxyphosphine oxide (HP=O(OH)2). [Adapted from NLM Medical Subject Headings (MeSH)]

Definition: Any of a family of compounds which has as a nucleus a triple-ring structure consisting of two benzene rings connected through a pair of oxygen atoms. [40 CFR 766.3 (CFR 2013)]