Cadmium (Cd)
A heavy metal that accumulates in the environment. (see heavy metals)

Cap
A layer of clay, or other impermeable material installed over the top of a closed landfill to prevent entry of rainwater and minimise leachate.

Capillary Action
A phenomenon associated with the surface tension of a liquid that occurs in fine bore tubes and channels.

Capture Efficiency
The fraction of organic vapours generated by a process that are directed to an abatement or recovery device.

Carbon Absorber
An add-on control device that uses activated carbon to absorb volatile organic compounds (VOC) from a gas stream. (The VOC are later recovered from the carbon.).

Carbon Monoxide (CO)
A colourless, odourless, poisonous gas produced by incomplete combustion.

Carbon Sequestration
Capture and storage of carbon in a manner that prevents it from being released into the atmosphere for a specified period of time, the storage area is commonly referred to as a carbon sink.

Carbon Tetrachloride (CCl4)
Compound consisting of one carbon atom and four chlorine atoms, once widely used as a industrial raw material, as a solvent, and in the production of CFCs. Use as a solvent ended when it was discovered to be carcinogenic.

Carbon trading
The carbon trading scheme is designed to allow countries to buy and sell their quotas of carbon dioxide (CO2) emissions.

Carcinogen
Any substance that can cause or aggravate cancer.

Case Study
A brief fact sheet providing risk, cost, and performance information on alternative methods and other pollution prevention ideas, compliance initiatives, voluntary efforts, etc.

Catalyst
A substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed by the chemical reaction.

Catalytic Converter
An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by oxidising them into carbon dioxide and water or reducing them to nitrogen.

Catalytic Incinerator
A control device that oxidises volatile organic compounds (VOCs) by using a catalyst to promote the combustion process. Catalytic incinerators require lower temperatures than conventional thermal incinerators, thus saving fuel and other costs.

Cementitious
Densely packed and non-fibrous friable materials.

Characteristic
Any one of the four categories used in defining hazardous waste: ignitability, corrosivity, reactivity, and toxicity.

Chemical Compound
A distinct and pure substance formed by the union or two or more elements in definite proportion by weight.

Chemical Element
A fundamental substance comprising one kind of atom; the simplest form of matter.

Chemical Oxygen Demand (COD)
A measure of the oxygen required to oxidise all compounds, both organic and inorganic, in water.

Chlorinated Hydrocarbons
1. Chemicals containing only chlorine, carbon and hydrogen. These include a class of persistent, broad-spectrum insecticides that linger in the environment and accumulate in the food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride, and toxaphene. Other examples include TCE, used as an industrial solvent. 2. Any chlorinated organic compounds including chlorinated solvents such as dichloromethane, trichloromethylene, chloroform.

Chlorinated Solvent
An organic solvent containing chlorine atoms (e.g., methylene chloride and 1,1,1-trichloromethane). Uses of chlorinated solvents include aerosol spray containers, in highway paint, and dry cleaning fluids.

Chlorofluorocarbons (CFCs)
A family of inert, non-toxic, and easily liquefied chemicals used in refrigeration, air conditioning, packaging, insulation, or as solvents and aerosol propellants. Because CFCs are not destroyed in the lower atmosphere they drift into the upper atmosphere where their chlorine components destroy ozone.

Chromium
(See: heavy metals.)

Chronic Effect
An adverse effect on a human or animal in which symptoms recur frequently or develop slowly over a long period of time.

Chronic Exposur
Multiple exposures occurring over an extended period of time or over a significant fraction of an animal's or human's lifetime (Usually seven years to a lifetime.)

Climate Change (also referred to as 'global climate change')
The term 'climate change' is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, 'climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate.

Co-fire
Burning of two fuels in the same combustion unit; e.g., coal and natural gas, or oil and coal.

Coal Gasification
Conversion of coal to a gaseous product by one of several available technologies.

Cogeneration
The consecutive generation of useful thermal and electric energy from the same fuel source.

Coke Oven
An industrial process which converts coal into coke, one of the basic materials used in blast furnaces for the conversion of iron ore into iron.

Combustion
1. Burning, or rapid oxidation, accompanied by release of energy in the form of heat and light. 2. Refers to controlled burning of waste, in which heat chemically alters organic compounds, converting into stable inorganics such as carbon dioxide and water.

Combustion Chamber
The actual compartment where fuel or waste is burned in an incinerator or boiler.

Combustion Product
Substance produced during the burning or oxidation of a material.

Compaction
Reduction of the bulk of solid waste by rolling and tamping.

Compliance Monitoring
Collection and evaluation of data, including self-monitoring reports, and verification to show whether pollutant concentrations and loads contained in permitted discharges are in compliance with the limits and conditions specified in the permit.

Compost
The relatively stable humus material that is produced from a composting process in which bacteria in soil mixed with garbage and degradable trash break down the mixture into organic fertiliser.

Composting
The controlled biological decomposition of organic material in the presence of air to form a humus-like material. Controlled methods of composting include mechanical mixing and aerating, ventilating the materials by dropping them through a vertical series of aerated chambers, or placing the compost in piles out in the open air and mixing it or turning it periodically.

Construction and Demolition Waste
Waste building materials, dredging materials, tree stumps, and rubble resulting from construction, remodelling, repair, and demolition of homes, commercial buildings and other structures and pavements. May contain lead, asbestos, or other hazardous substances.

Contaminant
Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil.

Contamination
Introduction into water, air, and soil of micro-organisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the medium unfit for its next intended use. Also applies to surfaces of objects, buildings, and various household and agricultural use products.

Continuous Sample
A flow of water, gas, waste or other material from a particular place in a plant to the location where samples are collected for testing. May be used to obtain grab or composite samples.

Conventional Pollutants
Statutorily listed pollutants understood well by scientists. These may be in the form of organic waste, sediment, acid, bacteria, viruses, nutrients, oil and grease, or heat.

Cost/Benefit Analysis
A quantitative evaluation of the costs, which would have incurred by implementing an environmental regulation versus the overall benefits to society of the proposed action.

Cumulative Exposure
The sum of exposures of an organism to a pollutant over a period of time.

Cyclone Collector
A device that uses centrifugal action to remove large particles from polluted air.