AAS
Atomic absorption spectroscopy.

Abatement
Reducing the degree or intensity of, or eliminating, pollution.

Accreditation
Certification to an agreed standard of performance to a national or international standard.

ACCU
Automatic Cartridge Collection Unit.

Acid Deposition
A complex chemical and atmospheric phenomenon that occurs when emissions of sulphur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form. The wet forms, popularly called "acid rain," can fall as rain, snow, or fog. The dry forms are acidic gases or particulates.

Acidic
The condition of water or soil that contains a sufficient amount of acid substances to lower the pH below 7.0.

Activated Carbon
A highly adsorbent form of carbon used to remove odours and toxic substances from liquid or gaseous emissions. In waste treatment it is used to remove dissolved organic matter from wastewater. It is also used in motor vehicle evaporative control systems.

Activated Sludge
Product that results when primary effluent is mixed with bacteria-laden sludge and then agitated and aerated to promote biological treatment, speeding the breakdown of organic matter in raw sewage undergoing secondary waste treatment.

Acute Exposure
A single exposure to a toxic substance, which results in severe biological harm or death. Acute exposures are usually characterised as lasting no longer than a day, as compared to longer, continuing exposure over a period of time.

Acute Toxicity
The ability of a substance to cause poisonous effects resulting in severe biological harm or death soon after a single exposure or dose. Also, any severe poisonous effect resulting from a single short-term exposure to a toxic substance.

Add-on Control Device
An air pollution control device such as carbon absorber or incinerator that reduces the pollution in an exhaust gas.

AED
Aerodynamic Diameter.

Aerated Lagoon
A holding and/or treatment pond that speeds up the natural process of biological decomposition of organic waste by stimulating the growth and activity of bacteria that degrade organic waste.

Aeration Tank
A chamber used to inject air into water.

Aeration
A process, which promotes biological degradation of organic matter in water. The process may be passive (as when waste is exposed to air), or active (as when a mixing or bubbling device introduces the air).

Aerobic Treatment
Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth.

Aerobic
Life or processes that require, or are not destroyed by, the presence of oxygen. (See: anaerobic.)

Aerosol
A finely divided material suspended in air or other gaseous environment.

Aerosol
A suspension of liquid or solid particles in a gas.

Afterburner
In incinerator technology, a burner located so that the combustion gases are made to pass through its flame in order to remove smoke and odours. It may be attached to or be separated from the incinerator proper.

Air Contaminant
Any particulate matter, gas, or combination thereof, other than water vapour.

Air Plenum
Any space used to convey air in a building, furnace, or structure. The space above a suspended ceiling is often used as an air plenum.

Air Pollutant
Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases, or in combination.

Air Pollution Control Device
Mechanism or equipment that cleans emissions generated by an incinerator by removing pollutants that would otherwise be released to the atmosphere.

Air Pollution Episode
A period of abnormally high concentration of air pollutants, often due to low winds and temperature inversion, that can cause illness and death.

Air Pollution
The presence of contaminant or pollutant substances in the air that do not disperse properly and interfere with human health or welfare, or produce other harmful environmental effects.

Air Quality Monitoring
Sampling, measurement/analysis of airborne pollutants.

Air Quality Standards
The level of pollutants prescribed by regulations that are not to be exceeded during a given time in a defined area.

Airborne Particulates
Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Airborne particulates include: windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and motor vehicle or non-road engine exhausts.

Airborne Release
Release of any chemical into the air.

Alkaline
The condition of water or soil which contains a sufficient amount of alkali substance to raise the pH above 7.0.

Alkalinity
The capacity of water to neutralise acids.

Ambient Air
Any unconfined portion of the atmosphere: open air, surrounding air.

Ambient Temperature
Temperature of the surrounding air or other medium.

AMS
Automated Measuring System.

Anaerobic Decomposition
Reduction of the net energy level and change in chemical composition of organic matter caused by micro-organisms in an oxygen-free environment.

Anaerobic
A life or process that occurs in, or is not destroyed by, the absence of oxygen.

Aromatic
A type of hydrocarbon, such as benzene or toluene, added to gasoline in order to increase octane. Some aromatics are toxic.

Asbestos
A mineral fibre that can pollute air or water and cause cancer or asbestosis when inhaled.

Asbestosis
A disease associated with inhalation of asbestos fibres. The disease makes breathing progressively more difficult and can be fatal.

Ash
Incombustible residue left over after incineration or other thermal processes.

Ash
The mineral content of a product remaining after complete combustion.

Assay
A test for a particular chemical or effect.

Assessment
A way of evaluation or judging performance.

Asthma
A condition marked by laboured breathing, constriction of the chest, coughing and gasping usually brought on by allergies