Man-made, effects, processes, objects, or materials are those that are derived from human activities, as opposed to those occurring in natural environments without human influences.

Air quality action plan

Where a local authority has set up an AQMA, it must produce an action plan setting out the measures it intends to take in the designated area.

Air quality objectives

Objectives for air pollution are concentrations over a given time period that are acceptable in terms of their effect on health and the environment. They can also be used as indicators to see if air pollution is getting better or worse.

Air Quality Management Area (AQMA)

An area which a local authority had designated for action, based upon a prediction that Air Quality Objectives will be exceeded.


A lung condition characterised by inflammation and spasm of the airways. This causes intermittent breathing problems such as coughing, wheezing and shortness of breath. Asthma can be triggered by infections, allergies, exercise, air pollution, temperature changes and other irritants.

Air Pollutant

Any substance in the air that could, in high enough concentration, harm humans, animals, or plant life.


The mass of air surrounding the Earth.


The biosphere is the part of the earth and its atmosphere in which living organisms exist. It includes everything living on Earth, including humans, animals, and insects. In other words, the biosphere is everything that is alive on the earth.


A chemical process in which a substance reacts with oxygen to give heat and light in the form of either a glow or flames.


Light that is produced as the result of a chemical reaction.

Carbon Dioxide

A colourless, odourless non-combustible gas with the formula CO2 that is present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass) by respiration, and by the gradual decomposing of organic matter in the soil.


Any substance that has a definite molecular composition. For example, water (H2O) Is a chemical. It Is made up of molecules, each of which Is made up of two hydrogen atoms and one oxygen atom.


The amount of one substance dissolved or contained in a given amount of another. For example, seawater contains a higher concentration of salt than fresh water. The concentration of an air pollutant could be measured in the number of micrograms of the pollutant per cubic metre of air, which is written as µg m−³.

Diffusion tube

A small plastic tube that is placed outside and contains a metal gauze coated with a substance that absorbs nitrogen dioxide and can be analysed so that levels of the gas can be measured.


Pollutants that come into contact with the body and present a potential health threat. Exposure may be short term (acute) or long term (chronic).

Fine particles

See particles

Greenhouse Effect

The effect of the Earth’s atmosphere, due to certain gases, in trapping heat from the sun; the atmosphere acts like a greenhouse.

Greenhouse Gases

Gases that trap the heat of the sun in the Earth’s atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapour and carbon dioxide. Lesser greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrogen oxides.

Ground Level Ozone

Also known as ‘Smog’. It is formed by a chemical reaction between Volatile Organic Compounds (VOCs) and Nitrogen Oxides (NOx) in the presence of sunlight. Ground Level Ozone can reach unhealthy levels when the weather is hot and sunny with little or no wind.

Lung function

Lung function is a measure of how well the lungs take in and exhale air and how efficiently they transfer oxygen into the blood.


Written µm. A unit of length equal to one millionth (10−6) of a meter.

Particles, particulates or particulate matter (PM)

Tiny particles of solid or liquid suspended in a gas. They can be written to show the size of the particles, for example PM10 are particles that are 10 microns or less, PM2.5 are less than 2.5 microns.

Photochemical Smog

In 1905 Dr. H.A. Des Voeux used the term smog to describe the conditions of sooty or smoky fogs. These are usually associated with sulphur dioxide pollution and smoke pollution. There is also summertime smog, photochemical smog or haze. This occurs when there is a high level of ozone pollution.

(Air) Pollutant

An air pollutant can be classed as any impurity in the air that could have an unwanted effect on the environment or our health.

PM10, PM2.5

Particulate matter with aerodynamic diameters of up to 10 microns and 2.5 microns, respectively.

Primary pollutant

Substances that come directly from the source, for example carbon monoxide gas from a motor vehicle exhaust.

Secondary pollutants

are not emitted from a source but form in the air when primary pollutants react with other gases and particles.


The layer of the Earth’s atmosphere that lies above the troposphere and extends to about 50 km above the Earth’s surface. The temperature within the stratosphere remains fairly constant but can rise in the upper regions of this layer due to absorption of ultraviolet radiation by ozone.


In 1905 Dr. H.A. Des Voeux used the term smog to describe the conditions of sooty or smoky fogs. These are usually associated with sulphur dioxide pollution and smoke pollution. There is also summertime smog, photochemical smog or haze. This occurs when there is a high level of ozone pollution.


A general name for airborne solids, liquid particulates and gases emitted when a material undergoes combustion. Usually particles less than 15 microns in diameter.


The vapor formed when water changes from a liquid to a gas.


The layer of the atmosphere closest to the Earth’s surface. The troposphere extends from the Earth’s surface up to about 10-15 km.

Temperature Inversion

A condition when a layer of warm air traps a cooler layer of air beneath it. This prevents pollutants and other airborne substances from escaping into the atmosphere.

Volatile organic compounds

Volatile organic compounds are carbon-based emissions (other than CO and CO2), released through evaporation and/or combustion, that can react with nitrogen oxide in the presence of sunlight to form ozone.

Volcanic Dust

Fine particles of ash and rock suspended in the atmosphere after a volcanic eruption.

World Population

The total number of humans on Earth at a given time. In 2008 the world’s population was estimated to be 6.7 billion (6,700,000,000). If the world population continues to grow at its current rate it is expected to reach 9 billion by 2042.

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