GlossaryHeadingGlossaryDetails
AbatementThe reduction or elimination of pollution.
AbscissionIs the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed.
AbsorptionThe uptake of water or dissolved chemicals by cells or organisms.
Acid depositionA complex chemical and atmospheric phenomenon occurring when emissions of sulphur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from original sources, and then deposited on the earth in either a 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.
Acid RainA condition in which natural precipitation becomes acidic after reacting chemically with pollutants in air.
Acute exposureOne or a series of short-term exposures generally lasting less than 24 hours.
Acute exposureA single exposure to a toxic substance, which results in severe biological harm or death.
Acute Health EffectA health effect that occurs over a relatively short period of time (e.g., minutes or hours). The term is used to describe brief exposures and effects which appear promptly after exposure.
AdaptationAdaptation refers to adjustments in ecological, social, or economic systems in response to actual or expected climatic stimuli and their effects or impacts. It refers to changes in processes, practices, and structures to moderate potential damages or to benefit from opportunities associated with climate change.
AdsorptionAdsorption, the binding of molecules or particles to a surface, must be distinguished from absorption, the filling of pores in a solid. The most common industrial adsorbents are activated carbon, silica gel, and alumina, because they present enormous surface areas per unit weight.
AerobicLiving / occurring only in the presence of free oxygen.
AerosolA gaseous suspension of fine solid or liquid particles. Aerosols can be natural such as fog, forest exudates and geyser steam and cal also be artificial such as haze, dust, particulate air pollutants and smoke.
AfforestationThe planting of new forests on lands where the preceding vegetation or land did not contain forests.
Air MonitoringMonitoring is the systematic, long-term assessment of pollutant levels by measuring the quantity and types of certain pollutants in the surrounding, outdoor air.
Air pollutantAny solid, liquid or gaseous substance (including noise) present in the atmosphere in such concentration as may be or tend to be injurious to human beings or other creatures or plants or property or environment.
Air qualityIt means the state of the air around us. Good air quality refers to clean, clear, unpolluted air. Poor air quality is a result of a number of factors, including emissions from various sources, both natural and “human-caused.” Poor air quality occurs when pollutants reach high enough concentrations to endanger human health and/or the environment.
Air quality indexThe air quality index is a number indicating the air quality at a particular time in a particular area. The US EPA developed a uniform, standard index to make it easy to compare air quality in different parts of the country, and to avoid confusion for travellers and people who have moved from one area to another. This index was formerly called the pollutant standards index (PSI).
Air quality index (AQI)is a number used by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become.
Air Quality Standard (AQS)The prescribed level of a pollutant in the outside air that should not be exceeded during a specific time period to protect public health.
AlbedoThe ratio of the light reflected by a surface to that received by it.
Alternative FuelsFuels such as methanol, ethanol, natural gas and liquid petroleum gas that are cleaner burning and help to meet the mobile and stationary emission standards. These fuels may be used in place of less clean fuels for powering motor vehicles.
Ambient airAny unconfined portion of the atmosphere; open air, surrounding air.
Ambient qualityMaximum level of a specific pollutant allowed in air, water, soil or food.
Ambient temperatureTemperature of the surrounding air or other medium.
AnthropogenicThe term designates an effect or object resulting from human activity. Human impact on the environment includes impacts on biophysical environments, biodiversity, and other resources.
Anthropogenic emissionsEmissions of the greenhouse gases, greenhouse gas precursors and aerosols associated with human activities.
AshMineral content of a product that remains after complete combustion.
AsthmaAsthma is a chronic (long-term) lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling sound when you breathe), chest tightness, shortness of breath, and coughing.
AsthmaA chronic inflammatory disorder of the lungs characterized by wheezing, breathlessness, chest tightness and cough.
Atmosphereis a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).
Atmospheric stabilityIt is a measure of the atmosphere's tendency to encourage or deter vertical motion, and vertical motion is directly correlated to different types of weather systems and their severity. In unstable conditions, a lifted parcel of air will be warmer than the surrounding air at altitude.