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.
BaghouseAn air pollution control device that traps particulates by forcing gas streams through large permeable bags usually made of glass fibers.
BiodiversityIt is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet.
BiofuelA fuel (gas or liquid) produced from dry organic matter (biomass) or combustible product (as oil) of plants.
BiogasRefers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. It can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste.
BiomassTotal weight of living matter in a defined system such as a population, ecosystem, etc. It is usually expressed as dry weight per unit volume or area.
BronchitisIt is an inflammation of the lining of your bronchial tubes, which carry air to and from your lungs. It may be either acute (development of a cough or small sensation in the back of the throat, with or without the production of sputum) or chronic (presence of a productive cough that lasts for three months or more per year for at least two years).
CancerMalignant cellular growth consisting of genetically and functionally modified cells capable of invading other tissues.
Cancum agreementIt represent key steps forward in capturing plans to reduce greenhouse gas emissions and to help developing nations protect themselves from climate impacts and build their own sustainable futures.
Carbon creditA carbon credit is a generic term for any tradable certificate or permit representing the right to emit one tonne of carbon dioxide or the mass of another greenhouse gas with a carbon dioxide equivalent (tCO2e) equivalent to one tonne of carbon dioxide.
Carbon dioxideA minor constituent of air comprising about 0.32% of the atmosphere. It is essential to living systems, released by respiration and to a much lesser extent by volcanic activity and removed from the atmosphere by photosynthesis.
Carbon footprintIt is the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organization, or community.
Carbon Monoxide (CO)Colourless gas found in trace quantities in the natural atmosphere and produced by incomplete combustion, notably in motor cars. It forms a stable compound with blood haemoglobin, the carboxyhaemoglobin. It is harmless in small doses.
Carbon sequestrationThe removal and storage of carbon from the atmosphere by green plants through the process of photosynthesis, in which carbon dioxide is combined with water to form carbohydrates that can be stored in plant tissues
Carbon sinkAn area where the rate of carbon uptake by living organisms exceeds the rate of carbon release, so that carbon is sequestered in organic or organic forms.
CarcinogenSubstances that cause or promote the development of cancer (chemicals, ionizing radiations, viruses etc.)
Catalytic convertorIt is a vehicle emissions control device that converts toxic pollutants in exhaust gas to less toxic pollutants by catalyzing a redox reaction (oxidation or reduction). Catalytic converters are used in internal combustion engines fueled by either petrol (gasoline) or diesel
ChimneyA vertical channel or pipe which conducts smoke and combustion gases up from a fire or furnace and typically through the roof of a building.
Chlorofluorocarbons (CFCs)These are the compounds of carbon and halogens. There are several CFCs being used mainly as propellants in aerosol cans and as refrigerants in refrigerators, deep freezers and air conditioners, and also used in plastic foams.
ChlorosisIt is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green colour of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates through photosynthesis and may die.
ChronicA condition or disease that is persistent or otherwise long-lasting in its effects.
Clean Air ActIt is a United States federal law designed to control air pollution on a national level. It requires the Environmental Protection Agency (EPA) to develop and enforce regulations to protect the public from airborne contaminants known to be hazardous to human health.
Clean coal technologyAny technology, which will achieve significant reductions in pollutants, associated with the burning of coal.
Clean Development Mechanism (CDM)It is one of the flexibility mechanisms defined in the Kyoto Protocol (IPCC, 2007) that provides for emissions reduction projects which generate Certified Emission Reduction units which may be traded in emissions trading schemes.
ClimateLong-term weather conditions and factors peculiar to a given environmental segment/ area due to its geographical situation.
Climate changeAn alteration to measured quantities (Ex: precipitation, temperature, radiation, wind, cloudiness etc) within the climate system that departs significantly from previous average conditions and is seen to endure, bringing about corresponding changes to ecosystems and socio-economic activities.
CoalSolid, combustible mixture of organic compounds with 30% to 98% carbon by weight, mixed with various amounts of water and small amounts of sulphur and nitrogen compounds. It is formed in several stages as the remains of plants are subjected to heat and pressure over millions of years.
Coal gasificationConversion of solid coal to synthetic natural gas (SNG).
Coarse particlesCoarse particles are the relatively large airborne particles mainly produced by the mechanical break-up of even larger solid particles. Examples of coarse particles include dust, pollen, spores, fly ash, and plant and insect parts. Coarse particles have an aerodynamic diameter ranging from 2.5 to 10µm (PM10-2.5), which distinguishes them from the smaller airborne particulate matter referred to as fine (PM2.5) and ultrafine particles (PM0.1).
CombustionThe act or instance of burning some type of fuel, such as gasoline, to produce energy. Combustion is typically the process that powers automobile engines and power plant generators.
ConcentrationAmount of a chemical in a particular volume or weight of air, water, soil or other medium.
Control equipmentAny apparatus, device, equipment or system to control the quality and manner of emission of any air pollutant and includes any device used for securing the efficient operation of any industrial plant
Criteria Air PollutantAn air pollutant for which acceptable levels of exposure can be determined and for which an ambient air quality standard has been set. Examples include: ozone, carbon monoxide, nitrogen dioxide, sulphur dioxide, PM10 and PM2.5. The term "criteria air pollutants" derives from the requirement that the U.S. EPA must describe the characteristics and potential health and welfare effects of these pollutants.
CycloneAn air pollution control device that removes larger particles, generally greater than one micron from an air stream through centrifugal force.
DeforestationClearing Earth's forests on a massive scale, often resulting in damage to the quality of the land.
DioxinsFamily of 75 different toxic chlorinated hydrocarbon compounds formed as by-product in chemical reactions involving chlorine and hydrocarbons, usually at high temperatures. They are regarded as highly toxic compounds that are environmental pollutants and persistent organic pollutants (POPs).
DispersionThe movement of pollutants in the atmosphere is caused by transport, dispersion, and deposition. Dispersion results from local turbulence, that is, motions that last less than the time used to average the transport.
Dobson unitIt is the unit of measure for total ozone. If you were to take all the ozone in a column of air stretching from the surface of the earth to space, and bring all that ozone to standard temperature (0 °Celsius) and pressure (1013.25 millibars, or one atmosphere, or “atm”), the column would be about 0.3 centimeters thick. Thus, the total ozone would be 0.3 atm-cm. To make the units easier to work with, the “Dobson Unit” is defined to be 0.001 atm-cm. Our 0.3 atm-cm would be 300 DU.
DoseThe amount of a potentially harmful substance an individual ingests, inhales or absorbs through the skin.
DroughtDrought is an extended period when a region receives a deficiency in its water supply, whether atmospheric, surface or ground water. A drought can last for months or years. This condition occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm to the local economy.
DustConsists of particles in the atmosphere that come from various sources such as soil, dust lifted by weather (an aeolian process), volcanic eruptions, and pollution. Atmospheric or wind-borne dust, also known as aeolian dust, comes from arid and dry regions where high velocity winds are able to remove mostly silt-sized material, deflating susceptible surfaces. Ex: plant pollen, human and animal hairs, textile fibers, paper fibers etc.
EcosystemEcological system formed by the interaction of coacting organisms and their environment (a community of interdependent organisms together with the environment which they inhabit and with which they interact).
Electrostatic Precipitator (ESP)It is a highly efficient filtration device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit.
EmissionAny solid, liquid or gaseous substance coming out of any chimney, duct of flue or any other outlet
Emission capA mandated restraint, in a scheduled time-frame, that puts a “ceiling” on the total amount of anthropogenic greenhouse gas emissions that can be released into the atmosphere. The Kyoto Protocol mandates caps on the greenhouse gas emissions released by Annex-B countries/ Parties
Emission FactorFor stationary sources, the relationship between the amount of pollution produced and the amount of raw material processed or burned. For mobile sources, the relationship between the amount of pollution produced and the number of vehicle miles travelled. By using the emission factor of a pollutant and specific data regarding quantities of materials used by a given source, it is possible to compute emissions for the source. This approach is used in preparing an emissions inventory.
Emission InventoryAn estimate of the amount of pollutants emitted into the atmosphere from major mobile, stationary, area-wide and natural source categories over a specific period of time such as a day or a year.
Emission reduction unitThe emission reduction unit (ERU) is an emissions unit issued under a Joint Implementation project in terms of the Kyoto Protocol. An ERU represents a reduction of greenhouse gases under the Joint Implementation mechanism, where it represents one tonne of CO2 equivalent reduced.
Emission StandardThe maximum amount of a pollutant that is allowed to be discharged from a polluting source such as an automobile or smoke stack.
EmphysemaDamage to air sacs leading to loss of lung elasticity and acute shortness of breath.
EnvironmentThe sum of all physical, chemical, biotic and cultural factors that affect life of organism in any way.
Environmental indicatorsCharacteristics and factors for determining present and future conditions of the environment.
Environmental lawRules and controls of conduct in environmental/ natural resources affairs which are prescribed by or accepted by the governing authority of state and enforced by the government and the courts. Environmental law may derive from a Constitution, Legislative Acts, administrative rules, or common law. The body of law regulating or incidentally .affecting the relationships between humans and their environment.
Environmental managementVarious international, state and local measures and controls which are directed at environmental conservation, the rationale and sustainable allocation and utilisation of natural resources, the optimisation of interrelations between society and the environment, and the improvement of human welfare for present and future generations.
ExposureThe concentration of the pollutant in the air multiplied by the population exposed to that concentration over a specified time period.
Exposure AssessmentMeasurement or estimation of the magnitude, frequency, duration and route of exposure to a substance for the populations of interest.
Fine ParticlesFine particles are airborne particles which are smaller than coarse particles. They have an aerodynamic diameter of 2.5 µm or less (PM2.5). The fine particles which are smaller than 0.1 µm are referred to as ultrafine particles (PM0.1). Fine particles are largely formed from gases. Ultrafine particles are formed by nucleation, which is the initial stage in which gas becomes a particle. These particles can grow up to a size of 1µm either through condensation, when additional gas condensates on the particles, or through coagulation, when two or more particles combine to form a larger particle. Ultrafine particles (PM0.1) are part of the fine fraction (PM2.5).
FloodA flood is an overflow of water that submerges land which is usually dry. Flooding may occur as an overflow of water from water bodies (river or lake) or it may occur due to an accumulation of rainwater on saturated ground.
Fly ashFinely divided particles of ash in fuel gases resulting from combustion of fuel or other material.
FogIt is a collection of liquid water droplets or ice crystals suspended in the air at or near the Earth's surface. It reduces visibility to less than 1 kilometre (0.62 mi). It forms when the difference between air temperature and dew point is generally less than 2.5 °C or 4 °F.
Fossil FuelsProducts of partial or complete decomposition of plants and animals that occur as crude oil, coal, natural gas or heavy oils as a result of exposure to heat and pressure in the earth’s crust over millions of years.
Geographic Information System GISA system comprised of computer software and geographic data that enables analysis of those data and generation of maps.
Global Warming (GW)An increase in the temperature of the Earth's troposphere. Global warming has occurred in the past as a result of natural influences, but the term is most often used to refer to the warming predicted by computer models to occur as a result of increased emissions of greenhouse gases.
Global Warming Potential (GWP)The relative warming of a greenhouse gas over a specified period of time as compared to carbon dioxide (GWP of 1). GWP allows for the conversion of different greenhouse gas emissions into the same emissions unit, carbon dioxide equivalents (CO2E).
Green House Effect (GHE)Heating of air caused by allowing incoming solar radiation but inhibiting outgoing radiation. The warm air inside greenhouse causes its heating.
Green House Gases (GHGs)Greenhouse gases are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of infra-red radiation emitted by the earth’s surface, the atmosphere and clouds. This property causes the greenhouse effect. Six gases listed as GHGs in Kyoto Protocol are carbon dioxide, nitrous oxide, methane, hydroflurocarbons, perflurocarbons and sulphur hexachloride. Moreover, there are a number of entirely human made GHGs in the atmosphere such as the halocarbons and other chlorine and bromine containing substances, dealt with under the Montreal Protocol.
HalocarbonsHalocarbon compounds are chemicals in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms (fluorine, chlorine, bromine or iodine) resulting in the formation of organofluorine compounds, organochlorine compounds, organobromine compounds, and organoiodine compounds. Many synthetic organic compounds such as plastic polymers, and a few natural ones, contain halogen atoms; they are known as halogenated compounds or organohalogens.
Hazardous Air Pollutant (HAP)An air pollutant listed under section 112 (b) of the Federal Clean Air Act as particularly hazardous to health. Emission sources of hazardous air pollutants are identified by U.S. EPA and emission standards are set accordingly.
Haze (Hazy)A phenomenon that results in reduced visibility due to the scattering of light caused by aerosols. Haze is caused in large part by man-made air pollutants.
Health Risk Assessment (HRA)A document that identifies the risks and quantities of possible adverse health effects that may result from exposure to emissions of toxic air contaminants. A health risk assessment cannot predict specific health effects; it only describes the increased possibility of adverse health effects based on the best scientific information available.
HydrocarbonsCompounds containing various combinations of hydrogen and carbon atoms. They may be emitted into the air by natural sources (e.g., trees) and as a result of fossil and vegetative fuel combustion, fuel volatilization and solvent use. Hydrocarbons are a major contributor to smog.
Hydrochloroflurocarbon (HCFC)A chemical compound that would be a hydrocarbon except that one or more hydrogen atoms in each molecule is replaced by a chlorine atom and one or more hydrogen atom is replaced by a fluorine atom. Some HCFCs are implicated in the destruction of stratospheric ozone.
IncinerationIncineration of waste materials converts the waste into ash, flue gas, and heat. The ash is mostly formed by the inorganic constituents of the waste, and may take the form of solid lumps or particulates carried by the flue gas.
Inert Gasgas that does not react with the substances coming in contact with it.
Intergovernmental Panel on Climate Change (IPCC)A scientific intergovernmental body set up by the World Meteorological Organization (WMO) and by the United Nations Environment Programme (UNEP) to provide the decision-makers and others interested in climate change with an objective source of information about climate change.
InversionA layer of warm air in the atmosphere that prevents the rise of cooling air and traps pollutants beneath it.
Ionising RadiationIonizing radiation is radiation that carries enough energy to liberate electrons from atoms or molecules, thereby ionizing them. Ionizing radiation is composed of energetic subatomic particles, ions or atoms moving at relativistic speeds, and electromagnetic waves on the high-energy end of the electromagnetic spectrum. Gamma rays, X-rays, and the higher ultraviolet part of the electromagnetic spectrum are ionizing, whereas the lower ultraviolet, visible light, infrared, microwaves, and radio waves are considered non-ionizing radiation.
IonosphereLayer of uppermost atmosphere extending upwards from about 80km above the surface upto 300km, in which atoms tend to be ionised by incoming solar radiation.
IPCCThe Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. In the same year, the UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC. The IPCC is a scientific body under the auspices of the United Nations (UN). It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate related data or parameters.
Kyoto Global Warming PactCame into force in 2005, imposing limits on emissions of Carbon dioxide and other GHGs.
Kyoto ProtocolIs a treaty negotiated in Kyoto, Japan in 1997 between 159 countries setting out legally binding reduction targets for six greenhouse gases (GHG). This protocol requires countries to take appropriate measures to reduce their overall GHG emissions to a level at least 5% below the 1990 level by the commitment period 2008-2012.
Lapse rateIt is defined as the rate at which atmospheric temperature decreases with increase in altitude.
Lifetime (in the atmosphere)The approximate amount of time it would take for the anthropogenic increment to an atmospheric pollutant concentration to return to its natural level (assuming emissions cease) as a result of either being converted to another chemical compound or being taken out of the atmosphere via a sink.
London SmogA contraction of fog and smoke that characterized air pollution episodes in London. Fog, with chemical and physical pollutants, remained there for four days in 1952 and 5 days in 1962. In 1952, 4000 people died while in 1962 about 700 died.
MesopauseIt is the temperature minimum at the boundary between the mesosphere and the thermosphere atmospheric regions.
MesosphereA Layer of atmosphere between the stratosphere and thermosphere (50-85 km above the earth’s surface). This region is situated between the stratopause and the mesopause, in which the temperature generally decreases with height.
MistLiquid (water) droplets smaller the 10 micron in diameter suspended in the atmosphere reducing visibility to between 1 and 2 km.
MitigationThe action of reducing the severity, seriousness, or painfulness of something.
Mixing HeightIt is the height to which the lower atmosphere will undergo mechanical or turbulent mixing, producing a nearly homogeneous air mass.
MonitoringTo measure quantitatively or qualitatively the level of a substance over a period of time. The periodic or continuous sampling and analysis of air pollutants in ambient air or from individual pollution sources.
Montreal ProtocolThe Montreal Protocol on Substances that Deplete the Ozone Layer (a protocol to the Vienna Convention for the Protection of the Ozone Layer) is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion.
MutagenicThe ability of a chemical or physical agent to produce heritable changes in the DNA of living cells.
MutationsThe changing of the structure of a gene, resulting in a variant form which may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.
National Ambient Air Quality Standards (NAAQS)An air quality standard set by the US EPA as required by the Clean Air Act. The primary standard for a pollutant is the maximum concentration of that pollutant (over a specified averaging period) that should be observed within a community for the protection of human health. The secondary standard is designed to protect the community welfare.
Natural resourcesA feature or component of the natural environment that is of value in serving human needs (ex: soil, water, plant life, wildlife etc.). Some natural resources have an economic value (ex: timber) while others have uneconomic value (ex: scenic beauty).
NauseaAn unpleasant sensation with a tendency to vomit.
NecrosisIt is a form of cell injury that results in the premature death of cells in living tissues by autolysis.
Non renewable resourcesResources not capable of perpetuating themselves (ex: coal, oil and minerals). Resource that exists in a fixed amount (stock) in various places in the earth’s crust and has potential for renewal only by geological, physical and chemical processes taking place over hundreds of millions of years. These are exhaustible because we are extracting and using them at a much faster rate than they were formed.
Non-Point SourcesDiffuse pollution sources that are not recognized to have a single point of origin.
Noxious gasesare very harmful, poisonous, or very unpleasant.
OxidantsAlso known as oxidizing agent, oxidizer or oxidiser, is the element or compound in an oxidation-reduction (redox) reaction that accepts an electron from another species. Because the oxidizing agent is gaining electrons (and is thus often called an electron acceptor), it is said to have been reduced.
OzoneA colourless gas, a highly reactive compound in which each molecule consists of three oxygen atoms. Ozone is "good up high, bad nearby": In the stratosphere, it forms a protective layer against UV light. But at ground level it is increasingly harmful to breathe as concentrations rise and contributes to or aggravates various heart and lung conditions, such as asthma and it also interferes with the ability of plants (including crops) to produce and store food. Ozone is a criteria pollutant and is the prime ingredient of summertime smog in most cities. Ozone is not emitted directly into the air, but is formed in reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of heat and sunlight.
Ozone depleting substancesOzone depleting substances (ODSs) are those substances which deplete the ozone layer and are widely used in refrigerators, air conditioners, fire extinguishers, in dry cleaning, as solvents for cleaning, electronic equipment and as agricultural fumigants. Ex: Chlorofluorocarbons (CFCs), Halon, Carbon tetrachloride (CCl4), Methyl chloroform (CH3CCl3), Methyl bromide (CH3Br) etc.
Ozone holeThinning break in the stratospheric ozone layer. Designation of “ozone hole” is made when detected amount of depletion exceeds fifty percent. Seasonal ozone holes have been observed over both the Antarctica and the Arctic region and part of Canada and the extreme North-eastern United States.
Ozone Layer (Ozonosphere)A layer of ozone in the lower portion of the stratosphere, 12 to 15 miles above the Earth's surface, which helps to filter out harmful ultraviolet rays from the sun.
Peroxyacetyl Nitrate (PAN)A group of compounds formed from the photochemical reactions of nitrogen and organic compounds. PANs are components of smog and known to cause eye irritation.
PersistenceRefers to the length of time a compound stays in the atmosphere, once introduced. A compound may persist for less than a second or indefinitely.
Persistent Organic Pollutants (POPs)They are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulate in human and animal tissue, bioaccumulate in food chains, and to have potential significant impacts on human health and the environment.
Photochemical ReactionA term referring to chemical reactions brought about by the light energy of the sun. The reaction of nitrogen oxides with hydrocarbons in the presence of sunlight to form ozone is an example of a photochemical reaction.
Photochemical SmogComplex mixture of air pollutants (oxidants) produced in the atmosphere by the reaction of hydrocarbons and nitrogen oxides under the influence of sunlight. Three of the most harmful photochemical oxidants are ozone (O3), peroxyacetyl nitrate (PAN) and various aldehydes.
PhotolysisChemical decomposition induced by light or other energy.
PlumeA visible or measurable discharge of a contaminant from a given point of origin that can be measured according to the Ringelmann scale.
PM 2.5 (Particulate Matter)Tiny particles with an aerodynamic diameter less than or equal to a nominal 2.5 microns. This fraction of particulate matter penetrates most deeply into the lungs.
PM10A criteria air pollutant consisting of small particles with an aerodynamic diameter less than or equal to a nominal 10 microns (about 1/7 the diameter of a single human hair). Their small size allows them to make their way to the air sacs deep within the lungs where they may be deposited and result in adverse health effects. It also causes visibility reduction .
Point sourceA single identifiable source that discharges pollutants into the atmosphere. Ex: Smokestack of power plant, chimney of a house etc.
PoisoningPoisoning occurs when any substance interferes with normal body functions after it is swallowed, inhaled, injected, or absorbed.
Pollutant Standards Index (PSI)A numerical index formerly used for reporting severity of air pollution levels to the general public. The PSI incorporated the five criteria pollutants -- ozone, PM10, carbon monoxide, sulphur dioxide and nitrogen dioxide -- into one single index. The higher the index, the higher the level of pollutant and the greater likelihood of health effects.
PollutionAddition of some exogenous substances in the environment which are harmful for organisms including human beings.
Pollution cleanupDevices or process that removes or reduces the level of a pollutant after it has been produced or has entered the environment. Ex: Automobile emission control devices.
Pollution preventionDevice, practices or processes that prevent a potential pollutant from forming or from entering the environment or that sharply reduces or minimizes the amounts entering the environment.
Polychlorinated biphenyls (PCBs)Group of 209 different toxic, oily, synthetic chlorinated hydrocarbon compounds that can be biologically amplified in food chains and webs.
Polycyclic Aromatic Hydrocarbons (PAHs)Organic compounds which include only carbon and hydrogen with a fused ring structure containing at least two benzene (six-sided) rings. PAHs may also contain additional fused rings that are not six-sided. The combustion of organic substances is a common source of atmospheric PAHs.
PopulationGroup of individual organisms of the same species living within a particular area
Population densityNumber of organisms in a particular population found in a specified area.
Power plantsA power plant (also referred to as a generating station, power plant, powerhouse or generating plant) is an industrial facility for the generation of electric power. Each power station contains one or more generators, a rotating machine that converts mechanical power into electrical power by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely. Most power stations in the world burn fossil fuels such as coal, oil, and natural gas to generate electricity, and some use nuclear power, but there is an increasing use of cleaner renewable sources such as solar, wind, wave and hydroelectric.
PrecipitationWater in the form of rain, sleet, hail and snow that falls from the atmosphere onto the land and bodies of water.
Primary pollutantChemical that has been added directly to the air by natural events or human activities and occurs in a harmful concentration.
Radiative forcingRadiative Forcing (RF) is the measurement of the capacity of a gas or other forcing agents to affect that energy balance, thereby contributing to climate change. RF generally expresses the change in energy in the atmosphere due to GHG emissions.
RadonA colourless, naturally occurring, radioactive, inert gaseous element formed by radioactive decay of radium atoms in soil or rocks. It is a major source of indoor air pollution
Relative humidityMeasure (as a percentage) of the amount of water vapour in a certain mass of air compared with the maximum amount it could hold at that temperature.
Remote SensingRemote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object. It is the scanning of the earth by satellite or high-flying aircraft in order to obtain information about it.
Ringelmann ChartA series of charts, numbered 0 to 5, that simulate various smoke densities by presenting different percentages of black. A Ringelmann No. 1 is equivalent to 20 percent black; a Ringelmann No. 5 is 100 percent black. They are used for measuring the opacity or equivalent obscuration of smoke arising from stacks and other sources by matching the actual effluent with the various numbers, or densities, indicated by the charts.
Risk AssessmentAn evaluation of risk which estimates the relationship between exposure to a harmful substance and the likelihood that harm will result from that exposure.
Risk ManagementAn evaluation of the need for and feasibility of reducing risk. It includes consideration of magnitude of risk, available control technologies and economic feasibility.
ScrubbersThese are a diverse group of air pollution control devices that uses a high energy liquid spray to remove some particulates and/or gases from industrial exhaust streams. The gases are removed either by absorption or chemical reaction.
Secondary pollutantA pollutant formed by the combination of other (primary) pollutants in the environment. Ex: Ground level Ozone is the best example of secondary pollutant which is formed by interaction between NOx and VOC.
SmogA term coined by H. A. Des Voeux, to denote combination of smoke and natural fog which in urban areas, may have unpleasant and even disastrous consequences. Ex: London Smog. The word is also applied to other air pollution effect not necessarily connected with smoke such as ‘Los Angeles Smog’ which arises from nitrogen oxides and hydrocarbons emitted by motor vehicles and the photochemical action of sunlight.
SmokeA form of air pollution consisting primarily of particulate matter (i.e., particles released by combustion). Other components of smoke include gaseous air pollutants such as hydrocarbons, oxides of nitrogen and carbon monoxide. Sources of smoke may include fossil fuel combustion, agricultural burning and other combustion processes.
Sootfine carbon particles that have a black appearance when emitted into the air.
StratosphereLayer of the atmosphere lies between 12 and 50 km above the earth’s surface in which temperature increases with altitude.
Sulphur dioxide (SO2)A constituent of products of combustion of a wide variety of fuels, but particularly heavy fuel oil and coal. It is also released in volcanic eruptions.
Sustainable developmentDevelopment and or growth that meets the needs of the present generation without compromising the ability of future generations to meet their own needs.
TemperatureThe degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.
Thermal Power PlantsA thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator.
Thermosphereof upper atmosphere in which temperature increases with height.
ThresholdThe magnitude or intensity that must be exceeded for a certain reaction, phenomenon, result, or condition to occur or be manifested.
Total Organic Gases (TOG)Gaseous organic compounds, including reactive organic gases and the relatively un-reactive organic gases such as methane.
Total Suspended Particulate (TSP)Particles of solid or liquid matter -- such as soot, dust, aerosols, fumes and mist, up to approximately 30 microns in size.
Toxic Air Contaminant (TAC)An air pollutant, which may cause or contribute to an increase in deaths or in serious illness, or which may pose a present or potential hazard to human health.
Toxic substancesChemical or physical agents that produce adverse responses in the biological systems with which they interact. The responses may be sudden and short span (acute toxicity) or long term constant or continuous (chronic toxicity).
Trace elementIt is a dietary mineral that is needed in very minute quantities for the proper growth, development, and physiology of the organism.
TroposphereThe lower part of the terrestrial atmosphere, extending from the surface up to a height varying from 9 km at the poles to about 17 km at the equator, in which temperature decreases fairly regularly with height.
Ultraviolet radiationUltraviolet (UV) light is electromagnetic radiation with a wavelength from 400 nm to 10 nm, shorter than that of visible light but longer than X-rays. In humans, excessive exposure to all bands of UV radiation can result in chronic harmful effects on the skin, eye, and immune system.
UNCEDThe United Nations Conference on Environment and Development (UNCED), also known as the Rio Summit, Rio Conference, and Earth was a major United Nations conference held in Rio de Janeiro from 3 to 14 June 1992. The issues addressed included: systematic scrutiny of patterns of production of toxic components, such as lead in gasoline, or poisonous waste including radioactive chemicals, alternative sources of energy to replace the use of fossil fuels which are linked to global climate change, new reliance on public transportation systems in order to reduce vehicle emissions, congestion in cities and the health problems caused by polluted air and smoke and the growing scarcity of water. An important achievement was an agreement on the Climate Change Convention which in turn led to the Kyoto Protocol.
UNDPThe United Nations Development Programme (UNDP) is the United Nations' global development network with headquartered in New York City. UNDP advocates for change and connects countries to knowledge, experience and resources to help people build a better life. It provides expert advice, training, and grant support to developing countries, with increasing emphasis on assistance to the least developed countries.
UNEPUNEP, established in 1972, is the voice for the environment within the United Nations system. UNEP acts as a catalyst, advocate, educator and facilitator to promote the wise use and sustainable development of the global environment. Its work encompasses, Assessing global, regional and national environmental conditions and trends, developing international and national environmental instruments, strengthening institutions for the wise management of the environment.
UNFCCCThe United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty (currently the only international climate policy venue with broad legitimacy, due in part to its virtually universal membership) negotiated at the United Nations Conference on Environment and Development (UNCED), informally known as the Earth Summit, held in Rio de Janeiro from 3 to 14 June 1992. The objective of the treaty is to "stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.
UrbanizationIt is a population shift from rural to urban areas, and the ways in which society adapts to the change. It predominantly results in the physical growth of urban areas, be it horizontal or vertical.
USEPAThe United States Environmental Protection Agency (EPA or sometimes USEPA) is an agency of the U.S. federal government which was created for the purpose of protecting human health and the environment by writing and enforcing regulations based on laws passed by Congress.
VapourThe gaseous phase of liquids or solids at atmospheric temperature and pressure.
VentilationIn this guide, the movement of air between the inside and outside of a building usually through windows, doors and air vents built into the building’s walls or ceilings.
VisibilityA measurement of the ability to see and identify objects at different distances. Visibility reduction from air pollution is often due to the presence of sulphur and nitrogen oxides, as well as particulate matter.
Visibility Reducing Particles (VRP)Any particles in the atmosphere that obstruct the range of visibility.
VolatileAny substance that evaporates readily.
Volatile Organic Compounds (VOCs)Carbon-containing compounds that evaporate into the air (with a few exceptions). VOCs contribute to the formation of smog and/ or may themselves be toxic. VOCs often have an odour and some examples include gasoline, alcohol and the solvents used in paints
VolcanoA volcano is a rupture on the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption but also other areas such as volcanic ash which can spread over long distances.
WeatherThe state of the atmosphere at a given time, as defined by the various meteorological parameters.
WheezingBreathe with a high pitched whistling or rattling sound in the chest, as a result of obstruction in the air passages.
Wind directionWind direction is the direction from which it originates. For example, a northerly wind blows from the north to the south. Wind direction is usually reported in cardinal directions or in azimuth degrees
Wind roseA wind rose is a circular display of how wind speed and direction are distributed at a given location for a certain time period.
World BankThe World Bank is a United Nations international financial institution that provides loans to developing countries for capital programs. The World Bank is a component of the World Bank Group, and a member of the United Nations Development Group.
World Health Organization (WHO)It is a specialized agency of the United Nations (UN) that is concerned with international public health. It was established on 7 April 1948, headquartered in Geneva, Switzerland.
World Resource Institute (WRI)It is a non-governmental global research organization which seeks to create equity and prosperity through sustainable natural resource management. The efforts of the WRI are focused on six key areas—climate, clean energy, food, forests, water, and cities and transportation.
XenobioticIt is a foreign chemical substance found within an organism that is not normally naturally produced by or expected to be present within that organism. It can also cover substances which are present in much higher concentrations than are usual.
Zero Emission Vehicle (ZEV)Vehicles which produce no emissions from the on-board source of power (e.g., an electric vehicle).
Zero emissionsAn engine, motor or other energy source that does not produce any gas or release any harmful gases directly into the environment.