A Decision Support System for Indian Urban Air Quality Management


Activity data
A quantitative measurement of an activity that results in emission of a pollutant during a period of time.
American Meteorological Society/Environmental Protection Agency Regulatory Model.
Air pollution
Toxic or radioactive gases or particulate matter introduced into the atmosphere, usually as a result of human activity.
Air Quality Index (AQI)
A numerical index used for reporting quality of air and severity pollution levels to the public. AQI incorporates five criteria pollutants - ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide - into a single index.AQI also incorporates the 8-hour ozone standard and the 24-hour PM2.5 standard into the index calculation.
Air Quality Monitoring
The sampling and measuring of ambient (outdoor) air pollutant concentrations.
Ambient Air
Any unconfined portion of the atmosphere, open air or surrounding air.
Area Source
Any source of air pollution that is released over a relatively small area, which cannot be classified as a point source. Such sources may include small businesses areas and household activities.
Incombustible residue left over after burning process or thermal processes.
Background location
Monitoring site away from all the sources and in upwind direction.
Carbon dioxide (CO₂)
A colorless, odorless gas that occurs naturally in the Earth's atmosphere.
Carbon monoxide (CO)
A colorless, odorless, poisonous gas, produced by combustion of fossil fuel, including gasoline, oil and wood.
Chemical Mass Balance
Air quality receptor model that has been applied to air quality problems & air resources management. CMB models combine the chemical and physical characteristics of gases and particles measured at the sources and measurement sites (receptors) both, to identify the presence and to quantify source contributions to measured concentrations at receptor.
Clean fuels
Low-pollution fuels that can replace ordinary gasoline. These are alternative fuels, including gasoline-alcohol mixtures, natural gas, and LPG.
Burning of any substance. Many pollutants, such as sulfur dioxide, nitrogen oxides, and particulates are combustion products, mainly emitted from burning of fuels such as coal, oil, gas, and wood.
The relative amount of a substance mixed with another substance.
Control scenario
Process of identifying and estimating natural and anthropogenic sources of emissions. Finalizing the major factors that are likely to influence future emissions from these sources and defining various sets of assumptions about how these factors may change in the future and estimating the impact of these changes on emissions.
Criteria Air Pollutants
Carbon monoxide, ozone, sulfur dioxide, nitrogen dioxide, particulate matter. Basically the pollutants for which there are NAAQS.
The movement of a pollutant from a high concentration to lower concentrations covering a larger area.
Dispersion Modeling
A model using mathematical equations and algorithms with meteorological and emissions inventory data, to simulate how air pollutants are dispersed. Used to predict the downwind concentration of air pollutants emitted from different sources.
Solid particulate matter that can become airborne.
Release of pollutants into the air from a source.
Emission (Anthropogenic)
Emissions from man-made activities.
Emission Factor
A measure of an average rate of emission of a pollutant for a defined activity rate.
Emissions Inventory (EI)

The calculation of total air emissions based on activity levels and emission factors. EI is generally expressed in kilograms per day or tons per year.

Baseline EI - Emission Inventory of the present year for which source activity data have been collected and analyzed.

BAU Scenario EI - Emission inventory for the future years with growth rates applied to baseline source activities.

Controlled Scenario EI - Emission inventory for the future years with control measures applied to BAU source activities.

A measured level of an air pollutant higher than proposed standard ambient air quality.
The concentration of the pollutant in the air multiplied by the population exposed to that concentration over a specified time period.
Fossil fuels

Fuels such as coal, oil, and natural gas.

Fugitive dust

Dust particles released in the air through activities like soil cultivation or dirt roadways.

Fugitive emissions

Emissions not measured due to equipment leaks, evaporative processes, and windblown disturbances.


Petroleum fuel, used in cars, trucks, etc.

Growth Rate

Annual growth rate (%) for any particular source


Compounds containing various combinations of hydrogen and carbon atoms.

ISC Model

Industrial Source Complex (ISC), model is a popular steady-state Gaussian plume model, widely used to assess pollutant concentrations from different sources.

Kerbside location

Edge of a busy road, where public exposure is expected to be short term.

Line source

A one-dimensional source of air pollutant emissions, such as the emissions from the vehicular traffic on road.

Mass closure

Mass closure refers to a simple mass balance procedure that can be used for apportioning particulate matter to its component.


A metadata record is a file of information, which captures the basic characteristics of a data or information resource. Metadata have been used in various forms as a means of cataloging archived information.

microgram (µg)

One millionth of a gram: 1 µg = 10-6 g = 0.001 mg.

micrograms per cubic meter (µg/m³)

The mass in micrograms of a substance contained within a cubic meter of substance or vacuum.


Mathematical tools used to calculate atmospheric pollution.

National ambient air quality standards (NAAQS)

Ambient standards developed that must be attained and maintained to protect public health.

Nitrogen oxides (NOx)

Nitrogen oxides are produced from burning fuels, including gasoline and coal.

Organic compounds

A large group of chemical compounds containing mainly carbon, hydrogen, nitrogen, and oxygen.


A gas which is a form of oxygen. Ozone consists of three oxygen atoms combine together an ozone molecule.

Particulate matter (PM-10)

Particulate matter is a criteria air pollutant and is a particle with diameter of 10 micrometers or less. Particulate matter includes dust, soot and other tiny bits of solid materials that are released into the air.

Particulate matter (PM-2.5)

Includes tiny particles with diameter less than or equal to 2.5 microns. This fraction of particulate matter penetrates most deeply into the lungs.

Point Source

A stationary location or fixed facility from which pollutants are discharged.

Pollutants (pollution)

Unwanted chemicals or other materials found in the air which can harm health and environment. Many air pollutants occur as gases or vapors, but some are very tiny solid particles: dust, smoke, or soot.

Quality assurance/quality control (QA/QC)

A system of procedures, checks, audits, and corrective actions to ensure that all research design and performance, environmental monitoring and sampling achieve desired data quality

Receptor Modeling

Receptor models use the chemical and physical characteristics of gases and particles measured at source and receptor to identify and quantify source contributions to concentrations at receptor.


A scenario is the description of a possible, consistent future form or development.

Secondary particulate

Particles that usually form over several hours or days and attain diameters between 0.1 and 1 µm.


Any place or object from which pollutants are released.

Source Apportionment

The identification and estimation of the relative contribution from different sources to the total emission (pollution) at any location/site

Source profile

A source profile is the chemical composition of the emissions, with each chemical species expressed as a mass fraction of the total.

Stationary source

A place or object from which pollutants are released which stays in place. Stationary sources include power plants, gas stations and houses.

Sulfur dioxide

Sulfur dioxide is a gas produced by burning coal.

Total suspended particulates

Particles of solid and liquid matter suspended in air. Particle sizes represented by the method are up to 100 µm in diameter.


A vintage of vehicle is usually defined as a year or span of years in which that model is produced.

Volatile organic compounds (VOCs)

Organic chemicals all contain the element carbon (C). Volatile organic chemicals include gasoline and chemicals such as benzene, toluene, xylene, etc. Many are hazardous air pollutants, such as benzene.

Wind Rose

A graphic tool used by meteorologists to summarizes information about the wind at a particular location over a period of time. It gives a view of how wind speed and direction are typically distributed and radiating lines shows the frequency and strength of winds respective to the location.


AQ - Air Quality
ARAI - Automotive Research Association of India
BAU - Business as Usual
BC - Black Carbon
CDAC - Centre for Development of Advanced Computing
CH₄ - Methane
CMB - Chemical Mass Balance
CO - Carbon Monoxide
CO₂ - Carbon Dioxide
CPCB - Central Pollution Control Board
CV - Coefficient of Variation
EC - Elemental Carbon
EF - Emission Factor
EI - Emission Inventory
GIS - Geographic Information System
HC - Hydrocarbon
ISC - Industrial Source Complex
N₂O - Nitrous Oxide
NEERI - National Environmental Engineering Research Institute
NH₃ - Ammonia
NO - Nitric Oxide or Nitrogen Monoxide
NO₂ - Nitrogen Dioxide
NOx - Oxides of Nitrogen
OC - Organic Carbon
OM - Organic Matter
PAHs - Polycyclic Aromatic Hydrocarbons
PM - Particulate Matter
PM10 - Fine Particulates, size 10 µm or less
PM2.5 - Ultra-Fine Particulates, size 2.5 µm or less
QA/QC - Quality Assurance and Quality Control
SD - Standard Deviation
SO₂ - Sulphur Dioxide
SPCB - State Pollution Control Board
TC - Total Carbon
TERI - The Energy and Resources Institute
TSP - Total Suspended Particulates
USEPA - United States Environmental Protection Agency
VOCs - Volatile Organic Compounds