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Introduction
Air pollution worldwide is a growing threat to human health and the natural environment
Air pollution may be described as contamination of the atmosphere by gaseous, liquid, or solid wastes or by-products that can endanger life, attack materials and reduce visibility
Some of the questions which might come to mind while thinking about pollution are:
Are we doing something about solving these problems? Do we know enough about the conditions under which a
pollution episode occurs? What are the regulations? How to control emissions?
Sources Of Air Pollutants
Natural Sources Volcanoes Coniferous forests Forest fires Pollens Spores Dust storms Hot springs
Man-made Sources Fuel combustion - Largest contributor Chemical plants Motor vehicles Power and heat generators Waste disposal sites Operation of internal-combustion engines
Ambient Air
The air all around us
Should We Worry About Air Pollution ?
Air pollution affects every one of us
Air pollution can cause health problems and in an extreme case
even death
Air pollution reduces crop yields and affects animal life
Air pollution can soil and corrode materials, and monuments
Air pollution can cause significant economic losses
Accidents and Episodes
1930 -3 day fog in Meuse Valley, Belgium 1931 -9 day fog in Manchester, England 1948 -Plant emissions in Donora, Penn, USA 1952 -4 day fog in London 1970 -Radionuclide emissions, Three Mile Island, USA 1984 -Release of Methyl isocynate in Bhopal, India
1986 -Radionuclide releases, Chernobyl, Ukraine
Air Quality• Indoor
Radon Combustion by-products
CO, CO2, SO2, Formaldehyde, Hydrocarbons, NOx, Particulates, Polyaromatic hydrocarbons
Environmental Tobacco Smoke (ETS) Volatile organic compounds Formaldehyde Biological contaminants Pesticides
• Outdoor SO2 CO, CO2 NO2 Ozone TSP Pb Toxic pollutants
Definition of an Air Pollutant
A contaminant that affects human life, plant life, animal life and property or a contaminant which interferes with the enjoyment of life and property is an air pollutant
Ohio EPA provides a definition of "Air pollutant" or"air contaminant “as particulate matter, dust, fumes, gas, mist, smoke, vapor, or odorous substances.
How to define an air pollutant ? Basis: Chemicals present in the environment Process:
Use composition of the clean air used as a bench mark.
When the concentration of a chemical is above the concentration of the chemical present in air, it is termed as an air pollutant
Physical Forms of Air Pollutants
Gaseous form Sulfur dioxide Ozone Hydro-carbon vapors
Particulate form Smoke Dust Fly ash Mists
Classification of Pollutants
Primary pollutants: remain in the same chemical form, as they are
released from a source directly into the atmosphere. Sulfur dioxide Hydrocarbons
Secondary pollutants: are a result of chemical reaction among two
or more pollutants. PAN
Common Air Pollutants
Sulfur Dioxide Hydrocarbons Ozone Total Suspended Particulate Matter/Fine Particulates Nitrogen Oxides Carbon Monoxide Lead Carbon Dioxide
Toxic Air Pollutants
Toxic air pollutants may originate from natural sources as well as
from manmade sources such as stationary and mobile sources
The stationary sources like factories and refineries serve as major
contributors to air pollution
The Clean Air Act of 1990 provides a list of 189 chemicals to be
regulated under the hazardous air pollutant provisions of the act
(See EPA site for current list chemicals)
Source Classification
Sources may be classified as:
(A) Primary Secondary
(B) Combustion Non-combustion
(C) Stationary Mobile
(D) Point:These sources include facilities that emit sufficient amounts of pollutants worth listing Area: all other point sources that individually emit a small amount of pollutants are considered as area sources Natural (biogenic)
Source Classification
(E) Classification for reporting air emissions to the public:
Transportation sources: Includes emissions from transportation sources during the combustion
process Stationary combustion sources: These sources produce only energy and the emission is a result of fuel combustion Industrial sources: These sources emit pollutants during the manufacturing of products Solid waste Disposal:Includes facilities that dispose off
unwanted trash Miscellaneous: sources that do no fit in any of the above c
categories like forest fires, coal mining etc.
Air Pollution Index
Air pollution indices were introduced to translate technical information on concentration levels of various pollutants into a simple and easy to understand language for the public
The U.S.E.P.A has developed the pollutant standard index (PSI) for introducing consistency in providing information regarding the air quality throughout the U.S. The system is based on a scale of 0-500
Index Value is assigned based on the amount of air pollutants in the air and associated health effect
Development of an Emission Inventory
Emission Inventory is a study of the pollutant emissions from sources in a given area
Emission Inventories have been developed by: plant local environmental agency national environmental agency
Details for development of an emission inventory depend on: area of coverage nature of sources purpose
Well known emission inventories in US Inventory of criteria pollutants Toxic release inventory (TRI)
Steps to Develop Emission Inventory
Steps Involved in development of an emission inventory are:
Planning
Data Collection
Data Analysis
Reporting Data
Planning
Defines scope and purpose of inventory
Major points considered during this step are: Pollutants to be enlisted in the inventory are specified along
with the methods to collect or estimate data Use of data and geographical area involved are determined Legal authority and responsibility of specific groups to acquire
data is considered along with an assessment of cost and
resources
Data Collection
Steps to be taken:
Emissions are classified Pollutant sources are located and classified Quality and quantity of materials handled, processed, or
burned is determined
Collection Methods: During this stage data may be collected by
Mail survey Plant inspection Field surveys
Data from literature:
Industrial files Government files Periodicals Trade journals Scientific publications
Information Collected during Data Collection
General source information - location, ownership, and nature of
business Activity levels - amount of fuel and materials (input) Amount of production - output of the plant Control device information - type of pollution control devices Information required to estimate emissions - temperature, tank
conditions, hours of operations, seasonal variation and other data
Data Analysis
Check accuracy Calculation of emission rate is done using:
Monitoring data (most accurate & most expensive) Emission factors from AP-42 , Mass balance, and Engineering calculation
Emission Rate
Emission rate is the weight of a pollutant emitted per unit time.
Emission factor is an estimate of the rate at which a pollutant is released into the atmosphere per unit level of activity
To calculate emission rate: EMISSION RATE = [INPUT] x [EMISSION FACTOR] x [APLICABLE CORRECTION FACTORS] x [HOURS OF OPERATION] x [SEASONAL VARIATION]
Reporting Data
Information can be filed with the following pollution control
agencies: Local Regional National
In US, data gathered by state agencies are reported to the USEPA Emission data are available from the USEPA’s web site
Uses of an Emission Inventory
The Emission Inventory developed may be used for: Identifying types of pollutants emitted from specific sources. Determining the magnitude or amount of emissions from those
sources Developing the emissions distribution in time and space Calculating emission rates under specific plant operating
conditions Finding out the relation of ambient air pollutant concentration with
specific sources Input data for air quality modeling and risk Determine pollution control options for public health Estimating cost based on emissions
Air Pollution in Asia
Asia represents a major source of air pollution as a result of rapid population growth, explosive industrialization, and few environmental regulations
China:China is polluted with sulfur dioxide (15 million tons) and particulate matter (20 million tons) because of the use of the high sulfur coal used to generate energy.
Other Chemicals:1. Carbon Dioxide from Industry 2. Greenhouse Gases from Industry 3. Nitrogen Oxides from Cars 4. Acid Rain
With all these problems China has very little air pollution control.
Air Pollution in Asia
India: Most common air pollutant: suspended particulate matter is due to
use of coal in power plants Use of low quality coal produces 45 million metric tons of ash
annually When particulate matter ash is mixed with auto exhaust the emissions
across limits resulting in an increase in respiratory diseases and allergies
South Korea: SO2 is the major pollutant in South Korea, however, it is being
controlled by using air pollution control equipment
Hong Kong: Vehicular emissions contribute to air pollution problems with diesel
powered engines being the prime culprit.
ppm and µg/m3 relationship
Convert From To Multiply bymicrograms/m3 PPM (vol) 0.02404/M
micrograms/m3 PPM (wt) 0.000835
PPM (vol) micrograms/m3 M/0.02404
PPM (wt) micrograms/m3 0.001198
where M is the molecular weight of the pollutant gas.