1. Introduction

2. Introduction
Air pollution may be described as contamination of the atmosphere by gaseous, liquid, solid wastes or by-products that can endanger life, attack materials and reduce visibility.
Air pollution worldwide is a threat to human health and the natural environment.
It may also be defined as the presence of matter in atmosphere at concentrations, durations, and frequencies that adversely affect human health and environment.

3. Introduction
Air pollution can be caused due to the burning of wood, coal, oil, petrol, or by spraying pesticides.
Some of the questions which might come to  mind while thinking about air 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?

4. 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 damage monuments.
Air pollution can cause significant economic losses.
In short, air pollution does not only damage air; it also damages environment on earth’s surface and their inhabitants.

5. History of Air Pollution in the US
The problems of air pollution in Los Angles, New York city, and Chicago during the fifties drew attention of regulators in the United States.
Conventional pollutants due to auto emissions and smoke stacks were the major thrusts of air pollution during the sixties and seventies.
Invisible emissions of toxic pollutants were recognized in the late seventies.
In early eighties scientists observed a slow down in growth of red spruce in the mountain areas of north-eastern US as a result of acid rain.
In early nineties standards for ozone air pollution and sulfur dioxide has been revised
In late nineties standard for particulate matter pollution was strengthened.

6. History of Air Pollution in the US
In 2000, EPA passed a new rule for diesel, capping sulfur levels in diesel fuel at 15 parts per million by 2007.
In 2005, EPA issued the Clean Air Interstate Rule (CAIR), to achieve the largest reduction in SO2 & NOX from the atmosphere in the eastern United States.
In 2006, EPA issued the strongest National Air Quality Standards for particle pollution in the country’s history.
In 2010 (January 6th), EPA has proposed to strengthen the National Ambient Air Quality Standards for ground-level ozone.

7. Air Quality Standards Achievement

8. Accidents and Episodes
1930 -3 day fog in Meuse Valley, Belgium
day fog in Manchester, England
1948 -Plant emissions in Donora, Penn, US
1952 -4 day fog in London, England
1970 -Radionuclide emissions, Three Mile Island, US
1984 -Release of Methyl isocynate in Bhopal, India
1986 -Radionuclide releases, Chernobyl, Ukraine 
1997 – Haze disaster in Indonesia
2001 – Wildfires in Sierra Nevada, US
2001 – Enormous clouds of dust in New York during Collapse of World Trade Center, US
2002 – Violent dust storm in Queensland, Australia
Jilin chemical plant explosions, Jilin city, China
2007 – Wildfires in TALLAHASSEE Florida, US
Kingston Fossil Plant coal fly ash slurry spill, Kingston, US

9. Eras of Air Pollution Pre-Industrial Era Early-Industrial Era
Early 20th Century
Late 20th Century
Early 21st Century

10. Air Pollutant
Contaminant that affects human life, plant life, animal life and property could be termed as an air pollutant.
Air pollutants are classified into two categories:
Primary pollutants: These pollutants are emitted from a source directly into the atmosphere.
e.g. Sulfur dioxide and Hydrocarbons
Secondary pollutants: These are formed due to the chemical reaction among two or more pollutants.
e.g. Peroxyacetyl nitrate (PAN )

11. How to Define an Air Pollutant?
Basis: Chemicals present in the environment
Process:
Use composition of the clean air as a bench mark.
When the concentration of a chemical in air is above the bench mark, it is termed as an air pollutant .

12. Chemical Composition of Dry Air

13. Common Air Pollutants → Outdoor → Indoor SO2 Radon CO, CO2
The air pollution problem is encountered in both indoor as well as outdoor.
→  Indoor
Radon
Combustion by-products
CO, CO2, SO2, Hydrocarbons, NOx
Particulates, Polyaromatic hydrocarbons
Environmental Tobacco Smoke (ETS)
Volatile organic compounds
Asbestos
Formaldehyde
Biological contaminants
Pesticides
→ Outdoor
  SO2
  CO, CO2 
  Oxides of Nitrogen
  Ozone
  Total Suspended particles
Lead
Particulates
Volatile organic compounds
Toxic Air pollutants

14. Sources of Air Pollutants
Indoor
Outdoor

15. Physical Forms of an Air Pollutant
Gaseous form
  Sulfur dioxide
  Ozone
  Hydro-carbon vapors 
Particulate form
  Smoke
  Dust
  Fly ash
  Mists

16. 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.
The list of hazardous air pollutants can be found in the EPA website. (

17. Sources of Toxic Air Pollutants

18. Toxic Air Pollutants
The toxic air pollutants released from industrial facilities, in the United States, are reported to the public via the Toxic Release Inventory (TRI)
USEPA
“Major” sources are defined as sources that emit 10 tons per year of any of the listed toxic air pollutants, or 25 tons per year of a mixture of air.
“Area” sources are defined as sources that emit less than 10 tons per year of a single air toxic, or less than 25 tons per year of a mixture of air toxics.

19. Units for measurement of Air Pollution
   There are two units of measurement. They are as follows:
   µg/m3 and ppm (parts per million)
At 25°C and 1 atm
At 00 C and at a pressure of 76 cm of Hg, volume of the air is l/mol.
To obtain volume at any temperature, use gas law
P1V1/T1 = P2V2/T2

20. Sources of Air Pollution
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

21. Natural Sources vs. Man-made Sources
Pollutants released from natural sources like volcanoes, coniferous forests, and hot springs have a minimal effect on environment when compared to that caused by emissions from man-made sources like industrial sources, power and heat generation, waste disposal, and the operation of internal combustion engines.
Fuel combustion is the largest contributor to air pollutant emissions, caused by man, with stationary and mobile sources equally responsible.

22. 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.

23. 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 categories like forest fires, coal mining etc.

24. Problems

25. Exercise
The exhaust from a 2001 Honda contains 2.5% by volume of carbon monoxide. Compute the concentration of CO in milligrams/m3 at 25°C and 1 atm of pressure.

26. Exercise
Problem : The exhaust from a 2001 Honda contains 2.5% by volume of carbon monoxide. Compute the concentration of CO in milligrams/m3 at 25°C and 1 atm of pressure. Solution : Step 1 1 percent by volume = 104 ppm. 2.5 percent by volume = 2.5*104 ppm. Molecular Weight of CO is 28 g/mol Step 2 = 2.8 x 107 mg/m3

27. Exercise
Determine the actual volumetric flow rate in acfm assuming that pressure is constant, when the actual temperature is 400 F. The standard conditions are 70 F and 2000 cfm.

28. Exercise
Problem : Determine the actual volumetric flow rate in acfm assuming that pressure is constant, when the actual temperature is 400 F. The standard conditions are 70 F and 2000 cfm. Solution : Step 1 Temperaturestd = 70 F = 530 R. Temperatureact = 400 F = 860 R. Step 2 qact = qstd*(Tempact / Tempstd). = 2000*(860 / 530). = acfm

29. Exercise
Calculate the density of a gas whose molecular weight is 29 at 1 atm, absolute and 50°F.

30. Exercise Problem : Step 2
Calculate the density of a gas whose molecular weight is 29 at 1 atm, absolute and 50°F.
Solution :
Step F     = = 510 R
R = 0.73 atm-ft3 /lb mol-R.
Step 2
density = P * mol.wt/RT  
density = (1*29)/(0.73*510)
=  lb/ft3.