1. Air Pollution

2. The air we breathe Clean air consists of: Nitrogen Oxygen
Very small amounts of argon, carbon dioxide and water vapor.
We breathe 3,000 gallons of air each day.
When harmful substances reach unhealthy levels we call this “air pollution.”

3. Layers of Earth’s atmosphere
Troposhere: provides us with the air we breathe. Extends 7 miles high. Responsible for weather
Stratosphere: 7-31 miles. Contains the ozone layer. Stratosheric ozone scatters UV radiation
Mesosphere: miles high
Thermosphere: top layer, extends to 300 miles

4. Thermal Inversion
In the troposphere warm air rises, mixes with cooler air and pollution dissipates
In mountain valleys slopes block morning sun, air at ground level remains cool
Warm air at altitude traps pollutants near the ground
Ex: Los Angeles, Mexico City, Rio de Janeiro, Sao Paulo

5. The London Smog of 1952
In 1952, London abandoned their electric tramcars in favor of diesel buses.
This added to pollution already coming from burning coal
December 1952 was cold and foggy.
The air pollution was trapped by an inversion layer above
An estimated 4,000 people died from respiratory problems

7. Air Pollution Most air pollution is man-made.
Natural air pollution includes volcanic ash, dust, pollen, and spores.
Primary Pollutant: one that is put directly into the air by human activity ex. Soot, CO
Secondary Pollutant: forms when two primary pollutants interact, or when one combines with a naturally occurring substance ex. ground level ozone, Sulfuric acid

8. The Clean Air Act (1970)
The Clean Air Act gave the federal government authority to clean up air pollution.
EPA set maximum limits on pollutants that can be in the air (National Ambient Air Quality Standards)
EPA limits emissions from industry
EPA regulates vehicle emissions and required the gradual elimination of lead from gasoline

9. Clean Air Act of 1990 Strengthened regulations on: Auto emisions
Toxic air pollution (188 pollutants incl. mercury, benzene)
Acid rain
Stratospheric ozone pollution
Emissions trading for SO2

10. Criteria Air Pollutants
Carbon Monoxide
Nitrogen Oxides
Sulfur Dioxide (SO2)
Particulate Matter
Troposheric (ground level) ozone
Lead

11. Carbon monoxide (CO) Odorless, colorless, poisonous
Produced by the incomplete burning of fossil fuel
Sources include vehicles, burning propane or natural gas indoors, faulty furnaces
500 Americans die each year from accidental CO poisoning
Affects blood’s ability to carry oxygen.

12. http://www. epa. gov/cgi-bin/broker

13. Nitrogen Oxides (NOX) Foul smelling, reddish brown gas
From vehicle exhausts, coal burning power plants, industry
Contributes to smog and acid rain
Makes your body vulnerable to respiratory disease and cancer

15. Sulfur Dioxide (SO2) Colorless gas with pungent odor
Produced by interactions between sulfur and oxygen
Comes from burning of coal and oil which contain sulfur
Contributes to acid rain as sulfuric acid
Harms plants and irritates human respiratory system

17. Particulate Matter (PM)
Particles of liquid or solid small enough to be suspended in the atmosphere
Fine particles come from vehicles, coal burning power plants. Coarse particles come from cement plants, mining and agriculture
Can form clouds that reduce visibility.
Can cause a variety of respiratory problems and cancer.

19. Troposheric (ground level) ozone
Ozone (O3) is a gas composed of three oxygen atoms.
Not usually emitted directly into the air (secondary pollutant)
Created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.
O3 is unstable. It readily releases an O atom producing O2 and free O atom.
Free O can damage living tissues and cause respiratory problems
This is the pollutant that most often exceeds EPA NAAQS.

20. Ozone: good up high, bad nearby!
High Altitude (stratosperic) ozone protects life on Earth from harmful UV rays.
Man-made chemicals, such as CFC’s, have depleted our ozone layer.
Since 1987 we have practically eliminated the use of ozone depleting substances
Our ozone layer is recovering

21. Health Effects of Ground level ozone
Airway irritation, coughing, and pain when taking a deep breath;
Wheezing and breathing difficulties during exercise or outdoor activities;
Inflammation, which is much like a sunburn on the skin; 
Aggravation of asthma and increased susceptibility to respiratory illnesses like pneumonia and bronchitis
Permanent lung damage with repeated exposures.

22. Lead Heavy metal found as a particulate Once found in gasoline
Lead was found to enter the food chain, accumulate in tissues, causes central nervous system damage
Today’s sources: industrial metal smelting
Lead paint

23. Volatile Organic Compounds (VOC)
Organic compounds that easily become toxic gas
Vehicles are a major source, also found in household products (paint, varnish, dry cleaned clothing, air freshener)
Contribute to smog formation
Cause serious health problems including cancer

25. Air Pollution has decreased since 1970

26. Case Study - China
China is building coal fired power plants at a rate of one each week
According to the World Bank 16 of the worlds 20 cities with the worst air are in China.