1. What Causes Air Pollution?
Chapter 12-1
What Causes Air Pollution?

2. Warm-up

3. Layers of the atmosphere
Four layers:
Troposphere
Stratosphere
Mesosphere
Thermosphere

4. troposphere
Densest of the atmospheric layers
Almost all weather occurs here

5. stratosphere
Ozone layer (O3)
Ozone absorbs UV radiation
3O2 + UV  2O3

8. Mesosphere
Very cold!
Meteorites

9. thermosphere
Very high temperatures
Absorbs harmful solar radiation (X rays and gamma rays)

10. Temperature in the atmosphere

11. What Causes Air Pollution?
Solids, liquids, or gases.
Most air pollution is the result of human activities

12. What Causes Air Pollution?
Some natural: dust, pollen, spores, and sulfur dioxide from volcanic eruptions
Condensation nuclei

13. Categories of air pollutants
Primary pollutants
Secondary pollutants

14. Major outdoor air pollutants
Carbon oxides:
Carbon monoxide (CO)
Carbon dioxide (CO2)

15. Major outdoor air pollutants
NOx (nitrogen oxide and nitrogen dioxide)
Nitrogen oxide (NO)
Nitrogen dioxide (NO2)
NOx play a role in the formation of photochemical smog

16. Major outdoor air pollutants
SOx (sulfur dioxide and sulfuric acid)
Sulfur dioxide (SO2)
Sulfuric acid (H2SO4)

17. Major outdoor air pollutants
Particulates
Suspended particulate matter (SPM) – consists of a variety of solid particles and liquid droplets. Remain suspended in air.
Sources
Natural –
Human –

18. Major outdoor air pollutants

19. Major outdoor air pollutants
Ozone (O3)
Volatile organic compounds (VOCs)

20. Major outdoor air pollutants

21. Secondary pollutant formation

22. Primary pollutants

23. History of air pollution
The world’s air quality problem is much worse today because modern industrial societies burn large amounts of fossil fuels.
Most air pollution in urban areas comes from vehicles and industry.
London Smog

24. Case Study: Donora, PA

25. Motor vehicle emissions
Almost 1/3 of our air pollution comes from gasoline burned by vehicles.
Over 90% of that mileage was driven by passenger vehicles.
The rest was driven by trucks and buses.

26. Controlling vehicle emissions
The Clean Air Act (1970, strengthened in 1990)
Environmental Protection Agency (EPA) the authority to regulate vehicle emissions in the USA
Gradual elimination of lead in gasoline
Catalytic converters required in all automobiles

27. Controlling Vehicle Emissions

28. California Zero-Emission Vehicle Program
In 1990, the California Air Resources Board established the zero-emission vehicle (ZEV) program.
Zero-emission vehicles are vehicles that have no tailpipe emissions, no emissions from gasoline, and no emission-control systems that deteriorate over time.
By 2016, 16 percent of all vehicles sold in California are required to be zero- emission vehicles, including SUVs and trucks.

29. California Zero-Emission Vehicle Program
ZEVs:
Electric vehicles
Hydrogen fuel cells vehicles
Hybrid-electric cars (Partial ZEV)