1. Greenhouse effect

2. Greenhouse Gases Water vapor (H2O) - evaporation
Carbon Dioxide (CO2) – burning fossil fuels
Nitrogen oxides (NOx) – vehicle exhaust
Sulfur oxides (SOx) – factory pollution
Ground level Ozone (O3) - Vehicles
CFC’s - aerosols

4. Photochemical Smog Chemical reaction that is activated by light
Example: Nitrogen and Oxygen
N2 + O2  2NO
2NO + O2  2NO2 (smog)
3NO2 + H2O  2HNO3 + NO
NO2 + UV radiation  NO + O
O + O2  O3 (ground-level o-zone)

5. Photochemical Smog
Ozone levels peak on hot days during rush hours and in the early afternoon
NOx is released from cars during this time
What do London, Pittsburgh, and Chicago have in common during the Industrial Revolution?
Burned LARGE amounts of coal and oil which released SOx into the atmosphere

6. Pittsburgh, Pennsylvania
Circa. 1906

7. Industrial Smog Pollution from factories and coal power plants
Sulfur dioxide (SO2), sulfuric acid (H2SO4), suspended particulates
Chemistry of coal:
C + O2  CO2 & 2C + O2  CO2 & *soot
S + O2  SO2; lead sulfides from minerals
2SO2 + O2  2SO3
SO3 + H2O  H2SO4
H2SO4 + 2NH3  *(NH4)2SO4

8. Smog Frequency and severity of smog depends on:
Climate
Topography (Mountains)
Population density
Industry
Precipitation “cleans” the air
Winds bring fresh air, mixes the atmos., and move the smog
Tall buildings, Hills and mountains, and high temperatures help smog formation

9. Smog Layer over Los Angeles
Warm Air
Inversion Layer
Temperature inversion: when temperatures RISE in the troposphere