smog, pollution

1. Urban ozone: The photochemical smog
• Action of sunlight upon the exhaust gases to
form pollutants harmful at low altitudes.
• Smog: combination of smoke and fog
VOC + NO + O2 + sunlight (primary pollutants)
O3, HNO3, organics (secondary pollutants)

2. The photochemical smog

3. • Photochemical Smog
(Brown smog)
– Mexico City
– Los Angeles, CA
– Photochemical oxidants
– nitrogen oxides

4. • Industrial Smog
(Gray Smog)
– China; NYC, India
– London during Industrial
Revolution 1952
– Burning coal; soot, CO,
Mercury and sulfur

5. Acid Deposition

6. Acid Deposition Effects
• Respiratory diseases
• Metal leaching –Al ions in soil; Mg ions loss for
plant uptake (non-toxic)
• Damage to structures, especially containing
calcium carbonate
• Decreased visibility
• Fish declines
• Coral bleaching

7. Emission
Acid
deposition
SO2
H2O2
PANs
NOX
O3
Other
s
Direct damage
to leaves and bark
Reduced
photosynthesis
and growth
Increased
Susceptibility
to drought,
extreme cold,
insects, mosses,
and disease
organisms
Soil acidification
Leaching of
Soil
nutrients
Acid
Release of
toxic
metal ions
Root
damage
Reduced nutrient
and water uptake
Tree death
Groundwater

8. Uses of Chloro-Fluoro-Carbons(CFC)
• Uses of CFCs prior to the 1987 Montreal Protocol
• 26% refrigeration
• 26% aerosols
• 25% Foams
• 16% Solvents
• 7% others

9. Uses of Chloro-Fluoro-Carbons(CFC)
• CFCs are chemically inert and are not broken down
at low altitudes
• Insoluble in water so they are not washed from the
atmosphere in rain
• Remain the troposphere for long periods of
time, and diffuse to the stratosphere
• CFCs in the stratosphere cause damage to the
protective ozone layer

10. Effects of Ozone Depletion
Human Health
• Worse sunburns
• More eye cataracts
• More skin cancers
• Immune system suppression
Food and Forests
• Reduced yields for some crops
• Reduced seafood supplies from
reduced phytoplankton
• Decreased forest productivity for
UV-sensitive tree species
Wildlife
• Increased eye cataracts in some species
• Decreased population of aquatic species
sensitive to UV radiation
• Reduced population of surface
phytoplankton
• Disrupted aquatic food webs from reduced
phytoplankton
Air Pollution and Materials
• Increased acid deposition
• Increased photochemical smog
• Degradation of outdoor paints and plastics
Global Warming
• Accelerated warming because of decreased
ocean uptake of CO2 from atmosphere by
phytoplankton and CFCs acting as
greenhouse gases

11. Protecting the Ozone Layer
CFC substitutes -long term
replacement by HFC
Montreal Protocol- 1987 limits/ bans CFC’s ;
production stopped in 1995; India and China not a part of the treaty
Montreal Protocol- An international treaty designed
to protect the ozone layer