Air Pollution

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The OZONE Hole
Excess ozone in the lower atmosphere is
(generally) bad.
Pollution also causes losses in ozone in the
upper atmosphere, which is bad.
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Outer space
OZONE LAYER
30 miles
Good ozone Bad ozone
6 miles
Mt Everest, 8,848 m
Ground
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Why holes over the poles?
Chlorofluorocarbons (CFCs)
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Circumpolar winds transport air pollution from
heavily industrialized regions to the Arctic,
where high levels of smog accumulate.
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Dobson unit 0.001mm at standard pressure and
temp 300 2 pennies thick, but solid O3 gas.
Instead, this gas is diffuse through
stratosphere (24 miles thick)
The British Antarctic Survey (BAS)
Jonathan Shanklin of BAS
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CFC Production
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The persistent ozone hole
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How long does Chlorine remain in the atmosphere?

• Most of it hours to days.
• Most CL in atmosphere enters from salt spray and
  resides in the atmosphere for very short periods
  of time.
• Chlorine transported to the upper atmosphere by
  CFCs can remain for much longer 20-100 years!

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Controlling OZONE destruction
1974 - Scientific study suggests theoretical
link between CFCs and ozone destruction 1985
- discovery of ozone hole 1985 - Vienna
Convention on Substances that Deplete the Ozone
Layer 1986 - DuPont begins research into HCFCs
1987 - U.S. bans use of CFCs in aerosols (US a
major manufacturer) 1987 - Montreal Protocol on
Substances that Deplete the Ozone Layer 1988 -
DuPont announces intention of stopping production
of CFCs 1988 - McDonalds switches away from
CFC-produced packaging 1988 - ozone losses 2 - 3
times as severe as predicted by models
locally up to 95 over Antarctica 1990 -
London Agreement (expands banned chemical list,
speeds up phase out) 1992 - severe ozone
depletion recorded in Northern Hemisphere 1992 -
Copenhagen Agreement (expands banned chemical
list, speeds up phase out) 1995 Venice amendment
(methyl bromide phaseout agreed upon) 2000
predicted Cl pool hits maximum and ozone begins
to recover
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Controlling OZONE destruction
1. Each step since the Montreal Protocol
(London, Copenhagen, Venice) has been to further
limit and restrict ozone destroying
chemicals. 2. This has been made possible by a
technological solution (alternatives).
Black market CFCs continue and policing the end
of all use will be hard
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Perhaps the single most successful international
agreement to date has been the Montreal Protocol.
 "-Kofi Annan, Secretary General of the United
Nations
Summary of Montreal Protocol Control Measures
www.ozonehole.com

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CFC Production
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Methyl bromide

• Used to kill bacteria and insects on fruits and
  vegetables.
• Widely used
• A human health hazard (carcinogen)
• A ozone hazard
• Short atmospheric lifetime (lt 2 years)
• Very high capacity for damage (50 x CFCs)
• Br, like Cl, has a strong ionic bond potential
  and strips electrons driving decomposition of O3

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Who?
18th meeting in New Delhi
21 of 1991 baseline amount
EPA allocation
EPA
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Greenhouse gases CO2, methane,...
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What we know for certain

• The concentration of heat trapping gases in the
  atmosphere is rising
• The earths temperature is rising
• The scale of both is consistent with human caused
  global warming