OZONE

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OZONE

• In 1994, the United Nations General Assembly
  voted to designate September 16 as "World Ozone
  Day", to commemorate the signing of the Montreal
  Protocol on that date in 1987.

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Bad Ozone

• LA (and Houston) photochemical smog

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Ozone in the lower troposphere especially in
urban areas is bad ozone.  In urban
environments sunlight can combine with fossil
fuel combustion byproducts (oxides of nitrogen
and some hydrocarbons) to create ozone.  Ozone
is a major component of this photochemical smog
and can irritate eyes, throats, lungs, and
vegetation.  Ozone concentrations during ozone
alert days can be dangerous to those with chronic
lung disease.
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Good Ozone
http//www.theozonehole.com/
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http//www.theozonehole.com/ (Antarctic Polar
Vortex)
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History

• CFC introduced 1928 by DuPont

Replacing earlier toxic refrigerants (ammonia
(NH3), methyl chloride (CH3Cl), and sulfur
dioxide (SO2)) and allowing widespread
introduction of refrigerators into the public
market during after 1930.
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1930s. Chapman proposed that stratospheric ozone
was created by sunlight and oxygen, and destroyed
by sunlight and oxygen.
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1960s.  Measurements of ozone showed that the
Chapman reactions were not sufficient to explain
the lower than expected ozone levels in the
atmosphere.
NO can also be replaced by natural occurring Cl,
Br, H, and O
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Catalytic destruction of ozone
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Estimated for the year 2000
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Early 1970s.    Paul Crutzen from Germany,
realized that elevated stratospheric nitrogen
levels resulting from elevated tropospheric N2O
could increase NO in the stratosphere and destroy
Ozone.
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Early 1970s.    The proposal of a supersonic
airline fleet resulted in an assessment of such a
fleet on the ozone layer.  Paul Crutzen from
Germany, among many other scientists, realized
that elevated stratospheric hydrogen and nitrogen
levels resulting from super sonic aircraft
exhaust could be damaging to ozone layer.
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1974.  Sherwood Rowlin and Mario Molina report
that the increasing levels of chlorofluorocarbons
observed by James Lovelock could result in
elevated stratospheric chlorine levels and hence
damage stratospheric ozone. 
Since chlorine is a catalyst for ozone
destruction a single chlorine atom can
participate in the destruction of many ozone
molecules.
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1978.  US bans non-essential use of CFCs ie.
aerosol sprays.  CFCs are still used as
refrigerants as well as other applications. 
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1979-1984.  Much debate about the predictions of
Rowlin and Molina.  Some scientists accused them
of scaring the public with chicken little "The
sky is falling " tactics.
(1992) Available on Amazon for 0.01
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1985.   Farman, Gardinar and Shanklin from the
British Antarctic Survey. Published results from
ozone measurement at Halley Antarctic Research
Station in _Nature_, May 1985.
Average October ozone levels recorded by Farman's
group at Halley Bay, Antarctica, from 1957
through 1984. http//undsci.berkeley.edu/article/
0_0_0/ozone_depletion_09
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1986.  Susan Solomon and other atmospheric
chemists note that chemical reactions on polar
stratospheric clouds make the threat to
stratospheric ozone much worse than originally
proposed by Rowlin and Molina.
Polar Stratospheric Clouds (PSCs) a.k.a. Mother
of Pearl
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1986.  Susan Solomon and other atmospheric
chemists note that chemical reactions on polar
stratospheric clouds make the threat to
stratospheric ozone much worse than originally
proposed by Rowlin and Molina.
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1987.  The most recent world resolution regarding
the problem of ozone depletion is the Montreal
Protocol. The original Montreal Protocol was
signed in the fall of 1987, based on negotiations
started between european-scandinavian countries
and the US over CFC's in aerosol sprays in 1983.
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1995.  Crutzen, Rowlin, and Molina share the
Nobel prize in chemistry for their efforts at
understanding ozone chemistry and the ozone hole.
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http//www.esrl.noaa.gov/gmd/dv/spo_oz/
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http//www.esrl.noaa.gov/gmd/dv/spo_oz/
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1998 to present.

• Scientist explore the connection between climate
  change and ozone.  Most climate models predict
  that increased levels of greenhouse gases in the
  atmosphere will
• 1) raise near surface temperatures (Global
  warming)
• 2) result in colder stratospheric temperatures. 

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1998 to present.

• Colder stratospheric temperatures may
• 1) enhance the occurrence of polar stratospheric
  clouds and the polar vortex strength which could
  delay the recovery of the Antarctic ozone hole
• 2) enhance the strength of the Arctic polar
  vortex and the occurrence of Arctic polar
  stratospheric clouds which could result in an
  Arctic ozone hole similar to that in the
  Antarctic.

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