Day 011 - 12 Jul 94 - Page 33


     
     1        is all transported into the stratosphere, where it is
              photodissociated to liberate two active chlorine atoms
     2        which then catalytically destroy ozone.  Its ODP is
              therefore high.  Methyl chloroform on the other hand ---"
     3        We do not describe, or do we describe, that as a CFC?
              A.   It is not a CFC because it does not contain chlorine.
     4
         Q.   "... On the other hand, although it contains three
     5        chlorine atoms, has a much shorter lifetime since it is
              destroyed chemically in the troposphere.  Its ODP is
     6        therefore low ---"
 
     7        Substituting HCFC- 22 for methyl chloroform, would that
              statement now correspond with what we know about HCFC- 22?
     8        A.   Yes.
 
     9   Q.   ".... About one- tenth of CFC- 11 Halon 1301, with a long
              lifetime and one bromine atom, has a very high ODP value,
    10        since a bromine atom can react with ozone a large number
              of times before being converted to a more inactive
    11        chemical form."
 
    12        Then there is some material about the Montreal Protocol
              and then a reference to a table showing best estimates of
    13        lifetimes which is the table you drew attention to
              earlier.  That is at page 43, Table 4.1, where we see CFCs
    14        11 and 12 mentioned with lifetimes respectively of 77 and
              139 years at the top of the second column.  We do see some
    15        HCFCs mentioned at the bottom of the left hand column, do
              we not?
    16        A.   Yes.
 
    17   Q.   That ought to have relatively short lifetimes- 2, 5 and 10
              respectively, are they not?
    18        A.   Yes.  HCFC- 22 is actually in the middle of that page
              and that is thought to be 22 years.
    19
         Q.   I missed that one.  Well spotted- 22 years, although as we
    20        saw, its estimated lifetime was later reduced to just over
              fifteen.  Then going back to page 46 there is a pie chart
    21        which shows the attributed responsibility to these various
              substances, with CFC- 12 thought to be the greatest
    22        culprit by some way.  Is that right?
              A.   It is.
    23
         Q.   Can we move on to 1990. That is at Tab C.  Here we will
    24        see the executive summary on the sixth page.  Again, I am
              not going to read the whole of it.  The first paragraph,
    25
               "Recent evidence from atmospheric measurements in polar 
    26        regions reinforces the conclusion reached in SORG 1988 
              that substantial damage has occurred to the ozone layer 
    27        due to reactive chlorine and bromine derived from man-
              made CFCs and halons."
    28
              What are 'halons'?
    29        A.   Halons are the compounds which contain bromine and
              their primary use is in fire extinguishers.
    30
         Q.   Then there is some history in paragraphs 2, 3, and 4.  In

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