Geoscience Reference
In-Depth Information
500
11.10. Regulation of Chlorofluorocarbons
The effects of CFCs on ozone were first hypothesized
by
Mario Molina
and
Sherwood Rowland
in June
1974. As early as December 1974, legislation was intro-
duced in the U.S. Congress to study the problem further
and give the U.S. EPA authority to regulate CFCs. This
bill died before any action was taken. In 1975, Congress
established a committee that ultimately recommended
that spray cans, the primary emitters of CFCs, be
labeled in such a way as to identify whether they con-
tained CFCs or an alternative compound. In 1976, the
U.S. National Academy of Sciences released a report
suggesting that CFC emissions were large enough to
cause a long-term 6 to 7.5 percent decrease in global
stratospheric ozone, potentially increasing surface
UV-B radiation by 12 to 15 percent. On the basis of this
report, the U.S. Food and Drug Administration, the U.S.
EPA, and the Consumer Product Safety Commission
issued a joint decision suggesting the phase-out of CFCs
from spray cans. In October 1978, the manufacture and
sale of CFCs for spray cans was banned in the United
States. At the time, the United States was responsible
for half the global production of CFCs used in spray
cans.
Although overall CFC emissions decreased as a result
of the ban of CFCs in spray cans, tropospheric mixing
ratios of CFCs continued to increase due to the fact that
emission of CFCs from other sources still occurred.
Throughout the late 1970s and much of the 1980s, the
use of CFCs in refrigeration and foam production and
as a solvent increased. To limit damage due to CFCs,
rules were contemplated for reducing their emission
from all sources. In 1980, the U.S. EPA proposed pre-
venting emission growth of CFCs from refrigeration,
butthe proposed regulations were thwarted by the new
presidential administration.
On the international front, the Vienna Convention
for the Protection of the Ozone Layer was convened in
March 1985 to discuss CFCs. The result of this conven-
tion was an agreement, signed initially by twenty coun-
tries, stating that signatory countries had an obligation
to reduce CFC emissions and to study further the effect
of CFCs on ozone. In September 1987, an international
agreement, the
Montreal Protocol
,was signed initially
by twenty-seven countries, limiting the production of
CFCs and halons and setting a timetable for their even-
tual phase-out. The Montreal Protocol was modified
several times, including by the London Amendments
(1990), Copenhagen Amendments (1992), and Mon-
treal Amendments (1997), to expedite the phase-out of
CFC11
CFC12
HCFC-22
HCFC-142b
HCFC-134a
HFC-125
HFC-143a
400
300
200
100
0
1940
1960
1980
2000
Year
Figure 11.20.
Production of selected CFCs, HCFCs,
and HFCs by reporting companies only, between
1931 and 2007. Nonreported emissions are estimated
to account for 60 percent of CFC production,
10 percent of HCFC-22 production, and 0 percent of
HFC-134a production. CFC, chlorofluorocarbon;
HCFC, hydrochlorofluorocarbon; HFC,
hydrofluorocarbon. From Alternative Fluorocarbons
Environmental Acceptability Study (AFEAS) (n.d.).
CFCs. The modified protocol called for the phase-out
of CFC-11 and -12 by 1996, as well as a phase-out of
other CFCs and halons by 2010.
The major effect of the Montreal Protocol, later
amendments, and previous regulations to ban the use
of CFCs in spray has been the near elimination of CFC
emissions but a corresponding increase in CFC substi-
tutes, namely, HCFCs and HFCs. Figure 11.20 shows
the emissions from major CFCs, HCFCs, and HFCs
produced by reporting companies between 1931 and
2007. Reporting companies include eleven major man-
ufacturers who are estimated to account for 40 percent
of the worldwide production of CFCs, 90 percent of the
worldwide production of HCFC-22, and 100 percent
of the worldwide production of other HCFCs and all
HFCs. Most remaining CFCs and HCFC-22 are pro-
duced in Russia and China.
Figure 11.20 indicates that HCFC emission rates
increased from 1970 to the early 2000s but have since
declined. The reason for the decline is that the Montreal
Protocol and its amendments required the phase-out of
HCFCs starting in 1996. Although HCFCs break down
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