Scientists have found "holes"[3]
in the ozone layer high above the Earth. The 1990 Clean Air Act has provisions
for fixing the holes, but repairs will take a long time.
[3] Ozone holes aren't like doughnut
holes; they're not empty spaces in the sky. Ozone holes are much like the
worn-out places in an old sock or sweater: there are still threads covering
the worn-out area, but the fabric can be so thin you can see right through it.
Ozone in the stratosphere, a
layer of the atmosphere nine to 31 miles above the Earth, serves as a
protective shield, filtering out harmful sun rays, including a type of
sunlight called ultraviolet B. Exposure to ultraviolet B has been
linked to development of cataracts (eye damage) and skin cancer.
In the mid 1970s, scientists suggested
that chlorofluorocarbons (CFCs) could destroy stratospheric ozone. CFCs were
widely used then as aerosol propellants in consumer products such as
hairsprays and deodorants, and for many uses in industry. Because of concern
about the possible effects of CFCs on the ozone layer, in 1978 the U.S.
government banned CFCs as propellants in aerosol cans.
Since the aerosol ban, scientists have been measuring the ozone
layer. A few years ago, an ozone hole was found above Antarctica, including
the area of the South Pole. This hole, which has been appearing each year
during the Antarctic winter (our summer), is bigger than the continental
United States. More recently, ozone thinning has been found in the
stratosphere above the northern half of the United States; the hole extends
over Canada and up into the Arctic regions (the area of the North Pole). The
hole was first found only in winter and spring, but more recently has
continued into summer. Between 1978 and 1991, there was a 4-5 percent loss of
ozone in the stratosphere over the United States; this is a significant loss
of ozone. Ozone holes have also been found over northern Europe.
What could a thinned-out ozone layer do
to people's lives? There could be more skin cancers and cataracts. Scientists
are looking into possible harm to agriculture, and there is already some
evidence of damage to plant life in Antarctic seas.
Evidence that the ozone layer is
dwindling led 93 nations, including the major industrialized nations, to agree
to cooperate in reducing production and use of chemicals that destroy the
ozone layer. As it became clear that the ozone layer was thinning even more
quickly than first thought, the agreement was revised to speed up the
phase-out of ozone-destroying chemicals.
Unfortunately, it will be a long time
before we see the ozone layer repaired. Because of the ozone-destroying
chemicals already in the stratosphere and those that will arrive within the
next few years, ozone destruction will likely continue for another twenty
years.
The 1990 Clean Air Act sets a schedule
for ending production of chemicals that destroy stratospheric ozone. Chemicals
that cause the most damage will be phased out first. The phase-out schedule
can be speeded up if an earlier end to production of ozone-destroying
substances is needed to protect the ozone layer. The table on this page on Ozone-destroying
chemicals includes "speeded-up" phase-out dates which were
proposed by EPA in early 1993.
*The 1990 Clean Air Act includes a
schedule for ending United States production of ozone-destroying chemicals and
provisions for speeding up the phase out schedule if that is necessary. The
dates in this table are "speeded-up" dates, proposed by EPA in early
1993.
**Production of the HCFC with the
most severe ozone destroying effects will end by January 1, 2003. Production
of the rest of the HCFCs will end by January 1, 2030.
CFCs, Halons, HCFCs (hydrochlorofluorocarbons)[4]
and other ozone-destroying chemicals were listed by Congress in the 1990 Clean
Air Act and must be phased out. The Act also lets EPA list other chemicals
that destroy ozone.
[4] HCFCs and Halons are chemicals
much like CFCs. HCFCs may be somewhat less harmful to the ozone layer than are
CFCs.
EPA issues allowances to control
manufacture of chemicals being phased out. Companies can also sell unused
allowances to companies still making the chemicals or can use the allowances,
within certain limits, to make a different, less ozone-destroying chemical on
the phase-out list.
In addition to requiring the phasing out
of production of ozone-destroying chemicals, the Clean Air Act takes other
steps to protect the ozone layer. The law requires recycling of CFCs and
labeling of products containing ozone-destroying chemicals. The 1990 Clean Air
Act also encourages the development of "ozone-friendly" substitutes
for ozone-destroying chemicals.
CFCs from car air conditioners are the
biggest single source of ozone-destroying chemicals. By the end of 1993, all
car air conditioner systems must be serviced using equipment that recycles
CFCs and prevents their release into the air. Larger auto service shops were
required to start using this special equipment in January 1992. Only
specially-trained and certified repair persons will be allowed to buy the
small cans of CFCs used in servicing auto air conditioners.
As CFCs and related chemicals are phased
out, appliances and industrial processes that now use the chemicals will
change. For example, industrial and home refrigerators will be changed to use
refrigerants that don't destroy ozone. In the meantime, refrigerator servicing
and disposal will have to be done in ways that don't release CFCs. Methyl
chloroform, also called l,l,l-trichloroethane, which will be phased out by
1996, is a very widely-used solvent found in products such as automobile brake
cleaners (often sold as aerosol sprays) and spot removers used to take greasy
stains off fabrics. Replacing methyl chloroform in workplace and consumer
products will lead to changes in many products and processes.
As substitutes are developed for
ozone-destroying substances, before the chemicals can be produced and sold,
EPA must determine that the replacements will be safe for health and the
environment.
Consumer products containing CFCs and
other ozone-destroying chemicals will have to be reformulated.
