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| Doesn't look too good, but the hole was bigger in the '90s. |
Good
news for those of you that do not wear sun screen! Recent measurements show
that the hole in the ozone layer is slowly filling back in, and it is not just
a natural process that is causing this, it is a change in human action. Through
a combination of international cooperation and internal regulation that is rarely
seen in politics, the world banded together to combat an issue that very well
could have led to the end of life as we know it. So what is ozone and why was
it in danger? How did we stop it and why did we bother? For the sake of
simplicity, I am going to focus on the actions of the United States and how
they contributed to saving the ozone layer. The simplicity, however, does not
save you from a short chemistry lesson that is integrally important in
understanding this issue.
Most
people know that the chemical formula of the oxygen we breathe is O2.
In the upper atmosphere of the earth, these ordinary oxygen molecules are hit
with ultraviolet (UV) rays from the sun. This energy can break the bonds of the
normal oxygen and cause it to link with another oxygen molecule to form ozone,
the chemical formula of which is O3. The ozone is also hit by the
radiation and a bond breaks, turning it back into normal a normal oxygen
molecule. This process happens back and forth repeatedly in the upper
atmosphere, largely shielding humans, and all other life forms for that matter,
from harmful levels of cancer causing UV rays.
From
the 60’s onward, humans were finding creative and productive uses for nifty
little compounds called chlorofluorocarbons (CFCs). These gaseous chemicals,
composed of chlorine, fluorine, and carbon, were used in everything from
aerosol sprays to refrigeration to insulation during this time. Two decades
later in the early 80’s, scientists realized that the levels of ozone in the
upper atmosphere were rapidly declining. They rushed to find what was causing
the depletion and found that it was the CFCs that were creating this issue. The
CFC gas often leaked into the atmosphere during production and out of products
that were not well maintained. When this gas reached the upper atmosphere, it encountered
the UV rays and some of its chlorine bonds broke. As chorine is very reactive,
it can easily strip oxygen off of surrounding ozone molecules. The free oxygen
atoms that help create ozone in the first place then link with the chlorine
atoms or other free oxygens instead of to an oxygen molecule. This throws the
balance of ozone creation and depletion off, eventually leading to an area
around the South Pole where there is not enough ozone to shield the planet from
UV rays.
After
discovering this alarming trend, scientists were quick to let the public know
what the problem was and what was creating it. Public fear and outrage over
this and other environmental catastrophes led to the green movement and
ultimately two important pieces of legislation that decreased worldwide use of
CFCs and ozone depleting products (ODPs). The first was the Montreal Protocols.
Alarmed that the ozone layer was thinning, concerned delegates from most UN
member countries gathered in Helsinki to do something about it. The plan they
eventually came up with in 1987 was the Montreal Protocols which outlined the
plans and timetables of decreasing and eliminating use of ODPs and CFCs.
Eventually this plan was ratified by all UN member states. This led to a
significant increase into ODP alternatives and a gradual decrease in CFC usage.
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| A chart showing the projected atmospheric concentration of ODPs with and without the Montreal Protocol. |
As is the case with many
environmental laws in the United States, there was stiff opposition to the plan
by some chemical companies and businesses. This is where the second piece of
legislation, the Clean Air Act (which had just been strengthened in 1990),
comes into play. This law give the EPA the ability to investigate, fine, and
shut down violators of the Clean Air Act, as well as lists prohibited chemicals
due to their ozone depleting properties. These actions ensured the gradual yet
significant drop in the usage of CFCs.
Sources:
http://www.epa.gov/ozone/mbr/index.html
http://en.wikipedia.org/wiki/Montreal_Protocol
http://www.epa.gov/ozone/strathome.html
http://www.epa.gov/air/caa/requirements.html
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