fires and other forms of biomass burning, volcanic activities, and marine algae,
which produce millions of tons of methyl bromide annually. Bromine, which is
found in much smaller quantities than chlorine, is about 50 times more effective
than chlorine in its effect on stratospheric ozone depletion and is responsible for
about 20% of the problem.
Effects of Ozone Depletion
During the onset of the 1998 Antarctic spring, a hole three times the size of
Australia (over 3,500 miles [5,600 km] in diameter) developed in the ozone layer
over the South Pole.
Harmful effects of increased UV radiation include:
■ Increases in skin cancer ■ Increases in sunburns and damage to the skin
(premature aging) ■ Increases in cataracts ■ A reduction in crop
production ■ Deleterious effects on animals (since they don’t wear
sunglasses or sunscreen) ■ A reduction in the growth of phytoplankton
and the cumulative effect on food webs ■ Increases in mutations, since
UV radiation causes changes in the DNA structure ■ Cooling of the
stratosphere ■ A reduction in the human body’s immune system
■ Climatic changes Strategies for Reducing Ozone Depletion
Two of the most popular and current substitutes for CFCs are HCFCs
(hydrochlorofluorocarbons) (e.g., Puron® is used as a refrigerant for air
conditioners) and HFCs (hydrofluorocarbons). The main advantage that HCFCs
and HFCs have over CFCs is that they are much less stable and more reactive
with their additional hydrogen atom(s) (i.e., they can usually break down in the
troposphere before reaching the stratosphere and destroying ozone). However,
the disadvantage is that they have global warming greenhouse gas potentials up
to 1,725 times greater than that of carbon dioxide.
Research is underway to find alternatives to the current use of HCFCs and
HFCs. For example, Opteon®, the next-generation refrigerant and replacement
for Puron®, has a greenhouse warming potential of 4, with virtually no effect
on the ozone layer.
RELEVANT PROTOCOL
MONTREAL PROTOCOL: The Montreal Protocol is an international