Ozone Depletion

Good morning, ladies and gentlemen. I am Aoi Koyanagi. Today Iím going to present my research on ozone depletion. Iím interested in this topic because the cause of the recent rapid increasing of ultraviolet rays from which Iíd like to protect my skin as much as possible is ozone depletion. Everyone already knows the topic of ozone depletion, for example, the ozone hole over the Antarctic. So I want to know the mechanism and the influences of ozone depletion.

Iím going to cover four points. First, I will show what the ozone layer is. Second, I will tell you about things which break the ozone layer. Third, I will explain the effects of ozone depletion. Finally, I will cover the status quo and out look in the future.

First, what is the ozone layer? According to the SEDAC Website it is compromised of Oxygen made into ozone by lightning in the stratosphere. The role of the Ozone layer is blocking ultraviolet rays, especially UV-B. There are three kinds of UV (UV-A, UV-B and UV-C). UV-A reaches the ground and causes sunburn. UV-C is absorbed in the top layer of the stratosphere, so it does not reach the ground. UV-B is strong UV; it has from 100 to 1,000 times as bad an influence upon us as the UV we usually contact. The Ozone layer blocks UV-B.

Second, what damages the ozone layer? According to the Overture humankind destruction Website, it is mainly Freon. Freon does not occur in the natural world. It was made by humans in 1928. This harmless and nonpoisonous gas was used in sprays, vending machines, air conditioners, refrigerators, and so on. Production of Freon was stopped by 1996. However, still now, it sometimes exists in old refrigerators and air conditioners. Now alternative Freon is used instead; it doesnít damage the ozone layer as much as Freon, but it has great effect on global warming.

Third, what does ozone depletion cause? I am interested in harm to health: UV-B injures DNA, and people more easily get cancer. Cataracts are also increasing. Other effects are global warming, breaking m a r i n e e c o s y s t e m s , d a m a g e o f a g r i c u l t u r e , a n d s o o n .

F i n a l l y , h o w i s t h e s t a t u s q u o a n d o u t l o o k i n t h e f u t u r e ? A c c o r d i n g t o t h e S t o p š0F r e o n n a t i o n a l c o m m u n i c a t i o n W e b s i t e , i n 2 , 0 0 0 , t h e o z o n e h o l e b e c o m e s m o r e t h a n t w i c e a s w i d e a s t h e a r e a o f Antarctic , about 70 times as wide as the area of Japan. Then Freon reaches the ozone layer in between 20 to 30 years, so there is 20 million tons of Freon which hasnít yet reached the ozone layer in our atmosphere. However, once Freon was emitted, we cannot gather it. Ozone depletion will last.

Thatís why I think ozone depletion is a very difficult problem, because there is no measure to resolve it. To summarize, human beings wonít be able to avoid the influences caused by ozone depletion by man made chemicals like Freon. However it is important to try not to emit any more Freon. For example, making good systems to withdraw any Freon which is still left in old industrial products is a good way, I think. That's all thank you. Do you have any questions?

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