Ozone layer depletion

Ozone hole, Ozone depletion

1. THE OZONE LAYER DEPLETION 1 Name- ANKIT SARKAR Roll Number- 16501313003 Department of Civil Engineering C.I.E.M Under the guidance of Prof. Mrinal K Ghose

2. INTRODUCTION Ozone is a form of oxygen (O3), Most of the atmospheric ozone occurs in the stratosphere region, the greatest concentration of ozone occurs between 19-30km. This band of ozone rich air is called ‘Ozone-Layer’. Ozone is both beneficial and harmful to us but the depletion of ozone layer is very much harmful to the environment and habitats. 2

3. LAYERS OF THE ATMOSPHERE The atmosphere is divided into six layers. It is thickest near the surface and thins out with height until it eventually merges with space. 1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. 2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun. 3) Meteors or rock fragments burn up in the mesosphere. 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits. 3

4. 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere. 6) The ionosphere overlaps the other atmospheric layers. The air is ionized by the Sun’s UV light. These ionized layers affect the transmittance of radio waves. 4 Ozone layer

5. THE SUN’S ULTRAVIOLET RAYS The sun emits energy over a broad spectrum of wavelengths: visible light that we see infrared radiation that you feel as heat ultraviolet (UV) radiation that we can’t see or feel. UV radiation has a shorter wavelength and higher energy than visible light. 5

6. ADVANTAGES & DISADVANTAGES OF UV RAYS:- Fortunately for life on Earth, our atmosphere’s stratospheric ozone layer shields us from most UV radiation. It affects human health both positively and negatively. Short exposure to UVB radiation generates vitamin D, Sterilization, Pest Control, Authentication of documents. High exposure of UVB radiation can causes skin diseases, even skin cancer. 6

7. THE OZONE LAYER The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it. The layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun. For nearly a billion years, ozone molecules in the atmosphere have protected life on Earth from the effects of ultraviolet rays.   7

8. THE OZONE LAYER DEPLETION 8

9. THE OZONE HOLE AND ITS CAUSES Recently, chlorofluorocarbons (CFCs) were used a lot in industry and elsewhere to keep things cold and to make foam and soaps. Strong winds carry CFCs up into the stratosphere where UV radiation breaks them apart, releasing chlorine atoms. Each chlorine atom can attack and break apart (destroy) as many as 100,000 ozone molecules during the time it is in the stratosphere. 9

10. The chlorine from CFCs reduces (depletes) the amount of ozone in the stratosphere. Other ozone-eating chemicals are pesticides such as methyl bromide, halons used in fire extinguishers, and methyl chloroform used in businesses. 10

11. Damage to the ozone layer can cause the following: Skin cancer Cataracts Suppression of the immune system Premature aging of the skin Since the benefits of sunlight cannot be separated from its damaging effects, it is important to understand the risks of overexposure, and take simple precautions to protect yourself. 11 10% depletion in ozone results in 30% increase of skin cancer

12. OBSERVATIONS ON OZONE LAYER DEPLETION There are many observations on the ozone layer. The following are a few observations: 12

13. OBSERVATION 1 Scientists did predict that ozone depletion should peak around year 2010. As world-wide controls reduce the release of CFCs and other ozone-eating substances, nature will repair the ozone layer. By year 2065 stratospheric ozone should return to the amount present in 1980. Until then, we can expect higher levels of UV radiation at the Earth's surface. We need to take care to avoid the bad health effects that could result from too much UV radiation. 13

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15. OBSERVATION 2 Most countries have seen the threats created by ozone depletion and agreed to a treaty called the Montreal Protocol. This Protocol will help humans to stop making and using ozone-eating chemicals. 15

16. MISCONCEPTIONS ABOUT THE OZONE LAYER DEPLETION 16 COMMON MISTAKE FACT Global warming is caused by the ozone hole which was created by chemicals like CFC etc. The ozone layer protects the Earth from the Sun’s harmful UV rays. Hole in the ozone layer has been caused by chemicals released by humans. CFC’s are “too heavy” to reach the stratosphere. CFC’s are commonly believed to be heavy. But atmosphere gases are not sorted by weight. The wind mixes the gases and they reach the atmosphere.

17. PROTECTING THE OZONE LAYER The ozone layer must be protected. For this the use of CFC’s has to be stopped. We must buy products that are labeled “ozone friendly” or “ CFC free”. Substitutes for CFC’s should be used. HCFC’s are substitutes for CFC’s. Let us all take a step ahead and save the ozone layer. 17

18. 18 CONCLUSION Ozone is both beneficial and harmful to us. Ozone Depletion can cause a variety of health problems in humans. So its our duty to protect the ozone layer. Some international conventions like Vienna Convention and Montreal Protocol are of greatest success stories. The Climate of Antarctica has changed a lot for Ozone depletion, future will reflect both ozone recovery and GHG warming.

19. 19 REFERENCES http://en.wikipedia.org/wiki/Ozone_depletion http:// www.epa.gov/sunwise/doc/uvradiation.html http://www.unep.org / http ://ozone.unep.org/en/treaties-and-decisions/montreal-protocol-substances-deplete-ozone-layer TIDEE Journal- Depletion of Ozone Layer by Mrinal K Ghose

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