1. UNIT 3.5 OZONE DEPLETION IGCSE Y7 SCIENCE Prepared by Ms Wong

2. What is OZONE? ■It is a GAS ■There is a layer of OZONE high up in the atmosphere ■Ozone absorbs UV rays from Sun IGCSE Y7 SCIENCE Prepared by Ms Wong

3. What is OZONE? IGCSE Y7 SCIENCE Prepared by Ms Wong

4. What is OZONE? Ozone protects organisms on Earth from harmful UV radiation. Without Ozone layer, more UV light would reach the ground IGCSE Y7 SCIENCE Prepared by Ms Wong

5. Questions 1. Where is the ozone layer? In the atmosphere, about 25 km above the ground. They can cause skin cancer and damage the eyes. 2. Describe how ultraviolet rays can harm a person. 3. How does the ozone layer protect us? The ozone layer absorbs ultraviolet rays from the Sun, so less of them reach the Earth’s surface IGCSE Y7 SCIENCE Prepared by Ms Wong

6. Big Ozone holes for Extinction by 2040 ■Ozone hole is not really a hole but only an area where there is less ozone than normal. ■Each year, NASA measure the changes and it has been getting larger every year. IGCSE Y7 SCIENCE Prepared by Ms Wong

7. Big Ozone holes for Extinction by 2040 IGCSE Y7 SCIENCE Prepared by Ms Wong

8. WHAT CAUSES THE OZONE HOLE? IGCSE Y7 SCIENCE Prepared by Ms Wong

9. Hypothesis that anthropogenic CFC have depleted O 3 suggested in 1974. Immediately controversial!! Everyday products had CFCs Propellants in spray cans Refrigerants Cleaning agents Styrofoam IGCSE Y7 SCIENCE Prepared by Ms Wong

10. CFC LAST FOR A VERY LONG TIME How long? About 100 years in the atmosphere IGCSE Y7 SCIENCE Prepared by Ms Wong

11. IGCSE Y7 SCIENCE Prepared by Ms Wong

12. Questions 4. What are CFCs? CFCs are gases that were used in air conditioners, refrigerators and aerosol cans. (CFC is short for chloro-fluorocarbon.) 5. Explain how CFCs harm the ozone layer. CFCs break down ozone, therefore thinning the ozone layer. IGCSE Y7 SCIENCE Prepared by Ms Wong

13. Summary ■Ozone is a gas found in a layer high up in the atmosphere. ■The ozone layer protects us from ultraviolet radiation. ■CFCs have damaged the ozone layer over the Antarctic. ■CFCs are now banned and the ozone layer is recovering. IGCSE Y7 SCIENCE Prepared by Ms Wong