The ozone hole was first discovered in Antarctica in 1985 by British scientists. It is a region of Earth’s stratosphere that absorbs most of the Sun’s ultraviolet radiation. The ozone layer contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth’s atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 20 to 30 kilometers (12 to 19 mi) above Earth, although its thickness varies seasonally and geographically.
The ozone hole was caused by human activities, primarily the release of chlorofluorocarbons (CFCs) into the atmosphere. CFCs are chemicals that were once widely used in refrigerators, air conditioners, and aerosol cans. When CFCs reach the stratosphere, they are broken down by ultraviolet radiation and release chlorine atoms. These chlorine atoms react with ozone molecules, destroying them.
The ozone hole has a significant impact on the environment. It allows more ultraviolet radiation to reach Earth’s surface, which can cause skin cancer, cataracts, and other health problems. It can also damage plants and animals.
The Montreal Protocol, an international treaty, was signed in 1987 to phase out the production and use of CFCs. As a result of the Montreal Protocol, the ozone hole is slowly recovering. However, it is expected to take decades for the ozone layer to fully recover.
The correct answer is: B. Antarctica