The correct answer is True.
The ozone hole is a thinning of the ozone layer in Earth’s stratosphere over the Antarctic that occurs annually from October to mid-February. 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 absorbs most of the Sun’s ultraviolet radiation, which is harmful to the biosphere. The thickness of the ozone layer is measured in Dobson units (DU). One Dobson unit is equivalent to 2.68 x 10^16 molecules of ozone per square centimeter.
The ozone hole was first observed in the late 1970s and early 1980s. The main cause of the ozone hole is the release of chlorofluorocarbons (CFCs) into the atmosphere. CFCs are man-made chemicals that were once widely used in refrigerants, aerosol propellants, and foam-blowing agents. CFCs are stable in the lower atmosphere, but they break down in the stratosphere, releasing chlorine atoms. Chlorine atoms react with ozone molecules, destroying them.
The Montreal Protocol, an international treaty signed in 1987, phased out the production and use of CFCs. As a result of the Montreal Protocol, the ozone hole has been slowly shrinking. However, the ozone hole is still present and can still cause harm to human health and the environment.
The horizontal extent of the ozone hole can sometimes exceed the size of the Antarctic continent. In 2019, the ozone hole reached a record size of 24.8 million square kilometers. This is larger than the area of the United States, Canada, and Mexico combined.
The ozone hole is a serious problem that can have a significant impact on human health and the environment. It is important to take steps to protect ourselves from the harmful effects of ultraviolet radiation, such as wearing sunscreen and sunglasses, and to reduce our exposure to CFCs.