The ozone hole is a region of depleted ozone layer in the Earth's stratosphere, specifically over the polar regions. The ozone layer is a protective layer of gas in the atmosphere that shields the Earth from the harmful ultraviolet rays of the sun. The depletion of the ozone layer, particularly over the Antarctic region, was first discovered in the 1980s and is primarily caused by human-made chemicals such as chlorofluorocarbons (CFCs) which were commonly used in refrigerants, aerosols, and solvents. The hole in the ozone layer allows more harmful UV radiation to reach the Earth's surface, which can cause health problems in humans and animals and damage to ecosystems.