The term 'Endangered Atmospheric Layer' refers to the OZONE layer, which is a layer of gas in the Earth's atmosphere that protects us from the sun's ultraviolet radiation. The OZONE layer is being depleted due to human activities such as the release of chlorofluorocarbons (CFCs) into the atmosphere. This depletion has caused an increase in the amount of UV radiation reaching the Earth's surface, leading to an increase in skin cancer and other health problems.