The term 'Layer of Concern' refers to the OZONE layer, which is a region of Earth's atmosphere that contains a high concentration of OZONE. OZONE is a gas composed of three oxygen atoms, and it absorbs most of the sun's ultraviolet radiation. The OZONE layer protects life on Earth from the harmful effects of UV radiation, such as skin cancer and cataracts. Without the OZONE layer, life on Earth would not be possible.