UV radiation from sunlight causes the reaction that produces ___.
O3
The Ozone Layer or Ozone Shield is a region of Earth's stratosphere that absorbs the most of the sun's ultraviolet radiation. It contains high concentrations of ozone gas (O3). The photochemical mechanisms that give rise to the ozone layer in Earth's stratosphere is created by ultraviolet light striking ordinary oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create ozone, O3.