Ozone is basically a secondary pollutant in the troposphere (as introduced in Chapter 2) while it is a natural constituent in the stratosphere (between heights of 15 and 50 km). This chapter mainly develops an understanding of the distinct impact the changing air pollution levels have on the resulting ozone profiles in these two atmospheric layers. In the troposphere this is associated with the alterations in the nitrogen oxide and biogenic volatile organic compounds, whereas in the stratosphere this is linked to the alterations in the chlorofluorocarbons. The later part also covers some harmful impacts of stratospheric ozone depletion on UV radiation and the state of art of the protective measures to reduce exposure.