An Antarctic ozone hole forms from September to November each year, caused by man made pollutants that destroy ozone in the atmosphere. The hole has been getting progressively larger. The culprits are chlorofluorocarbons (CFCs), once used as coolants. The ozone hole above Antarctica starts forming in September, when springtime sunlight returns to the polar skies. The light energizes chlorine and bromine containing chemicals that break down ozone molecules in the stratosphere and destroy it. Sunlight splits off chlorine from CFCs, and the chlorine ozone reaction takes place most readily on the surface of ice crystals (Onion). Polar Regions reflects the greatest changes in ozone concentrations, especially the South Pole.