Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFC = s react with sunlight in the earth’s stratosphere to break down the protective ozone layer, a layer of gas that shields the earth’s surface from damaging UV-B rays