David Peat

174 From Certainty to UncertaintyAt the time Freon appeared perfectly harmless. It didn’t corrode,and if some of the gas did escape it had no odor to contaminate food,while its chemical inertness did not present a fire or health hazard. Itwas only decades later that chemists began to suspect that chlorofluorocarbonsmight affect the ozone layer. As a result of the sun’s actionon the upper atmosphere, three oxygen atoms combine to form a singlemolecule of ozone. Ozone is of critical importance to life on earthbecause it acts as a sunshade over the earth and filters out the sun’sharmful ultraviolet rays. But sunlight also breaks down Freon moleculesin the upper atmosphere and releases chlorine, which then attacksozone molecules.It was only with the advent of space probes that scientists discoveredhow disastrous Freon’s effects had been over the last decades. Allthe Freon from aerosol cans, discarded refrigerators, and air conditionershad collected in the upper atmosphere where it was attackingozone. As a result, it had created a large hole in that part of the ozonelayer that lies over the South Pole, and a smaller hole over the NorthPole. If this depletion had continued unchecked—and ozone is stillunder attack from residual chlorofluorocarbons in the upper atmosphere—itwould have endangered all life on earth, increasing the rateof skin cancers and promoting genetic damage.LeadIn the first chapter we listed the automobile as one of the key factors inshaping our modern world. The availability of cheap and rapid transporttransformed society and enabled people to work in cities andcommute to suburbs. Indeed, the suburb itself, along with the highwayand drive-in were all spin-offs of the automobile. What’s more, thedemand for ever more gasoline has transformed global politics by increasingthe strategic importance of oil-producing nations. The automobileis also the major cause of death among young people. MoreAmericans have been killed in automobile accidents than have died inall the wars the United States has fought since independence.The impact of the automobile on society demands a book in itself.But just take one related issue, the attempt to make engines more effi-