 octane - enhancing constituents of gasoline pose a number of health hazards . 
 this paper considers the relative risks of metallic ( lead , manganese ) , aromatic ( e.g. , benzene ) , and oxygenated additives in both industrialized and developing countries . technological advances , particularly in industrialized countries , have allowed the progressive removal of lead from gasoline and the increased control of exhaust emissions . 
 the developing world , by contrast , has relatively lax environmental standards and faces serious public health problems from vehicle exhaust and the rapid increase in automobile use . 
 financial obstacles to the modernization of refineries and vehicle fleets compound this problem and the developing world continues to import large quantities of lead additives and other hazardous materials . 
 progress in decreasing environmental health problems depends both on the adoption of international public health standards as well as efforts to decrease dependence on the private automobile for urban transport.imagesfigure 1.figure 2 . 
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