The Baltimore metropolitan area, like all metropolitan areas in the United States, has experienced unprecedented growth in recent years. Such growth will be accompanied by multiplied problems of urban living. Among the continuing problems will be air pollution. Industrial emissions add to unsatisfactory levels of pollutants. The individual's automobile is part of one of the largest, most offensive groups of air pollution sources. At present, particulate pollutants are a problem. Sulfur dioxide levels have been reduced recently, but remain a potential problem. During summers, Los Angeles-type photochemical smog has appeared as indicated by hydrocarbon and oxidant levels measured. Higher nitrogen oxide and carbon monoxide levels can be expected in the future as a result of the lack of control of nitrogen oxide emissions and the anticipated increase in automobile use. Recommendations are set forth for effective control authority and regulations throughout the metropolitan area.