Harnessing the Clean Air Act to Manage Metropolitan Growth

In the forty years since the passage of the original Clean Air Act, urban air quality has improved significantly in the United States. Less than a century ago, the vast quantity of coal smoke emitted by urban industries was sufficiently great to obscure the sun, often requiring street lamps in the largest industrial cities to remain lighted throughout the day. Urban residents waged a losing battle against the pervasive dust and ash that entered the home, while downtown merchants labored to keep their merchandise free of soot. More than an aesthetic nuisance, the thick air pollution was directly tied to a range of respiratory illnesses and was believed by civic and religious leaders to be at the root of a societal deterioration in morality (Boyer 1978). Perhaps the most lasting implication of industrial air pollution, however, was its influence on urban development patterns. “Smoke suppressed property values, as clean air became a selling point in the suburbs and dirty air became a reason to flee neighborhoods near city centers” (Stradling 1999, 30). It is perhaps ironic that a century of urban decentralization has not succeeded in providing clean air for the majority of Americans. Many modern air quality problems have tagged along for the ride to the suburbs, undergoing a transformation from the localized stack emission to the regionalized by-products of vehicle travel, such as ground-level ozone and greenhouse gases. Despite the substantial success of the Clean Air Act in reducing stack and tailpipe emissions through technological controls, 58 percent of the U.S. population resides in regions in which air pollution still exceeds national health-based standards (U.S. Environmental Protection Agency [EPA] 2001b, 10). It is estimated that between fifty and sixty thousand Americans die prematurely each year from air pollution–induced cardiopulmonary diseases, a fatality rate surpassing that of auto-related deaths in most large cities (Shprentz 1996, 1). The persistence of urban air quality problems in the United States may be attributed, in part, to the nature of control strategies that have been employed to combat mobile source air pollution. The predominant approach to achieving air quality standards over the past thirty years has been through the mandated development of increasingly effective emissions control technologies. While this approach has been highly effective in reducing emissions of vehicle pollutants per mile of travel, an increase in the number of vehicles owned and the number of miles driven per capita