摘要：Population growth and the proliferation of roadways in Southern California have facilitated a glut of mobile air pollution sources (cars and trucks), resulting in substantial atmospheric pollution. Despite successful efforts over the past 40 years to reduce pollution, an alarming set of health effects attributable to air pollution have been described in Southern California. The Children’s Health Study indicates that reduced lung function growth, increased school absences, asthma exacerbation, and new-onset asthma are occurring at current levels of air pollution, with sizable economic consequences. We describe these findings and urge a more aggressive effort to reduce air pollution exposures to protect our children’s health. Lessons from this “case study” have national implications. ROADWAYS ARE AN IMPORTANT feature of the built environment in the United States, one that has developed as a result of massive investment and of public policy heavily influenced by private interests. Los Angeles once had a model public transit system based on an extensive and efficient network of electric trolleys. This system, along with the streetcar systems in 45 other cities, was bought and dismantled in the 1930s by National City Lines, a holding company owned by corporate partners in the automotive industry. 1 In Los Angeles alone, the people who made 280 million passenger trips a year on the mass transit system were forced into other forms of transportation. The automobile controlled the future of Los Angeles. Today, a large proportion of the US population lives in heavily populated “mega-cities,” such as the greater Los Angeles region, and depends on automobiles for transportation and diesel trucks and trains for transporting goods. Truck and automobile emissions are responsible for most of the air pollution in Southern California, with significant additional mobile source contributions from airports and the nation’s largest marine port complex. In Southern California, episodic outdoor levels of ozone (O3), particulate matter less than 10 microns in diameter (PM10), and nitrogen dioxide (NO2) historically have been among the highest in the United States, and they continue to exceed federal and state clean air guidelines. 2, 3 Research conducted in the 1970s and 1980s confirmed acute effects of exposure to ozone and other traffic-related pollutants. 4, 5 However, until recently, long-term health consequences were more uncertain, particularly among children, a population with rapidly growing lungs likely to be sensitive to the effects of air pollution.
