The lungs of 107 of 118 youths (14-25 years of age), who died in vehicular accidents or were homicide victims, were suitable for pathologic examination, and the extent and severity of Centriacinar Region (CAR) disease was determined. f the 107 youths, 29 (27%) had severe CAR disease as judged by scores of 5 or more (on a scale of 1-10) for both severity and extent. he high incidence and severity of CAR disease in youths is unprecedented and cannot be attributed to any single agent. he pathogenesis is undoubtedly multifactorial, with socioeconomic factor dominant, in particular a suboptimal level of health care, greater impact of respiratory tract infections, high levels of air pollution, and heavy smoking and some illicit drug use. ir pollution is highly suspect for a substantial contributory role.