A two-week-old baby in the Los Angeles area has already been exposed to more toxic air pollution than the U.S. government deems acceptable as a cancer risk over a lifetime, according to a report yesterday by an environmental campaign group...It said diesel exhaust - from trucks and cars, school buses, and farm and construction equipment - was still the worst source of air pollution. But it also took into account chemicals emitted by dry cleaners and factories as well as pesticides, adhesives and lubricant oils.