Federal regulators should crack down on pollution from power plants and factories and not put so much of the burden on cars, says AAA, the motorists’ advocacy group. The group is releasing a study today that found that pollution from automobiles has declined much more rapidly over the past 30 years than pollution from other sources. However, Paul Billings of the American Lung Association argues that pollution reductions are needed wherever they are available. Billings: “As long as the number of miles traveled continues to increase, each incremental decrease from cars makes a difference because there are so many cars on the road.”