A new independent study demonstrates that increasing public transportation use is the most effective way to improve air quality and reduce energy consumption without imposing new taxes, government mandates or regulations. The study, "Conserving Energy and Preserving the Environment: The Role of Public Transportation," released Wednesday, concludes that public transportation generates 95% less carbon monoxide (CO), 92% less in volatile organic compounds (VOCs) and about half as much carbon dioxide (CO2) and nitrogen oxide (NOx) per passenger mile as private vehicles. The study, conducted by three top economists, shows that public transportation already saves more than 855 million gallons of gasoline or 45 million barrels of oil a year. The study also shows that if one in 10 Americans used public transportation regularly, U.S. reliance on foreign oil could be cut by more than 40%. In addition, carbon dioxide emissions would be reduced by more than 25% of the standard set under the Kyoto agreement. Among the study's other major findings:

• Even small increases in transit usage would help many of the 16 major U.S. cities, which currently fail to meet EPA air-quality standards for CO or smog, improve air quality.

• For every passenger mile traveled, public transportation is twice as fuel efficient as priate automobiles, sports utility vehicles and light trucks.