BOSTON -- Paul Revere Transportation LLC, a Boston-based bus operator, has agreed to pay a $650,000 civil penalty after being found liable by a jury of violating federal and state clean air laws.

Specifically, the company violated anti-idling laws, letting buses idle for extended periods, often for hours.

In June, following a six-day trial in U.S. District Court in Boston, a jury found Paul Revere liable for 234 separate violations of the federal Clean Air Act and Massachusetts anti-idling regulations.

A hearing to determine a penalty for the violations was scheduled for last month until the company agreed to pay the civil penalty.

Paul Revere owns and operates a large fleet of buses and other vehicles, including roughly 60 running out of its bus yard in Roxbury, Mass. In 2006, an EPA inspector observed buses idling in the yard for extended periods.

As a result, the U.S. Justice Department and Environmental Protection Agency filed a complaint against the company in federal court for violations of Massachusetts anti-idling regulations.

"This penalty appropriately punishes past violations of federal and state clean air laws and will deter other transportation companies from leaving their vehicles idling for extended periods of time in the future," said John C. Cruden, acting assistant attorney general for the Justice Department's Environment and Natural Resources Division.

The USEPA's New England office has previously brought and resolved 10 separate enforcement actions for penalties against nine different companies, including Paul Revere, for violations of the idling law.

In 2007, Peter Pan Bus Lines of Springfield, Mass., was fined more than $237,000 by the federal government for violating federal clean air and clean water rules.

Peter Pan violated Massachusetts anti-idling rules at least 45 times from February through April 2006, in and around Boston and Springfield.

Once the EPA discovered the violations at Paul Reveres Roxbury facility, inspections were conducted once a week for seven weeks. During each inspection, numerous Paul Revere vehicles, sometimes more than 20, were seen idling for periods of up to two hours. During the seven separate inspections more than 100 hours of illegal idling were witnessed.

Paul Revere's illegal idling also was documented by an individual living adjacent to Paul Revere's Roxbury yard. She testified at the trial she had witnessed violations for years at the facility.

Paul Revere had previously been cited by USEPA for violations of Massachusetts anti-idling laws. In 2003, the company paid a civil penalty for illegal idling at Boston's Logan Airport.

A spokesman for Paul Revere said the company had a strong environmental track record and was disappointed the EPA had been unwilling to settle the case.

The federal government has worked aggressively during most of this decade with the six New England states to enforce anti-idling programs. Working jointly with state and local officials, the EPA focuses its efforts on transportation facilities, particularly those in inner city neighborhoods.