Under D.C. law, buses and other commercial vehicles aren’t allowed to idle for longer than 3 minutes. But according to a lawsuit filed in December by D.C. Attorney General Karl Racine, Greyhound routinely ignores the anti-idling law and allows its buses to idle at Union Station for much longer than the legal limit.

The idling pollutes the air and endangers the health of waiting passengers. Greyhound has agreed to settle the suit, paying the District $125,000 for the violations. As part of the settlement, the company will be required to change its idling policies nationwide, and conduct company-wide anti-idling training for drivers.

“Together, we will monitor Greyhound’s compliance and will take action against other companies that pollute our air, land, water, and natural resources,” Racine said in a release about the settlement.

Inspectors from the D.C. Department of Energy and Environment spent five days hanging around the Union Station bus bays in late 2018, and documented 50 Greyhound buses idling for more than the legal limit. Many were idling for longer than 20 minutes. DOEE sent 50 notices of violation to the company in early 2019, but the illegal idling didn’t stop: Inspectors documented four more instances that summer.

The settlement includes 11 requirements for how Greyhound will crack down on idling in D.C. and nationwide. The requirements also apply to BoltBus, which is owned and operated by Greyhound.

Under the agreement, Greyhound will adopt a new nationwide anti-idling policy, requiring drivers to comply with jurisdictions’ idling laws. The company will have to provide training on anti-idling to all drivers by July 31, with semi-annual refreshers after that. Locally, Greyhound will hire a full-time supervisor at Union station “whose primary responsibility is to remind bus drivers of the District’s Idling Regulation.”

Greyhound will also regularly send text messages to drivers reminding them of the District’s idling regulations (and will presumably do so without running afoul of D.C.’s anti-texting law). The company will also install stickers on bus dashboards stating that “unnecessary idling strictly prohibited.” Similar signs are already posted at each bus parking space in Union Station.

Vehicle exhaust is the biggest source of air pollution in D.C. — it causes health problems such as heart disease and asthma, and contributes to climate change. According to national estimates, idling wastes roughly 6 billion gallons of fuel and generates 60 million tons of carbon dioxide a year — equal to the annual emissions of more than 10 million cars.