With the retirement of its last diesel buses, the Los Angeles Metropolitan Transit Authority (MTA) moved to 100% clean-fuel buses Wednesday, the first major city transit system in the nation to do so. All but a handful of the buses run on compressed natural gas (CNG).

Mayor Antonio Villaraigosa and other local and utility officials participated in ceremonies marking the milestone, 18 years after MTA purchased its first CNG-powered buses.

MTA's fleet now consists of 2,221 CNG buses, one electric bus and six gasoline-electric hybrid buses. Villaraigosa said they have logged 1 billion clean air miles. With the gathering at MTA main transportation facility near downtown Los Angeles, the officials declared that the last diesels in the 2,228-bus fleet are now history.

"Los Angeles County has become the first major transit agency in the world to operate only alternative clean-fueled buses," a spokesperson for the city and county said.

Compared with the diesel buses that the MTA retired, the CNG fleet reduces cancer-causing particulate matter by more than 80%, the spokesperson said. In addition, because of the switch from diesel to CNG, the fleet avoids emitting nearly 300,00 pounds of greenhouse gas emissions daily.

MTA Board Chair and LA County Supervisor Don Knabe said the metropolitan system has "proved from both a technical and economic standpoint" that a large transit agency can operate with alternative clean-burning fuels. Knabe said this has led a number of other transit agencies to follow the LA system's lead.

Along with Sempra utilities and other stakeholders, the American Lung Association of California CEO Jane Warner endorsed the phasing out of the diesel-fueled buses."[MTA] is helping to address the region's serious pollution problems and reduce smog-related illnesses and deaths," Warner said.

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