Clean Bay Area Diesel BusSan Francisco area residents can breathe cleaner air in the years ahead, as the Metropolitan Transportation Commission (MTC) nears completion of a historic program to clean up the exhaust from more than 1,700 diesel buses. Through the Clean Diesel Bus Program, the city buses from 13 Bay Area transit districts are being retrofitted with diesel exhaust filters…

All together these high-tech emission control filters annually capture more than 50 tons of harmful particulate matter and 436 tons of oxides of nitrogen (NOx) that, if released into the air, would cause lung disease, cancer and respiratory ailments.


Installation of the pollution-control devices began in 2003 and already 1,400 exhaust filters for Bay Area buses have been delivered. Most of the remaining 340 exhaust filters are scheduled for installation by the end of 2006.

While the 13 Bay Area transit districts participating in the bus retrofit have purchased some clean new buses, most of the exhaust reduction is coming from the installation of emission filters on existing buses that have years of life remaining. Each installation costs about $18,000, compared to $140,000 or more for a new bus.

Without having to buy new buses, "retrofitting buses is a cost-effective way to clean the air," explained Steve Heminger, executive director of MTC. "The installation of the exhaust filters goes a long way," because the devices capture 85 percent of the particulate matter created by the older buses’ engines while reducing exhaust that contributes to smog by 25 percent.

On an average Bay Area bus, each diesel exhaust filter reduces particulate matter emissions by 59 pounds per year and reduces NOx emissions by 515 pounds per year. (details at MTC)

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