The 40 - foot, near - zero - emission, diesel - electric hybrid buses cost more to purchase but less to operate and are cleaner and quieter than traditional diesel buses. (transportation.gov)
Since the Columbia team started tracking air pollution levels in 1998, PAHs have declined, which Perera attributes to stricter anti-idling laws and phaseout of older diesel buses in New York City. (scientificamerican.com)
Although there are no available stats on diesel buses in the database we were using, we grabbed data for a 9.3 tonne diesel truck and scaled it to a bus to make it more or less the same. (treehugger.com)