Fox 11 News went to the Tucson Unified District Transportation Department to get some answers after they captured one particular bus belching out excessive amounts of pollution and smoke during its regular rounds.

Fox 11 News followed bus number 184, which is 20 years old, for about ten minutes.

Alex Bendyna works with the Tucson Unified School District Transportation Department and says he hates smoking vehicles.

Bendyna said the driver of bus 184 was aware that Fox 11 News was following him and also knew the reason why.

After Fox 11 showed Bendyna the video of the bus, he said someone had put too much oil in the bus engine. The black smoke released into the air is oil being burned off.

Beth Gorman, Program Manager for Pima County Department of Environmental Quality, said motor vehicles cause about 60% of the air pollution in Pima County.

She reported that from January 1, 2006 to February 19 of this year there have been over 1,800 smoking vehicles reported. Thirteen of these reports involved TUSD busses. Some of these buses had even been reported twice.

Fox 11 News once again followed bus 184 a day after speaking to Bendyna and the smoke was gone. He said the buses use ultra low sulfur diesel.

Bendyna also said TUSD is in the process of acquiring new buses to replace these older ones.

All buses are required to test for emissions and maintenance at least once a year.