"The older buses produce a dirtier exhaust than the newer buses. Utilizing the retrofit reduces the number of particulates that the older exhaust systems allow to escape into the air. This means our students and others who are around the buses on a regular basis can breathe cleaner air," explained Dr. Lana J. VanderLinden, Associate Superintendent for Operations and Management Services in a news release.
A total of 15 North Carolina school districts now have biodiesel programs - including Chatham, Durham, Orange and Wake. They're taking part in an initiative started by the state legislature in 2007.
Officials say biodiesel can reduce harmful emissions by around 20 percent.
"The biodiesel creation process produces a decrease in carcinogens of particulate matter, burnt hydrocarbons and carbon monoxide, which is good for the environment and has a positive impact on public health," said Rachel Burton of Piedmont Biofuels.
Burton said that reduce pollution exposure can important for elementary school children because of their smaller size and weight.
"The typical range in which harmful particulate matter is found is around four feet high. Often young students are breathing harmful matter that adults are not because of their height," she said.