BOSTON — Boston Public Schools will operate 11% of its total school bus fleet on propane starting in September, officials announced last week.

The district purchased 86 Blue Bird propane autogas buses this month, and district officials said that they hope to convert more of the diesel fleet to propane buses in the future.

“These new Blue Bird Propane Visions mean many students will no longer be exposed to diesel fumes when boarding or disembarking our buses,” said Peter Crossan, fleet manager for Boston Public Schools’ transportation department.

Like many urban cities, Boston has enacted mandates for reducing tailpipe emissions. The school district, which is the city’s largest user of diesel fuel, has implemented a number of emissions-reducing initiatives in the past 15 years through its “Greening Boston Public Schools” program.

“The propane bus purchase fits with our mission to choose vehicles with the highest efficiency and the lowest environmental emissions," Crossan said.

The new buses are powered by a Ford V10 engine and a ROUSH CleanTech propane autogas fuel system. According to Blue Bird, Boston Public Schools’ propane fleet will emit 66,000 fewer pounds of nitrogen oxide and 2,700 fewer pounds of particulate matter each year compared to the diesel buses they are replacing.

Boston Public Schools started exploring alternative fuels once the city’s outdated tunnel restrictions were lifted.

About 40% of the district’s fleet consists of 169-inch wheelbase buses. Officials said that this smaller bus size meets the district’s needs for range and hours of service, and it works well for Boston’s urban routes and special-needs applications.

“We designed and engineered a propane autogas fuel system on the short wheelbase buses to meet Boston Public Schools’ operating needs,” said Phil Horlock, president and CEO of Blue Bird.

The 169-inch wheelbase bus is designed with a 50-gallon tank to accommodate shorter runs. This new offering expands Blue Bird’s propane autogas portfolio, which also includes 70-gallon standard and 100-gallon extended-range propane tanks.

Boston Public Schools expects savings of at least $1 per gallon on fuel and lower maintenance costs due to the cleaner burning properties of propane autogas, officials said.

To fuel the buses, the district has contracted with a company that performs on-site propane autogas fleet fueling services.

“We want other school districts to know that on-site infrastructure isn’t the only option when introducing propane autogas into their fleet,” Crossan said.

Boston Public Schools will take delivery of the buses in June.