Björn Sunström at the Technical Research Institute says new bus models are more prone to fires.
"The engine compartments are isolated for sound to quiet them down. And when one isolates sound, heat is isolated as well, creating a fire hazard," Sundström tells Swedish Radio News.
Some of Sweden's public buses are equipped with extinguishing systems that put out fires automatically using water or a chemical powder. Björn Sundström believes that if such a system works as intended, it can be an effective means of preventing bus fires.