This study examines aerosol pollution in Debrecen's various bus fleets. It draws attention to the abundance of particulate matter in the interior of both diesel and electric buses. Data was obtained using the optical particle sizer (OPS) and subsequently adjusted through a number of computations to produce useful data. Later, this data was utilised to illustrate the concentration differences between different stops in the two bus types during the spring and autumn seasons. The electric and diesel buses were compared, as well as the spring and autumn seasons.