This study aimed to investigate the association between DEPs (diesel exhaust particulate matter) exposure and emphysematous lung. There were three buses used as diesel particulate matter sources. DEPs were classified into ultrafine, fine, and coarse particles with different aerodynamic diameters. This study used mice that were divided into control and treatment groups. The treated mice were exposed to the DEPs in different concentrations (low, mid, and high doses) for eight consecutive days. The control group did not receive any exposure treatment, while the exposed mice were sacrificed on the ninth day to get the lung samples. The lung samples were observed under a digital microscope to identify the normal and deformed alveolar cells. According to the observation results, the emphysematous level increased linearly to the DEPs dose concentration. The emphysematous level was found in the range of 64-80%, depending on the exposure dose concentration. In summary, direct exposure to the DEPs was correlated to the emphysematous level. This study has given a novel explanation of the bus exhaust emission risk as a heavy-duty vehicle in organs, especially due to the ultrafine, fine, and coarse particles exposures.