The concentration of airborne particulate matters (PM) is related to daily hospital admissions for several pulmonary disorders such as bronchial asthma, acute and chronic bronchiolitis, and pneumonia. Especially, PM with a mass median aerodynamic diameter < or 2.5 μm (PM2.5) is recognized to be more closely associated with respiratory effects and subsequent mortality than that of mass median aerodynamic diameter < or 10 μm (PM10). However, there has been insufficient experimental evidence and their underlying mechanisms to support these epidemiological investigations. In this review, we introduce the adverse effects of PM, particularly, diesel exhaust particles, the main constituents of PM, on several pulmonary diseases, showing our in vivo evidence. Further, we also focus on the effects of nanoparticles, particles less than 100 nm in mass median aerodynamic diameter, on respiratory tract and disorders.