Gasoline and diesel vehicles are one of the main sources of PMs generation which are harmful to human health and the environment. The light emitted from the headlights of these vehicles may cause to make the PMs more/less/not dangerous than the raw PMs to human health and the environment by changing their properties. However, there is no information available in this field. Therefore, this research is presented to investigate the effect of light emitted from one of the most common vehicle headlights (Halogen type) on the physical properties of PMs. Three PM samples taken directly from one diesel vehicle operating at an idle condition, and inside of a diesel particulate filter and gasoline vehicle exhaust pipe (engine was off) were exposed to the vehicle headlight for 6 hrs at 10 cm distance. It is observed that the vehicle light has the potential to change the structure, shape, and size of the PMs, while the fresh PMs from diesel vehicle receives more changes (43.5% increase in particle diameter) compared with the other two samples containing mature/aged PMs (increases of 3.6 and 9.9%, respectively). Also, the effect of the beam from the scanning electron microscope on the PM physical properties is presented.