Diesel vehicles, as a major means of transportation, are major sources of particulate matter (PM) emissions with harmful effects on human health and environment. The light from headlights of these vehicles has a potential to cause changes in the properties of freshly emitted PM which could increase the threat posed by the PM to human health and environment. However, there is no comprehensive study available in the literature. Hence, this study investigates the potential impact of vehicle light emitted from LED headlights (found in 20–25% of new car headlight installations in 2023) on the physicochemical properties of freshly emitted PM under idle engine speed. Four PM samples were collected directly from the exhaust of a diesel vehicle and exposed to LED vehicle headlight for 0 h, 1 h, 6 h and 12 h, at a constant distance of 0.1 m. The PM samples were subsequently subjected to physical microscopy techniques and chemical analyses. In comparison with PM sample with no exposure (0 hr), it is found that vehicle light has the capability to significantly change the shapes and sizes of the PM.