Urbanization is occurring at an alarming rate, causing severe pollution events in different developing cities. Delhi is one among them, and it experiences frequent air pollution episodes. Most of the time, the concentration of the pollutants is found beyond the prescribed limits. This study measured and analysed the traffic-induced nanoparticle concentration in the roadside micro-environment. Two periods were considered for the study: Period I, which had less emissions (April–June 2021), and Period II which experienced increased emissions (October–November 2021). During Period I, due to vehicle restrictions, the concentration measured was 31% less than that under normal conditions, and in Period II, due to the high emissions the concentrations were around 35% more than usual. During Period I, the mean concentration of the particles ranged from 103 to 105 cm−3 particles, and during higher emissions, the concentration increased up to 104 to 105 cm−3. The results obtained through different emission scenarios in the atmosphere will help us better understand the connection between vehicle emissions and contaminants, especially in the microenvironment around metropolitan roadway.