Due to the presence of toxic gases like nitrogen oxides, carbon monoxides and other polluting compounds in vehicular emissions, urban air pollution is very prevalent. For this purpose, this paper aimed in detecting the level of air quality in three busy roads in Metro Manila- Stop N Shop, V. Mapa, and Cubao. The ambient measurement was done in a near-road manner using Arduino ATmega328 Microcontroller and MQ-135 gas sensor which is sensitive to smoke, NH3, NOx, alcohol, Benzene, CO2 and other gases. From the measured data, air quality was assessed on each area based on the standard air quality index. The traffic density and specific predominant type of vehicle for the selected areas were found to have an effect in the measurements. Results show that Stop n Shop have a higher concentration of gas in ppm as detected by the system than other concerned areas.