In Indonesia, the number of motorized vehicles has increased from year to year. These vehicles are considered as the main source of air pollution, because it produces carbon monoxide (CO), sulfur dioxide (SO2), and other substances. Exposure to this pollution can have an adverse health effects, even death. This study has developed an air pollution monitoring system based on Internet of Things (IoT) technology, especially for CO and SO2 gases. This system involves CO-B4 and SO2-BF electrochemical gas sensors, ESP8266 NodeMCU development board, and the Blynk application on smartphone. The experimental results show that the sensor response tends to be linear to the gas concentration. This system is able to display the location and concentration of gas in real-time for open field applications. Based on measurements show that there is a low gas concentration in the morning. Significant increases in gas concentrations occurred around 07.00 o'clock, i.e. 31.84 ppm and 5.37 ppm for CO and SO2, respectively. Exposure to high gas concentrations appears to be maintained during the day as a busy traffic. A significant increase in gas concentration also occurred around 17.00 o'clock, i.e. 35.69 ppm and 5.27 ppm, for CO and SO2, respectively.