Air quality is important in human daily life. It is good if we can monitor and control our environment’s air quality in real time. Therefore, this project allows users to monitor the air quality in their desired environment from a smartphone using an IoT system. The aim of the project was to monitor the environment by measuring the humidity, temperature, and air of surroundings by using low-cost sensors such as humidity sensor (DHTII), temperature sensor (LM35), and gas sensor (MQ135) which have been analyzed and studied. The project used Arduino Uno R3 and a Wi-Fi module (ESP8266) to obtain input data from sensors and the output data were displayed on a smartphone. All sensors and Wi-Fi modules were connected to the Arduino Uno R3. The Wi-Fi module was used to transmit data to the Blynk cloud and can be accessed through a smartphone via the Blynk application. The end-users can monitor the results through their Blynk application. The application showed the desired data which are the temperature, humidity, and air quality. The experiment data was collected from two places which are the city and the suburb. The collected data was taken indoors and outdoors in the two places. The results show that the air quality in the city is above 300 PPM which can be considered as high especially outdoors. It can be concluded that there are many of pollution in the city that led to a high reading of air quality.