Outdoor air pollution is a serious worldwide problem, affecting millions of people, with serious consequences for public health, economy and for social issues. Internet of Things (IoT) has emerged as a response to the creation of intelligent monitoring systems that can be used for management and identification of pollution sources, and for health protection. With the development of new devices and technologies that allow the creation of real-time monitoring applications, this reality has become increasingly relevant nowadays. This paper aims to introduce an implementation of an IoT system for outdoor air quality monitoring, based on multichannel smart sensing system with LoRa communication capability. The system incorporates low cost and low consumption sensors capable of detecting different air pollutants, as well as temperature and humidity. To achieve a long-distance transmission of readings with low energy consumption, the use of LoRa technology was adopted due to its characteristics. The periodicity of sending readings to the network is based on the level of urban traffic in a certain location. Furthermore, a web application is presented, which allows the user to monitor in real time and to carry out a temporal analysis of the measurements taken by the system.