Abstract: In this communication, a comparison between a home-developed low-cost system and reference methods for air quality measurement is performed. For the measurement of the main pollutants, both gaseous (NO ₂ , NO, O ₃ , CO) and particulate matter (PM10 and PM2.5), electrochemical and optical sensors are used, respectively, all from Alphasense brand. In addition, it has been included the sensing of meteorological data that could affect the measurement of pollutants (temperature and humidity). All data collected is stored on an external flash memory connected to the device (microSD). In addition, it is possible to transmit the data in real time using Ethernet, GSM or LoRA. Finally, it incorporates Bluetooth communication in order to communicate with a nearby smart mobile device. The control core of the system is a low power microcontroller from the manufacturer ST (STM32L476). The entire system is powered by a 230 V AC power supply. The equipment includes a pump for air sampling (active sampling). Reference equipment has been used to perform correlation tasks and preliminary calibrations. This equipment belongs to the air quality protection and research network of Extremadura. The complete system has been tested in real conditions during two months together with the fixed reference stations located in Badajoz and Plasencia (Spain). Its general operation has been positive, with strongly correlated results, although the calibration of the electrochemical sensors should be modified in future work to improve their performance, especially in low-pollution environments.

Keywords: Air quality monitoring, Electrochemical sensors, Particulate matter, Low-cost.

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