Assessing Low-Cost PM and MOx Sensors for Enhanced Outdoor Air Quality Monitoring

A low-cost air quality station has been developed to investigate the use of metal-oxide sensors in outdoor air quality assessment. This study presents the results of an outdoor measurement campaign conducted in Dalmine, Northern Italy, for 67 days. The station was equipped with an optical particle counter for particulate matter (PM) measurements and metaloxide (MOx) sensors for volatile organic compounds (VOCs) detection. Measurements were compared with data from a fixed reference station operated by ARPA Lombardia. The PM sensor exhibited a strong correlation with reference values, although relative humidity influenced measurement accuracy. Additionally, MOx sensor signals demonstrated a moderate inverse correlation with PM2.5 concentration, highlighting their potential for qualitative air quality assessment. A linear regression model was applied to analyse this correlation, considering environmental factors such as absolute humidity. The results suggest that low-cost MOx sensors can complement traditional air quality monitoring systems and could be leveraged in future IoT-based environmental monitoring applications.