Sustained Performance of Low-Cost Air Quality Sensors in Long-Term Deployments

Over the past decade, technological advancements and the growing demand for higher spatial resolution in air quality measurements have driven the widespread deployment of low-cost electrochemical gas sensors. These sensors are inexpensive, compact, easy to deploy, and have potential to detect variability in ambient air. While short-term sensor performance and calibration assessments have been well-documented, research on sensor reliability in long-term deployments remains limited. The Berkeley Environmental Air Quality and CO₂ Network (BEACO₂N) is a dense, long-term sensor network measuring O₃, NO, NO₂, and CO using electrochemical gas sensors, in addition to CO₂ and PM_2.5 with other sensors. Here, we evaluate the performance of the Alphasense NO2-B43F, Ox-B431, NO-B4, and CO-B4 sensors over the course of 3 years in the San Francisco Bay Area. We find consistent performance in the calibrated data over the 3 years. These findings highlight the reliability of long-term sensor use with appropriate calibration techniques and suggest the sensors remain suitable for extended deployments without requiring replacement.