Evaluation and Calibration of Clarity Node S Low-Cost Sensors in Lubbock, Texas

Abstract. Aerosol particles, also known as Particulate Matter (PM), have a profound impact on human health, air quality, the weather, and climate. PM can be measured using a variety of measuring techniques and instruments, notably reference-grade instruments and Low-Cost Sensors (LCS). Although Low-Cost Sensors allow for a higher resolution network, some have accuracy issues and reliability when compared to reference-grade units, which prompts the need to develop a calibration. This work, which is part of the Lubbock Environmental Action Plan (LEAP) for Communities, aims to provide information on air quality levels across the city of Lubbock using Clarity Node S sensors. In this study, which is the first step of the work, an evaluation and calibration of four Clarity Node S sensors was performed. The Clarity Node S sensors were selected for this project due to the sensors' ability to operate without a power or Wi-Fi source. Good agreement was found between the sensors when they were collocated with each other from March to May 2024 on the Aerosol Research Observation Station (AEROS). Next, one LEAP unit was collocated at AEROS with a reference unit, and different calibration tests were performed for the three PM concentrations measured by the Clarity units (PM₁, PM_2.5, and PM_10, particles with diameters <1, 2.5, and 10 µm, respectively). The selected calibration was developed and implemented for all four LEAP units. The calibrated LEAP units were then collocated near two different reference units for a duration of eight months (July 2024 to February 2025), and a comparison was performed. While one reference unit showed a good agreement with three LEAP units, the other reference units were very different from the collected LEAP unit.