Benchmarking Low-Cost Particulate Matter Sensors: Evaluating Performance Under Controlled Environmental Conditions Using Low-Cost Experimental Setups

Particulate matter (PM) is widely recognized as a major air pollutant with significant impacts on human health, highlighting the need for accurate monitoring. In developing countries, low-cost sensors are crucial for accessible PM monitoring, but their accuracy and reliability must first be assessed. This study benchmarked the Alphasense OPC-N3 and Next PM sensors through laboratory and field evaluations. Laboratory tests were performed in controlled conditions with HEPA-filtered air at low humidity and varying concentrations of water droplets from nebulized deionized water. A 27-day field study in Cienfuegos, Cuba, provided additional insights into real-world performance. The OPC-N3 showed susceptibility to perturbations and was more affected by outliers (especially PM10), relative humidity, and interference from aqueous aerosols. In contrast, the Next PM sensor demonstrated superior stability, lower noise levels, and consistent performance across different environmental conditions. Despite a substantial price difference, both sensors provided valid measurements. Additionally, both sensors produced lognormal PM concentration distributions during field campaigns. This feature could aid in addressing the calibration stability challenges commonly associated with low-cost sensors through in situ calibration methods. While the PM measurements by affordable sensors are not perfect, they are sufficiently reliable for supporting air quality assessments in resource-limited settings.