Validation of Low-Cost Sensors in Measuring Real-Time PM Concentrations at Two Sites in Delhi National Capital Region.

In the present study, we assessed for the first time the performance of our custom-designed low-cost Particulate Matter (PM) monitoring devices (Atmos) in measuring PM concentrations. We examined the ambient PM levels during an intense measurement campaign at two sites in the Delhi National Capital Region (NCR), India. In this study, we validated the un-calibrated Atmos for measuring ambient PM concentrations at highly polluted monitoring sites. PM concentration from Atmos, containing laser scattering-based Plantower PM sensor, was comparable with that measured from research-grade scanning mobility particle sizers (SMPS) in combination with optical particle sizers (OPS) and aerodynamic particle sizers (APS). The un-calibrated sensors often provided accurate PM measurements, particularly in capturing real-time hourly concentrations variations. Quantile-Quantile plots (QQ-plots) for data collected during the selected deployment period showed positively skewed PM datasets. Strong Spearman's rank-order correlations ( = 0.64-0.83) between the studied instruments indicated the utility of low-cost Plantower PM sensors in measuring PM in the real-world context. Additionally, the heat map for weekly datasets demonstrated high values, establishing the efficacy of PM sensor in PM measurement in highly polluted environmental conditions.