Comparing Performance and Reliability of Collocated Enhanced Children's MicroPEM (ECM) on Gravimetric and Nephelometric PM2.5 Personal Exposure Samples in Field Measurements in Rural Guatemala.

Traditional gravimetric instruments used for personal air pollution exposure measurements are often cumbersome and noisy and do not offer real‐time assessment capability. The Enhanced Children's MicroPEM (ECM) is a comparatively lightweight and quiet instrument designed to capture both integrated filter‐based gravimetric samples and real‐time continuous (nephelometric) particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) concentrations. We assessed the performance and reliability of collocated ECMs in a subset of pregnant women participating in a randomized controlled trial in Guatemala to test a liquefied petroleum gas (LPG) cookstove (intervention) versus biomass (control) for cooking. We compared average daily (24 h) PM2.5 concentrations for the paired gravimetric (n = 219) and paired adjusted nephelometric (n = 221) samples using Spearman correlation and Bland–Altman agreement; we also assessed reliability based on the intraclass correlation coefficient (ICC) and root mean square error (RMSE). Median PM2.5 gravimetric concentrations were 93.5 μg/m3 (interquartile range (IQR) = 52.6–160.5) and 21.4 μg/m3 (IQR = 12.0–32.0) in the control and LPG intervention groups, respectively; the median adjusted nephelometric concentrations were 83.7 μg/m3 (IQR = 47.6–148.9) and 22.6 μg/m3 (IQR = 17.5–29.7) in the control and LPG groups, respectively. Spearman correlations were higher in the control arm (0.91) than in the LPG intervention arm (0.67) in the gravimetric comparisons. The same trend was observed for adjusted nephelometric measurements in the control (0.92) and intervention arms (0.75). ICC values were high in both gravimetric (0.93) and nephelometric (0.95) collocations. Small differences in RMSE were observed for the gravimetric (26.69 μg/m3) and nephelometric collocations (31.76 μg/m3). Our findings demonstrate strong reliability between collocated ECMs for both gravimetric and adjusted nephelometric PM2.5 personal exposure samples in rural Guatemala. Trial Registration: ClinicalTrials.gov identifier: NCT02944682 [ABSTRACT FROM AUTHOR]