Air pollution exposures pose the greatest health risk to global communities, with the majority of air-related maladies associated with exposure to particles smaller than 2.5μm (PM2.5)1. New Low cost air-sensors can be invaluable for large scale data collection, however, the reliability of these inexpensive air-quality sensors needs to be evaluated. Pallotto is working on a study with Professor Andrew Grieshop and Ph.D. candidate Stephanie Parsons  to determine the reliability and useability of three low-cost sensors (Atmotube, MicroPEM, Purple Air) to test methods for use in a pilot study on ambient personal PM2.5 exposure in rapidly urbanizing Nepal. 6 Purple Air sensors were installed in permanent locations throughout the Chitwan Valley of Nepal and data was collected in 2-3 day increments from four MicroPEMs and 17 Atmotubes sensors temporarily set in seven locations. First, two MicroPEMS were co-located together with 17 Atmotubes comparing the precision of the sensors. Next, a pair of each sensor, selected from 4 MicroPEMs and 5 Atmotubes, were collocated with several Purple Air sensors. Data from the first collocation shows strong agreement among Atmotube units, with an average percent deviance of 0.90 from the mean of ~112 μg/m3. Preliminary comparison with filter-based ‘reference’ measurements from the MicroPEMS suggests that the Atmotubes are ~11.5% lower on average. Background measurements from the Purple Air sensors show an annual PM2.5 average of ~50 μg/m3, over 4x higher than the annual PM2.5 standard in the US. Further analysis will explore PM2.5 diurnal trends, site comparisons, seasonal variations, and variations among sensor types, with continuing research where adolescents wear these monitors.