“…The informative value of the PM 2.5 samples could be enhanced if filters undergo additional analysis, such as chemical characterization, or reflectance to measure black carbon (Yan et al, 2011). Direct-reading instruments with data logging capabilities may have decreased sample collection time, and increased the informative value by allowing for assessment of peak exposures (Wells et al, 2013;National Research Council, 2012). However, study designers should consider the availability and cost of the device, the complex data management, and the instrument cleaning, maintenance, and calibration requirements before choosing a direct reading instrument.…”