ABSTRACT Low-cost light scattering monitors (LCMs) are promising tools as alternatives to research grade, higher-cost instruments to provide real-time, high resolution monitoring of fine airborne particulate matter (PM) thereby supplementing traditional filter-based gravimetric methods. The LCMs must however be calibrated to get correction factors (kcf) to be comparable to research grade instruments that serve as benchmark instrument for reporting PM mass concentrations. This study aims at evaluating kcf of five commercially available LCMs, namely YesAir operated in diffusion mode (YAd), YesAir operated by internal pump (YAp), Aeroqual S500 (Aq), NuoFang SDL607 (NF) and Dylos DC1700 (Dy), against a TSI DustTrak Environmental Aerosol Monitor 8540 (DT) benchmark instrument. The evaluation is based on three individual particle sources: burning of candle, cigarette and incense. The obtained kcf was found to be dependant on both source and the mass concentration of PM2.5. Depending on the LCM and source, concentration dependency of kcf values at five concentration ranges (0-5 µg/m3, 5-20 µg/m3, 20-50 µg/m3, 50-100 µg/m3 and 100-1000 µg/m3) shows that kcf follows one of the five patterns over the concentration range: (1) decrease, (2) constant, (3) constant then decrease, (4) decrease then constant and (5) decrease then increase. On the other hand, correlation expressed as coefficient of correlation (R2) increases when PM concentration increases. The results demonstrated the challenges in calibrating LCMs for their application in real-world PM monitoring campaigns.
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