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Description
Particulate matter with an aerodynamic diameter of <2.5 micrometers (PM2.5) is worldwide air pollutant and a contributor to mortality and morbidity globally. Low cost, direct-reading monitors are currently used to sample PM2.5 in ambient, occupational, and residential or community-based settings to quantify air quality and public health outcomes. However, many of these devices have been found to underestimate and overestimate particulate matter concentrations, even with calibration methods and calculations. Environmental chambers can be used to create controlled conditions to assess sensor performance under different conditions and evaluate the capabilities of low-cost monitors in obtaining reliable data. In this study, the evaluation of a full-size chamber and its ability to produce stable mass concentrations of PM2.5 over time was researched as a potential alternative for calibrating low cost sensors in the field. PM2.5 and PM1 mass concentrations for candle and incense emissions in the chamber were evaluated using DustTrak DRX monitors. Particle number counts (PNC) for Ultrafine particles (PM.1) were measured with collocated Condensation Particle Counters (CPC). Sampling runs with monitors took place over periods of 30 to 90 minutes with different sizes of candles and incense wicks. It was discovered that the chamber can produce stable concentrations when different emission sources were introduced within the chamber. Overall, PM2.5 mass concentrations were <5 + 2 μg/m3 in the clean chamber without emission sources based on 30-minute sampling runs. PM2.5 mass concentrations with different candle sizes were generally <100 +11 μg/m3 while PM2.5 mass concentrations with incense were generally >1,000 +100 μg/m3 based on 30-90- minute sampling runs. Pearson correlation coefficients were >.90 between DustTrak DRX monitors, revealing that the monitors were measuring highly correlated PM2.5 mass concentrations. A Pearson correlation coefficient was >.94 between PM1 and PM2.5 mass concentrations within several sampling runs, indicating strong correlation between the two measurements. The highest PNC was 318,912 particles/cm3 by the 1/4 incense wick, while the lowest PNC was 10,507 particles/cm3 in the clean chamber. This study concluded that a full size chamber can be built feasibly and at a low cost and produce stable concentrations of particulate matter over set sampling periods.
