AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Evaluations of Three Commercially Available Indoor PM2.5 Monitors
MISTI ZAMORA, Kirsten Koehler, Johns Hopkins Bloomberg School of Public Health
Abstract Number: 599 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract The availability of low-cost monitors marketed for use in personal homes has increased rapidly over the past few years due to the advancement of sensing technologies and the rise of citizen science. The user-friendly packages can make them appealing for use in indoor exposure projects, but a rigorous scientific evaluation has not been conducted for many monitors on the open market, which leads to uncertainty about the validity of the data. We evaluated six monitors (two Air Visual Pros, two Speck sensors, and two Airthinx) over a one-year period in a residential setting. All of the selected monitors measure PM2.5 mass concentration, temperature, relative humidity, store data internally, and have a way to indicate poor air quality to the consumer. Two units of each type of monitor were evaluated to determine the precision between units, and a personal DataRAM (pDR-1200) with a filter was placed in the home for about 20% of the sampling period (e.g., about a week each month) to evaluate the accuracy over time. The average PM2.5 mass concentrations from the periods of colocation with the pDR were 8.64 µg/m3 for the pDR-Filter, 9.66 µg/m3 for the pDR-Nephelometer, 8.00 and 8.02 µg/m3 for the Air Visual Pro units, 13.02 and 21.28 µg/m3 for the Speck units, and 12.05 and 10.36 µg/m3 for the Airthinx units. The Air Visual Pro exhibited the best accuracy at 88%, which was comparable to the nephelometric component of the pDR compared to the filter weight (also 88%). The accuracy of the Speck and Airthinx were -207 and 43%, respectively. The precisions of the Air Visual Pro, Speck, and Airthinx were 0.11, 0.38, and 0.18, respectively. For comparison, ambient regulatory instruments must be below 0.10. The Pearson correlation coefficients (R2) between units of the same type were 0.99, 0.52, and 0.91 for the Air Visual Pro, Speck, and Airthinx, respectively. The R2 between the units and the pDR were 0.98, 0.45, and 0.91 for the Air Visual Pro, Speck, and Airthinx, respectively. Overall, the reliability of these types of monitors is strongly dependent on the model, so an evaluation of each type of monitor is essential before the data can be used to assess residential exposures.