During the winter and spring of 2022, South Coast Air Quality Management District (SCAQMD) evaluated the field performance of the AirBeam3 against two Federal Equivalent Method (FEM) instruments. The results showed strong to very strong correlations for the AirBeam3’s PM1 and PM2.5 measurements, with R-squared values ranging from 0.81 to 0.99, and weak correlations for the AirBeam3s PM10 measurements, with R-squared values ranging from 0.19 to 0.37. An R-squared value of 1 would mean there was a perfect correlation between the measurements from the FEM instrument and the AirBeam3. The above graph is taken from SCAQMD’s AirBeam3 evaluation. The red line represents the measurements taken by the reference instrument while the blue, green, and yellow lines represent the measurements taken by three colocated AirBeam3s. The complete results from the evaluation can be downloaded via SCAQMD’s AQ-SPEC website. We’d like to thank the folks at SCAQMD for running the AQ-SPEC program and evaluating the AirBeam3. The AQ-SPEC program is an invaluable and impartial source of information on low-cost air quality instruments.