Purple Air. The Pioneer in Low-Cost PM Monitors Purple Air played a significant role in making low-cost air quality monitors accepted by the public and government institutions. There are now a significant number of studies available comparing the Purple Air monitors against reference instruments and proposing correction formulas to make them more accurate. It’s probably the most studied air quality monitor out there. We at AirGradient are thankful for the impact of the Purple Airs and the way it...