Our community has several monitors all in the same direction relative to an emitting source. The VOC readings are extremely high - higher than the monitors are programmed to read. We were told that the calibration is not functioning correctly. The three monitors, however, all have the same pattern of readings. Are the monitors actually measuring VOCs or are they measuring other things like humidity…? If they are measuring VOCs is there an algorithm or something that we can apply to the readings to correct them?
I don’t know the answer to your question, but it does appear that the latest generation of PurpleAir monitors appears to change its responsiveness to environmental conditions. We recently had some very stinky days in Pittsburgh (overnight May 22, 23, and 24) and you can see that the blue line (BL-ZEN-005) shows spikes ONLY during those stinky days. This device is new in 2023. The other line (black line for BL-FLEX-001) shows the up and down variation and was recorded by a 2022 generation FLEX device. It seems that something has changed and I’d love for PurpleAir to weigh in and offer an explanation. I’ll keep looking into it as well as I dig into it all.
(edited to correct the image – I had previously uploaded a different unrelated image)
Best,
Mark