This list contains definitions for fields that can be obtained from a sensor’s local JSON data . Many of these fields are also the same as the information recorded to the SD card . This documentation is current for the 7.04 version of sensor firmware. For any PurpleAir sensor with two laser counters…

[image] PurpleAir: pm2.5_aqi_b From what I have read, embedding a “.” in a json key name is really bad form. And it is really giving me grief in trying to process this. It seems out of context in light of the other key names being used and there must be some other, better, notation. Sheesh!

It is indeed really bad form :confused: But, it can usually be worked around - e.g, something like // JS const airQuality = data[“pm2.5_aqi_b”]; // Python air_quality = data[“pm2.5_aqi_b”]

Thanks. In the intervening 3 months or so, I suddenly realized it was just text and I could edit it and deal with it that way. So I did and it has been fine since then. Best!

It was an early mistake that has been kept for backward compatibility. We completely understand it can be frustrating to work around.

Is it just me? I am not seeing any channel_flags field in my Flex’s json results (both with and w/out ?live=true). I don’t see it in the json docs here . I thought maybe it was in one of the status fields. But it does not seem that is the case either. Did this go away at some point? Seems a useful …

channel_flags are not included in the local sensor JSON because flagging is handled on PurpleAir servers, not on device. I’m not aware of a time when this field was available locally on the sensor. To be clear, channel_flags indicate internal, server-recognized “downgrades” to a laser counter data …

Thanks so much Andrew! Any idea of the pseudo-algorithm used server-side to recognize this? I could maybe implement it on my own server. Best

Sensor JSON Documentation

Data

Andrew (Andrew) August 10, 2026, 5:48pm 10

Yep, it’s documented here! How the Confidence Score is Calculated

Topic		Replies	Views
Local JSON endpoint documentation Data	7	1574	December 20, 2023
Understanding PurpleAir Serial Output Data	0	2455	January 11, 2023
Custom Data Processor Schema Data	1	623	October 11, 2022
API Fields Descriptions API	19	5871	February 18, 2026
Version and hardware versions in PA json Sensors	4	224	June 6, 2024

Sensor JSON Documentation

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