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Airquality values confusion

Posted: Thu 01 Jul 2021 1:44 pm
by KarlS
It is not only dangerously hot here in British Columbia, but we also have dozens of wildfires burning within a 20km radius. So for the first time since I installed the Ecowitt WH41 PM2.5 Air Quality sensor the reported values are anything but “good”.

Code: Select all

      | 30/06/2021  | 01/07/2021
Time  | AQ1 AQ1avg  | AQ1 AQ1avg
------|-------------|-----------
05:00 | 21   14.7   | 37   63.0
05:10 | 22   14.8   | 44   61.1
05:20 | 17   14.8   | 49   61.2
05:30 | 18   14.8   | 48   60.8
05:40 | 16   14.8   | 47   60.3
05:50 | 19   14.9   | 46   59.9
CumulusMX reports these values as Extra Sensors Airquality Sensor1 and Sensor1avg. Since installation, the value for Sensor1 was always higher than Sensor1avg, so I assumed that Sensor1 was the peak value for the reporting time. This morning, the value for Sensor1avg is way higher than Sensor1, so Sensor1 can’t be the peak value. Maybe it is the last reported value by the sensor? But what are the chances that in the days before the last value reported was consistently higher than the average?

Re: Airquality values confusion

Posted: Thu 01 Jul 2021 1:59 pm
by Mapantz
I presume you have set your country's air quality index in Extra Sensor Settings?

Re: Airquality values confusion

Posted: Thu 01 Jul 2021 2:41 pm
by KarlS
Mapantz wrote: Thu 01 Jul 2021 1:59 pm I presume you have set your country's air quality index in Extra Sensor Settings?
Yes, it is set to Canada-AQHI.

On second or third thought, maybe the AQ average isn't calculated by CumulusMX but is a 1 hour (6 hour, 12 hour ?) average supplied by the Ecowitt gateway??

Re: Airquality values confusion

Posted: Thu 01 Jul 2021 6:55 pm
by freddie
I think the average is a 24-hour average - that seems to be the standard in the AQ world.

Re: Airquality values confusion

Posted: Thu 01 Jul 2021 9:51 pm
by mcrossley
As @freddie says, the average AQI standard is 24 hours, and iirc that is also what the Ecowitt supplies.

Re: Airquality values confusion

Posted: Thu 01 Jul 2021 10:39 pm
by KarlS
mcrossley wrote: Thu 01 Jul 2021 9:51 pm As @freddie says, the average AQI standard is 24 hours, and iirc that is also what the Ecowitt supplies.
Right, so the reported Sensor1avg is a 24 h average. Makes sense. That still leaves the question what the Sensor1 value represents. Is it an avg, peak or latest over my 10 minute time span?