Here is the situation: for a few nights now I have observed unusually high AQ readings while the air quality was actually fine. I'm now trying to figure out what the reasons for these mis-readings are. First off: it's not the battery (fully charged) and not the humidity (around 70%, no snow or flurries).
The Ecowitt web site states:
Possible, but this can't be the (only) reason, since the temperature/dew point difference was below 2°C most of yesterday morning and the AQ readings were not affected (the light green shaded areas are below 2°C difference).When the Dew Point is close to the outdoor temperature (T - D < = 2C), the PM2.5 reading will be very high (which is not the real condition). If mind, please don't purchase.
Another reason – or a combination with the above – could be the temperature. False readings only occurred at temperatures below -6.5°C. But shouldn't an AQ sensor specifically built for outdoors work at these temperatures. What will happen when it hits -30°C in a few weeks' time?
And why is it happening only at night? I've been brainstoring with my wife and we now believe it's a Sasquatch (the North American version of a Yeti) lying down for the night under the sensor. Maybe some of you can find a better explanation ...
On a related issue, it would be nice to be able to set a spike limit for AQ sensors to catch errors like these: