After only 10 months one of the three sensors has failed altogether and another one gives ridiculous results. The third sensor tracks my PurpleAir well, but unfortunately the aqicn website only shows the ridiculous figure. . .
Problem is, I can’t contact aqicn. I’ve tried the support e-mail address I was given, used the message facility on my dashboard and a contact address from their website to no avail. Does anyone have a working contact address?
Yes, one sensor failed after two months and six contact attempts were unresponded. Would never buy from them again, lousy service mindedness … just want the money?. Also, very very few reviews are to be found, why is that I wonder?
Still no contact with them. . . I chose the “annual rental” option, with an added “deposit”, so I suppose I should count myself fortunate that they did not take the payment due on 2 September.
Meanwhile, my PurpleAir sensor is working well 
Well done in avoiding further payment … a propitious choice of plan, as it turned out.
What now intrigues more is the virtually complete absence of Gaia station reviews … it’s unusual. Looking further into replacement sensors (easy to find and not expensive), it would not be unreasonable to think its quite a profitable enterprise, especially as they appear to take no responsibility for replacing kit failures.