I am interested in an accurate indoor air quality monitor and I have mostly settled on the Air Gradient One vs the Purple Air Zen. I am primarily interested in C02 and PM 2.5. I live in an old home in a poor air quality city. There are a few things I think you will know to help make this choice.
The Air Gradient One lists “12 months data platform”. What happens after 12 months? The dashboard is one of the reasons I would choose air gradient over purple air.
PurpleAir has two PM sensors so you know if one goes bad. How long do these sensors typically last? Is there a way to track the sensor in the Air Gradient given it does not have PM sensor redundancy?
EPA correction factor. While I am planning on using the Zen indoors, it sounded like the EPA correction applied to Zen improved accuracy. Given that the AirGradient One uses the same manufacturer, is there any correction factor applied to the Air Gradient when viewing the data?
C02 calibration. I am confused about auto-calibration and the need for CO2 calibration between the two models. How often do the CO2 monitors need to be calibrated? We recently completed an indoor air quality study on our house and we had fairly high CO2 levels, so I am concerned auto calibration may be bad for our use case.
I appreciate any response you can provide! Keep up the great work!
Thanks for your message and for joining the forum! It’s great to have you here.
I’m more than happy to answer your questions, but please note that I work for AirGradient in a freelance capacity. I do my best to remain transparent and unbiased (and I’m free to speak on the things I don’t like about AirGradient monitors!), but I do want to make this clear. Just wanted to ensure you’re aware!
The platform will always remain free, and there is no intention to change that. The 12 months are for a ‘premium’ plan which includes some more advanced (and server-heavy) functions like setting multiple alarms, longer data retention, etc. So, after 12 months, you can continue to use the dashboard for free; you will only lose access to these features. If you do want to subscribe, it costs $2 per monitor per month. Of course, you always have the option of using something like Home Assistant if you want to keep unlimited data without paying.
It’s hard to exactly tell what their lifespan is, as they’re rated for 3-5 years, but I’ve seen some continue to perform well beyond this. If the sensor is indoors (where there probably isn’t too high a PM2.5 concentration), I would imagine the lifespan would be on the longer side. With the AirGradient device, it’s hard to tell when a new sensor might be needed, and the best way to tell is if the readings begin to seem unrealistic. In this regard, the Zen has an advantage, and it’s definitely easier to identify a failing (or drifting) sensor on it.
If you want to be on the safe side, you could replace the sensors every three or so years to minimise potential drift/issues which may be hard to identify otherwise.
Yes, AirGradient also supports the EPA correction as both brands use the same sensors. You can apply the EPA algorithm on the AirGradient dashboard.
It depends on the sensor, but I’ve found calibrations to not be needed very frequently. I tend to use manual calibration, and I probably only calibrate my monitors every 3-4 months.
Autocalibration sounds like it probably isn’t ideal in your case, so I would recommend toggling it off and manually calibrating every few months.
If you purchase the Zen, are you looking also to get a separate CO2 monitor?
Totally forgot the Zen doesn’t have a c02 monitor. Thanks for asking. I really appreciate this outline. I was having trouble finding these details through the websites. Hopefully anyone else searching your site for Purple Air Zen or Air Gradient One finds this helpful as well.
It’s one of the main reasons that I think the Zen is still very much an outdoor-focused monitor as opposed to the indoor/outdoor hybrid that it’s advertised as. It’s a fantastic monitor (my favourite outdoor monitor, actually!), but getting this and a dedicated CO2 monitor would be vastly more expensive than getting something like a ONE or Qingping Air Quality Monitor Gen 2.