Air Quality Sensor

California is suffering from fires all around us, and the SF Bay Area has terrible air quality.

My Tempest is arriving tomorrow, and I wonder if there is a air quality sensor I could buy to also monitor air quality.

Thanks for your help,


not specifically for the tempest. but there are some other available:
Personally I have the flow unit, which is portable with build in battery, but uses bluetooth. Ali has many more models. Purpleair seems a pretty solid bet (look at their map) and uses wifi.
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PurpleAir works fine. Simple to set up. Checkout for their map to see if there are already folks near enough to you to save you the $200 or so. is centered over California. Zoom in and check out the ugly story.

Wind must be prevailing SE => NW as the area around Lancaster is ‘much’ better than it was on Friday.


Thanks for the suggestions. If Weather Flow don’t make one in the future, I’ll consider this.

Their ‘Breathe’ product was canceled quite a lot of months ago if I recall correctly.

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new from davis standalone …


Should be interesting to watch how this evolves. The “easily merge with your Davis weather station” concerns me however,the page reads like you need to use their WeatherLink stuff to report to, which many folks try to avoid.

FWIW, you can grab the JSON reading from a PurpleAir just by querying a URL on the PA device on your LAN. You don’t even need to let it connect outbound to the PA network (although they ‘do’ push firmware updates occasionally, which can be helpful).


im sure in time getting the data will be available via the popular methods i.e meteobridge, weewx etc … fwiw nice to see it coming from a trusted brand…

i have a couple of air quality products one being the Nova SDS011 diy

and the other for a couple of years both can be used for third party website data viewing .


I’ve got the Nova SDS011 aswell, plus an Enviro+ with a PMS5003.

I also backed a Metriful on Kickstarter to have a play around with too


I am also running the Enviro+ with the PMS5003 (with an additional sg30 for VOC) - alongside a LaserEgg - they are interesting but also need calibration in fresh air first and then I’m not sure of their accuracy. Esp if you reboot the pi, the numbers shift. Anyhow, screengrab of my Grafana in case anyone is interested…

(edit - the air quality is poor - i had just fried some chips!)


If you would like some more detailed information about the PurpleAir I wrote an article about it along with quite a bit of information on integrating it into a smart home. You can find the article here:



Here is another article on PurpleAir that was just published yesterday

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Why Purple Air and Air Now may have different values:

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Thinking of Purple Air or Plume Labs Flow. Not sure if the Flow 2 is worth $70 more than the Flow 1, main difference seems to be that Flow 2 also measure PM1, in addition both Flow 1&2 measuring PM2.5, PM10, NO2, VOCs.

I had the flow 1 before the flow 2. In my opinion it wasn’t worth the upgrade. It’s battery operated, therefore mobile, but lasts only a day, so basically it is always in the charger. At some point the battery will give up. I would have preferred if it used wifi for 24/7 operation. Currently it only transmits data when my phone is in range and bluetooth is on (which most of the time it isn’t). Other than that, it is working fine

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Liking the Flow, or Flow 2, since it also Measures NO2.

Excellent new online map available at lets you drill down visually, and includes permanent, temporary, and low-cost (Purple Air etc.) sensors.


I posted earlier about the California Wildfires and Air Quality. Got some good suggestions on Air Quality sensors. Purchased the Plume Labs Flow 2.

But I’m confused. It does not appear values such at PM 2.5 are equivalent on Flow 2 vs. what Purple Air publishes online. And the AQI numbers seem to be calculated differently.

Help, I just want to check my local Air Quality, and compare to what’s online.

Thanks for your thoughts.

long discussion in Air Quality Sensor and a link to a page that explains the differences…

Here near Tacoma we just went from AQI of 20 to AQI of 300 as a wall of smoke from the central Washington fires hit us. You could see it coming, the Cascades and MtRainier disappeared and we couldn’t even see the landing lights of the planes going in to SeaTac Airport. Amazing.

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there are many (too many) different AQIs in the world. Plume uses their own.

What you can see in the last graph on that page is that the none of the AQI is linear depend on the concentration of pm2.5.
For example, there is a sharp bend in the orange (USA(24)) curve at 150 and again at 200. The Plume index also isn’t linear. If you scroll down on that page there is a little table that give you the values of when there is a bend in the Plume curve. You could use that, to get from the plume values to the concentration of pm2.5.

Or you could use the download data in your app, and you get the data that does include the concentrations.

I wish they would also display the concentration in ug/m3 (please do bug them about that… more than once!).