Outdoor Air Quality Monitors

While my website initially focused mostly on outdoor air quality, that changed over time as the pandemic hit. Despite my interest in outdoor air pollution ([that is the reason I started my blog] (BreatheSafeAir • About Me)!), I recognised that there was a much more pressing matter at hand: indoor air pollution.

While the pandemic is far from over, I now have more time to focus on outdoor air quality monitors again. Recently, I was finally able to review my first dedicated outdoor air quality monitor - the AirGradient Open Air. I was impressed with the monitor and loved how much insight it gave me into the concentrations and make-up of outdoor air. Since that review, I’ve wondered how other outdoor air quality monitors perform.

I have the Purple Air Zen on the way for testing. Still, in the meantime, I wanted to start compiling a list of outdoor air quality monitors that are in a relatively similar price range (within reach for most consumers) and have a similar feature set. While I’m sure I’ve missed many, as this list is just off the top of my head, here are the monitors I’ve looked at so far.

Air Quality Monitor Pollutants Measured Sensors Cost
AirGradient Open Air PM (PM1.0, PM2.5, PM10) & CO2 (on newer models) PMS5003T, S8 $125 (DIY), $190 (Assembled)
PurpleAir Classic PM (PM1.0, PM2.5, PM10) 2x PMS5003 $229
PurpleAir Flex PM (PM1.0, PM2.5, PM10), Pressure, Temperature, Humidity & Gas 2x PMS6003, BME688 $289
PurpleAir Zen PM (PM1.0, PM2.5, PM10), Pressure, Temperature, Humidity & Gas 2x PMS6003, BME688 $299
AirVisual Outdoor PM (PM1.0, PM2.5, PM10), temperature, humidity, air pressure, & CO2 (optional) (unsure. Likely IQAir co-developed sensors as with the AirVisual Pro) €319.00

As I mentioned, this list of outdoor air quality monitors is far from complete, and I’m sure I’ve missed many. However, both for my own sake and anybody considering an outdoor air quality monitor, I will update this in the future as more monitors come across my radar!

I forgot to add the Model X from CO2 Click to the list. The Model X is another great, affordable option.

For Canadian $209, you can get a monitor with a Sensirion SPS30 and Bosch BME280. I haven’t yet tried this monitor either, but it’s small form factor and inconspicuous look could make it ideal for some uses.

I am currently testing the Purple Air Zen (Purple Air’s newest outdoor air quality monitor). So far, I am still in the early phases of testing, so I won’t go into details yet, but I do have a few first thoughts.

For anyone wondering, the Zen and the Flex are quite similar, but the Zen looks to be positioned as the successor to the Flex as it’s both slightly more expensive and has a few extra features. However, both monitors have the same sensors (two Plantower PMS6003 sensors and a Bosch BME688).

Interestingly, however, the Zen seems to be an incredibly incremental update, and I have to wonder why the choice to release it and sell it alongside the Flex was made. As per this post on PurpleAir’s forum, the only two major differences are the LED ring and double-tap functionality (to change LED brightness) on the Zen.

Based on this, I have to assume the Flex is meant more for applications where people don’t want the monitor to be noticed as it’s very inconspicuous. On the other hand, the Zen is made to stand out.

I will be sharing more thoughts soon!