Topic: Davis AirLink vs. PurpleAir Accuracy

[Slrpwr]

Has anyone compared the accuracy of the Davis AirLink to the PurpleAir PA-II? I have both installed at the same location and the PurpleAir reports consistently higher raw results at PM 2.5, 10 & 1.

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You can see the real-time results here: https://bollar.org/wx/saratoga/wxairquality.php

[ConligWX]

Mine is similar but the Airlink is set UK COMEAP AQI values

https://www.conligwx.org/pws/air-quality-charts.php

Airlink UK COMEAP AQI
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Airlink UA EPA AQI
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[Slrpwr]

For comparison, here's my Weather34 AQI page: https://bollar.org/wx/weather34/air-quality-charts.php

Maybe I should install the VOC sensor for completeness.

[mcrossley]

Mine is similar but the Airlink is set UK COMEAP AQI values

Looking at yours the AL seems to be lower at low values, but records higher values. Are your charts 24 hour averages?

[josecmorales]

For comparison, here's my Weather34 AQI page: https://bollar.org/wx/weather34/air-quality-charts.php

Maybe I should install the VOC sensor for completeness.

Airlink have more peaks unlike of PA

[Smithee]

Just picking up this topic - i have installed a Plantower sensor linked to a Raspberry Pi, next to the Davis and noting that that the Davis has much higher readings (screengrab attached) - if you then go and look at the purple air map vs the davis map, davis readings seem higher.

My Davis unit seems closely tied to the humidity (i know it affects the sensor) but the Pi Plantower less so.

I guess if you have two units you never truly know what the air quality is

Andy

[davidefa]

Interesting comparison, have you other graphs made in lower humidity conditions?

P.S.
Do you know which dust sensor is used by the airlink?

[Smithee]

There is a pic of the internals over at the cumulus forum - with a post around the Plantower A003?

https://cumulus.hosiene.co.uk/viewtopic.php?f=6&start=15&t=18417&sid=12d8927b7fada9887566f200d63f2a75

I've only had it running for a few days but the link to the humidity so far is very clear to see - i cant work out though why the Pi version (also a Plantower) does not follow suit though.

I know if you have multiple sensors then you never truly know what the correct reading is,  but i do have a suspicion that the Davis one (and thus the global map) is very dependent on humidity...

Andy

[weather34]

my airlink had been showing a constant 60-70 Epa for many weeks today I went out there and gave it a blast of condensed air (common air canister type used for  cleaning out PC equipment ) and below and hold 20 minutes later readings dropped considerably . I have noticed a particular trend to humidity in the past , Im located near the sea front so I kind of just put the observation to one side due to mostly saturated humidity but definitely a noticeable trend.

chart below reveals the rapid change down , I have nothing to compare it with outside apart from an indoor Nova Diy  SDS011 PM 2.5 kit I use .
so give it a good clean every few months ...

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[parkernathan]

I have a few test AirLinks (two indoors and one outdoors) since I work for AEM (now that Davis and Earth Networks are owned by AEM).

Here's my outdoor sensor:
https://www.weatherlink.com/embeddablePage/show/b8240747890046e7b4df5d65e371aa36/summary

I don't have a PurpleAir to compare it with. I also have the BreezoMeter app on my phone, so I could start comparing BreezoMeter with my AirLink.

I have the test AirLinks since I need to learn how to work across AEM companies (in addition to my Earth Networks work, I am doing some work across AEM family companies). We're also looking at some ways to use AirLink data at Earth Networks, hence another good reason for me to test one out.

[Snowda]

For those interested, SC-AQMD has done some evaluations of various devices: http://www.aqmd.gov/aq-spec/evaluations/summary-pm

As has METAS: https://www.metas.ch/metas/en/home.html

We've found the IQAir AVP & AV Outdoor to be the better options for us based on cost, accuracy, reliability and data availability.

Davis lacks a CO2 sensor which was a key drawback so we didn't look at it much further. As mentioned above, we saw other reports of humidity problems with them which raised concerns. IIRC they use a single reflective sensor rather than separate emitter+sensor for PM which might be an issue. I THINK the better devices use separate emitter+sensor (and often dual) and have airflow that cleans both of them to prevent/reduce stuff sticking to them.