Author Topic: Wondering now about these...  (Read 1110 times)

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Offline azchrisf

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Wondering now about these...
« on: April 12, 2018, 07:26:39 PM »
Today is a huge windy day here in Phoenix - the NWS has put out a Wind Advisory, and the Dust concentration should be much higher than is being registered on my Purpleair.

For example, the EPA monitor about 2 miles from me (http://aqicn.org/city/usa/maricopa/glendale/) is registering 107 AQI, yet my Purpleair is only saying 7 for PM 2.5 and 2 for PM10. I know it has to be higher than that considering when the wind picks up to 25 MPH the dust comes with it from out of town.

I'm starting to wonder if these devices can be trusted - at all.

Offline azchrisf

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Re: Wondering now about these...
« Reply #1 on: April 13, 2018, 03:46:49 AM »
True. I've sent them an email asking for an explanation how every Purpleair monitor is showing single-digit AQI when all the Federal/State AQI monitors are showing the dust is certainly out there...

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Online weather34

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Re: Wondering now about these...
« Reply #2 on: April 13, 2018, 05:16:16 AM »
yes never make bold statements until proven

your quote...

I disagree on the accuracy. Purple air sensors were put up against 25 thousand dollar machines and they tracked the pollution very well They were OKish with PM10 but did excellent on PM 2.5 Read the links to the independent testing facility on Purpleairs sit

1st or second generation products often fail or show anomalies  when it really matters  .

lets hope it improves its a rather expensive add on , i toyed with one if these but at the current price my disposable income wont warrant one just yet and this sort of increases my doubts about them. hoping for better news .

brian


Offline SLOweather

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Re: Wondering now about these...
« Reply #3 on: April 13, 2018, 01:03:29 PM »
Y'all do realize that the AQI is more than just PM 2.5 and PM 10? It can include O3, CO, SO2, and NO2.

Offline graculus

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Re: Wondering now about these...
« Reply #4 on: April 13, 2018, 02:50:56 PM »
The fans in the sensors are very weak. I wonder if a strong wind blowing across the bottom of the unit generates negative pressure and the sensors don't get a good air sample.

 

anything