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Weather Station Hardware => Air Quality Sensors => Topic started by: mmorris on July 17, 2017, 11:05:30 PM

Title: personal air pollution sensor
Post by: mmorris on July 17, 2017, 11:05:30 PM
Got this post FaceBook $229.00 to $259.00 to by a sensor.  There is maps to click on at the bottom of the web site. Here is the post on WU https://www.wunderground.com/cat6/purple-airs-250-air-pollution-monitor-gives-government-equipment-run-money?__prclt=mEVwbM1N


Thinking about a personal air pollution sensor? Based on cost and on laboratory and field evaluations by air pollution experts, we recommend the PA-II by PurpleAir (purpleair.com (http://purpleair.com)) as the best outdoor air pollution monitor for personal use.
Title: Re: personal air pollution sensor
Post by: K8POS on September 25, 2017, 01:07:29 PM
I got the same email as most everyone else did.  I have been giving it serious consideration.
A lot will depend on the ability to integrate some of the data into my own personal web site, not just what Purple air has.
Either Purple air, or WU needs to supply everyone with a widget they can add to their station that will display the current AQI, but then link to the Purple Air for more info.

Bob
Title: Re: personal air pollution sensor
Post by: eliteweathernz on September 25, 2017, 05:51:35 PM
Hi guys,

Weather Display Software is intergrated with the Purple Air Sensor and data can be displayed.

Depending on the software your using you may have limitations.

I’m sure in time Purple Air will work towards some form of app or other intergration for weather buffs to add data to there website.

Data can be downloaded in JSON format from the website if you know your sensor I’d.
Title: Re: personal air pollution sensor
Post by: eyecue on September 25, 2017, 08:38:21 PM
The actual sensors are not expensive, but Purple Air uses 2 identical ones to correlate data against itself and provide redundancy.
Title: Re: personal air pollution sensor
Post by: K8POS on September 26, 2017, 11:21:15 AM
I sent Purple Air an Email,
I asked if they had a target date to include Ozone in their sensor.
After really thinking about it, I would do this once they include Ozone.

Title: Re: personal air pollution sensor
Post by: azchrisf on September 27, 2017, 12:44:04 PM
I'd love to get one too, but it needs to be integrated with WU's station page like Davis Soil/Leaf sensors are, otherwise it's just one more gadget, one more thing I have to go to somewhere seperately to monitor, etc.

Having all the data at your fingertips is key. An API to pull data is important too, such as if I want to populate a SQL DB or a Meteotemplate, etc.
Title: Re: personal air pollution sensor
Post by: Toxic on September 27, 2017, 03:11:12 PM
There are two ways to access the JSON data:

All sensors: https://www.purpleair.com/json

One entry: https://www.purpleair.com/json?show=<ID> where ID is the “ID” of the sensor you want (in the case of dual laser where ParentID is “null”).

I am thinking of getting one of these to for my area as there are none even from government or local councils.

More info on the fields of data can be gained from contacting them, they are however a bit slow in responding.

afaik there is also a web/widget code they are working on for websites, and WU will be mapping the sensor data too, though not sure if this is tied into your own PWS site on WU.

Title: Re: personal air pollution sensor
Post by: azchrisf on October 24, 2017, 01:52:53 AM
I pulled my sensor data JSON but it has nothing like their webpage that shows history, etc.
I can't even get the current AQI from the JSON file, not there.

Starting to look like a dud. Map sucks (weird sensors show up on the left), no web widget, poor API...
Hardware is interesting but the key is having software to back it up. You can't even update your sensor info via their website.

Pretty poor IMHO. Wasn't ready for launch.
Title: Re: personal air pollution sensor
Post by: Toxic on October 24, 2017, 06:35:32 AM
Starting to look like a dud. Map sucks (weird sensors show up on the left), no web widget, poor API...
Hardware is interesting but the key is having software to back it up. You can't even update your sensor info via their website.

Pretty poor IMHO. Wasn't ready for launch.

It does seem they have jumped the gun so to speak. I'm holding off until I hear some more and if WU will add AQI to the users WU Weather Station site.

Would also be nice if this unit could save to a mysql database locally.
Title: Re: personal air pollution sensor
Post by: azchrisf on October 24, 2017, 09:42:48 AM
Yeah I think it's a good idea to hold off until they do some more work on the software.
Title: Re: personal air pollution sensor
Post by: Billbo on November 18, 2017, 10:46:52 PM
I live next to a gas pipeline compressor station, under construction. Anyone want to buy my now worthless property? Short of that, does anyone have a sense of whether the PurpleAir monitor will measure pollutants typical of these facilities...O3, CO, NO2, SO2, PM2.5, PM10, Pb?  Or is this just a simple monitor that says, "Hey, there is stuff in your air, but we don't know what it is"?

My email to PurpleAir went unanswered. Not a good start.
Title: Re: personal air pollution sensor
Post by: azchrisf on November 19, 2017, 12:58:35 AM
It measures PM 2.5 and PM10, but no gases.
Check the Purpleair Map to see what it will show you.
Title: Re: personal air pollution sensor
Post by: halifax on November 19, 2017, 07:34:21 AM
I have one and it was a seamless install and requires no attention. Just getting ready to update WD and get my data there. My interest is focused on PM2.5 so it works well for me.  It's pretty fascinating to watch the air quality change with the weather/wind patterns here in New England.
Title: Re: personal air pollution sensor
Post by: Billbo on November 19, 2017, 08:52:56 AM
... It's pretty fascinating to watch the air quality change with the weather/wind patterns here in New England.

Question from victim of a liberal arts education: Do weather/wind patterns in and of themselves affect PM2.5? Or is the change because of what pollutants float in from surrounding areas?
Title: Re: personal air pollution sensor
Post by: Billbo on November 19, 2017, 09:45:14 AM
It measures PM 2.5 and PM10, but no gases.
Check the Purpleair Map to see what it will show you.

I just looked at the map. All I see is measurements for PM2.5--not PM10. Is that because PM2.5 is the greater health concern, or am I missing a setting on the map?
Title: Re: personal air pollution sensor
Post by: Toxic on November 19, 2017, 10:06:46 AM
Quote from: Billbo
I just looked at the map. All I see is measurements for PM2.5--not PM10. Is that because PM2.5 is the greater health concern, or am I missing a setting on the map?
Dont think your looking on the right area of the map.  click on a site and wait for the details to populate.

 [ You are not allowed to view attachments ]  [ You are not allowed to view attachments ]
Title: Re: personal air pollution sensor
Post by: halifax on November 19, 2017, 10:50:05 AM
... It's pretty fascinating to watch the air quality change with the weather/wind patterns here in New England.

Question from victim of a liberal arts education: Do weather/wind patterns in and of themselves affect PM2.5? Or is the change because of what pollutants float in from surrounding areas?

Particulate-cloud parcels can move with wind patterns.

PM2.5 is particulates <2.5 microns and they tend to stay aloft vs. settle out and travel deeply into the furthest reaches of the lungs. The normal flushing mechanism of the lungs is not very effective at removing them. PM2.5 is generally from human sources with natural contribution almost insignificant. Since I live in a rural area, PM2.5 is a good signature indicator of situations upwind.

Learned a lot about this in grad courses including boundary layer climatology, forest meteorology, and environmental law and policy.
Title: Re: personal air pollution sensor
Post by: Billbo on November 19, 2017, 03:23:51 PM
Quote from: Billbo
I just looked at the map. All I see is measurements for PM2.5--not PM10. Is that because PM2.5 is the greater health concern, or am I missing a setting on the map?
I see in your image where it says, "Short-Term PM2.5 is Low." I see nothing about PM10. What am I missing here?
Title: Re: personal air pollution sensor
Post by: azchrisf on November 19, 2017, 03:43:33 PM
It focuses on PM 2.5.
Look in the graphs under Particles tab - that is where the PM10 data is.

You can click each different size in the chart key to eliminate all but the one/ones you want.
It does not show text data for PM10, but you can pull it out of the JSON file if you are a web wizard.
Title: Re: personal air pollution sensor
Post by: Billbo on November 19, 2017, 03:45:49 PM
It focuses on PM 2.5.
Look in the graphs - that is where the PM10 data is.
Oh, okay. So then, PM10 = 10PM here, correct? I managed to skip chemistry class. :oops:
Title: Re: personal air pollution sensor
Post by: Bunty on November 19, 2017, 11:21:52 PM
If I got one it would be interesting how it's readings would compare with the one somebody else in town has installed.  Probably much the same, though.
Title: Re: personal air pollution sensor
Post by: Eno on December 01, 2017, 11:33:34 AM
If I got one it would be interesting how it's readings would compare with the one somebody else in town has installed.  Probably much the same, though.

Sometimes yes sometimes no.  This morning here in Boise Idaho, no.

Two sensors less than three miles apart, mine reading 117 the other one 77.  I think that one gets some down-drainage flushing at night whereas I'm about 100' higher and farther away from the local foothills. In the daytime the readings tend to converge. boise.purpleair.com
Title: Re: personal air pollution sensor
Post by: halifax on December 01, 2017, 12:06:12 PM
I've noticed micro-scale events ... such as, cook breakfast with an exhaust fan on and the aerosol from cooking bacon sends the numbers up for a few minutes and then things settle back down ... if it's calm out.
Title: Re: personal air pollution sensor
Post by: azchrisf on December 01, 2017, 12:08:07 PM
I've noticed micro-scale events ... such as, cook breakfast with an exhaust fan on and the aerosol from cooking bacon sends the numbers up for a few minutes and then things settle back down ... if it's calm out.

This is why it should be placed somewhere it will receive readings representative of the area and away from things like vents that can unnecessarily effect it, but sometimes it's a compromise.
Title: Re: personal air pollution sensor
Post by: halifax on December 01, 2017, 12:14:52 PM
I have mine mounted on the side of the house furthest from the kitchen ... and I live in a ravine ... so in very calm conditions, it's easy for fumigation-type conditions to occur. It's not a common thing, but I did notice it a couple of times and correlated it to the kitchen.

I do like the internal cross-checking and the darn thing just runs and runs without any need to futz around with it.
Title: Re: personal air pollution sensor
Post by: azchrisf on December 01, 2017, 12:24:32 PM
I have mine mounted on the side of the house furthest from the kitchen ... and I live in a ravine ... so in very calm conditions, it's easy for fumigation-type conditions to occur. It's not a common thing, but I did notice it a couple of times and correlated it to the kitchen.

I do like the internal cross-checking and the darn thing just runs and runs without any need to futz around with it.

Interesting. I notice with mine it spikes in the morning and evenings, probably people coming and going to work. It also does it on the weekends from 10pm-2am. I'll have to figure out what the weekend thing is about...
Title: Re: personal air pollution sensor
Post by: mmorris on December 07, 2017, 05:59:19 AM
Well I look at the map and there wasn't any sensor around Barberton Oh. so I bit the bullet and ordered one. Seem to be a delay in getting one email below. Also sit here wondering where all the sensor are that Determine why I need to have my Vehicles E checked every two years and people that live 2 miles away don't.....

Dear valued PurpleAir customer.

You are getting this message because you ordered a PurpleAir air quality sensor.
When parts arrived recently, there were some key items missing.  We were still able to make quite a few sensors and get those out.  We are now waiting for those missing items to arrive in order to make the rest of the sensors.
PurpleAir really appreciates your patience as we work hard to get your sensors made, tested and sent out.
You will receive an email with the tracking number as soon as sensors are shipped, so be on the lookout for that.
If you have any further questions please let us know. 

Thank you for your continued support and patience.

Kind regards

PurpleAir Team
Title: Re: personal air pollution sensor
Post by: Toxic on December 07, 2017, 06:27:45 AM
Well I look at the map and there wasn't any sensor around Barberton Oh. so I bit the bullet and ordered one. Seem to be a delay in getting one email below. Also sit here wondering where all the sensor are that Determine why I need to have my Vehicles E checked every two years and people that live 2 miles away don't.....

Dear valued PurpleAir customer.

You are getting this message because you ordered a PurpleAir air quality sensor.
When parts arrived recently, there were some key items missing.  We were still able to make quite a few sensors and get those out.  We are now waiting for those missing items to arrive in order to make the rest of the sensors.
PurpleAir really appreciates your patience as we work hard to get your sensors made, tested and sent out.
You will receive an email with the tracking number as soon as sensors are shipped, so be on the lookout for that.
If you have any further questions please let us know. 

Thank you for your continued support and patience.

Kind regards

PurpleAir Team

I'm just wondering how my due diligence WU actually done on this company before plugging their product?

Looks like they have serious supply issues which means they are not even prepared for orders.

Excuses after excuses usually means one thing......
Title: Re: personal air pollution sensor
Post by: R_o_B on December 08, 2017, 08:41:34 AM
Looks like they have serious supply issues which means they are not even prepared for orders.

Excuses after excuses usually means one thing......
Hello Simon.

You will soon find out that their customer service (assistance to any questions) is also very very poor!

I purchased my PurpleAir sensor in March 2017 - that was before the joint venture of Adrionics/Weather Underground. In my first eMail exchanges (before I purchase the sensor), all my questions were promptly answered. After the purchase, as I was trying to find out how to get the most data out of my sensor (such as how to access the 'ThingSpeak.com' cloud database where all the PurpleAir sensors data are stored), well ... I have not received a decent and informative reply other than a poor and outdated link on Google.

I dread (apprehensive/anxious/fear/terrified/worry  ](*,)) of the day when my sensor becomes defective...
Title: Re: personal air pollution sensor
Post by: azchrisf on December 08, 2017, 09:34:18 AM
FYI for everyone - Purpleair sent me a Javascript file to get & calculate the AQI value from the JSON file they have. If anyone wants it let me know.

Problem is, I don't know how to program with Javascript. I do VB.NET, and a tiny bit of PHP.
Does anyone have any PHP scripts that can scrape the value out of the JSON file? I'm trying to directly put the AQI value on my website copperwoodwx.com instead of a link to their map.
Title: Re: personal air pollution sensor
Post by: waiukuweather on December 08, 2017, 01:10:10 PM
weather display supports this sensor and calculates the AQI and makes that available as a custom tag and lots of other associated custom tags as well too
Title: Re: personal air pollution sensor
Post by: donj51 on December 09, 2017, 10:04:54 AM
FYI for everyone - Purpleair sent me a Javascript file to get & calculate the AQI value from the JSON file they have. If anyone wants it let me know.

I sure would like the file.  Thanks in advance.
Title: Re: personal air pollution sensor
Post by: Toxic on December 09, 2017, 10:11:40 AM
FYI for everyone - Purpleair sent me a Javascript file to get & calculate the AQI value from the JSON file they have. If anyone wants it let me know.

I sure would like the file.  Thanks in advance.
https://www.purpleair.com/json

Sent from my ONEPLUS A3003 using Tapatalk

Title: Re: personal air pollution sensor
Post by: azchrisf on December 11, 2017, 10:05:01 AM
Im sure it will be more time saving just to attach it for those who want it.

Quote
In this JSON is a value called stats that has a value "v" inside it.  This is the realtime value in micrograms /m3

We do have some javascript to convert from the micrograms value to an AQI

If this is helpful it is included below.

Kind Regards
Amanda


In JavaScript, this line is how you get it:
 
var AQI = aqiFromPM(pmvalue);
 
 
And here are the functions:
 
function aqiFromPM(pm) {
      //return 0;
      if (isNaN(pm)) return "-";
      if (pm == undefined) return "-";
      if (pm < 0) return pm;
      if (pm > 1000) return "-";
        /*     
              Good                              0 - 50         0.0 - 15.0         0.0 – 12.0
        Moderate                        51 - 100           >15.0 - 40        12.1 – 35.4
        Unhealthy for Sensitive Groups   101 – 150     >40 – 65          35.5 – 55.4
        Unhealthy                                 151 – 200         > 65 – 150       55.5 – 150.4
        Very Unhealthy                    201 – 300 > 150 – 250     150.5 – 250.4
        Hazardous                                 301 – 400         > 250 – 350     250.5 – 350.4
        Hazardous                                 401 – 500         > 350 – 500     350.5 – 500
        */
        if (pm > 350.5) {
          return calcAQI(pm, 500, 401, 500, 350.5);
        } else if (pm > 250.5) {
          return calcAQI(pm, 400, 301, 350.4, 250.5);
        } else if (pm > 150.5) {
          return calcAQI(pm, 300, 201, 250.4, 150.5);
        } else if (pm > 55.5) {
          return calcAQI(pm, 200, 151, 150.4, 55.5);
        } else if (pm > 35.5) {
          return calcAQI(pm, 150, 101, 55.4, 35.5);
        } else if (pm > 12.1) {
          return calcAQI(pm, 100, 51, 35.4, 12.1);
        } else if (pm >= 0) {
          return calcAQI(pm, 50, 0, 12, 0);
        } else {
          return undefined;
        }
     
      }
      function bplFromPM(pm) {
      //return 0;
      if (isNaN(pm)) return 0;
      if (pm == undefined) return 0;
      if (pm < 0) return 0;
        /*     
              Good                              0 - 50         0.0 - 15.0         0.0 – 12.0
        Moderate                        51 - 100           >15.0 - 40        12.1 – 35.4
        Unhealthy for Sensitive Groups   101 – 150     >40 – 65          35.5 – 55.4
        Unhealthy                                 151 – 200         > 65 – 150       55.5 – 150.4
        Very Unhealthy                    201 – 300 > 150 – 250     150.5 – 250.4
        Hazardous                                 301 – 400         > 250 – 350     250.5 – 350.4
        Hazardous                                 401 – 500         > 350 – 500     350.5 – 500
        */
        if (pm > 350.5) {
        return 401;
        } else if (pm > 250.5) {
        return 301;
        } else if (pm > 150.5) {
        return 201;
        } else if (pm > 55.5) {
        return 151;
        } else if (pm > 35.5) {
        return 101;
        } else if (pm > 12.1) {
        return 51;
        } else if (pm >= 0) {
        return 0;
        } else {
        return 0;
//          return undefined;
        }
     
      }
      function bphFromPM(pm) {
      //return 0;
      if (isNaN(pm)) return 0;
      if (pm == undefined) return 0;
      if (pm < 0) return 0;
        /*     
              Good                              0 - 50         0.0 - 15.0         0.0 – 12.0
        Moderate                        51 - 100           >15.0 - 40        12.1 – 35.4
        Unhealthy for Sensitive Groups   101 – 150     >40 – 65          35.5 – 55.4
        Unhealthy                                 151 – 200         > 65 – 150       55.5 – 150.4
        Very Unhealthy                    201 – 300 > 150 – 250     150.5 – 250.4
        Hazardous                                 301 – 400         > 250 – 350     250.5 – 350.4
        Hazardous                                 401 – 500         > 350 – 500     350.5 – 500
        */
        if (pm > 350.5) {
        return 500;
        } else if (pm > 250.5) {
        return 500;
        } else if (pm > 150.5) {
        return 300;
        } else if (pm > 55.5) {
        return 200;
        } else if (pm > 35.5) {
        return 150;
        } else if (pm > 12.1) {
        return 100;
        } else if (pm >= 0) {
        return 50;
        } else {
        return 0;
//          return undefined;
        }
     
      }
 
      function calcAQI(Cp, Ih, Il, BPh, BPl) {
     
        var a = (Ih - Il);
        var b = (BPh - BPl);
        var c = (Cp - BPl);
        return Math.round((a/b) * c + Il);
     
      }
 
 
      function getAQIDescription(aqi) {
        if (aqi >= 401) {
          return 'Hazardous';
        } else if (aqi >= 301) {
          return 'Hazardous';
        } else if (aqi >= 201) {
          return 'Very Unhealthy';
        } else if (aqi >= 151) {
          return 'Unhealthy';
        } else if (aqi >= 101) {
          return 'Unhealthy for Sensitive Groups';
        } else if (aqi >= 51) {
          return 'Moderate';
        } else if (aqi >= 0) {
          return 'Good';
        } else {
          return undefined;
        }
      }
 
      function getAQIMessage(aqi) {
        if (aqi >= 401) {
          return '>401: Health alert: everyone may experience more serious health effects';
        } else if (aqi >= 301) {
          return '301-400: Health alert: everyone may experience more serious health effects';
        } else if (aqi >= 201) {
          return '201-300: Health warnings of emergency conditions. The entire population is more likely to be affected. ';
        } else if (aqi >= 151) {
          return '151-200: Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.';
        } else if (aqi >= 101) {
          return '101-150: Members of sensitive groups may experience health effects. The general public is not likely to be affected.';
        } else if (aqi >= 51) {
          return '51-100: Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.';
        } else if (aqi >= 0) {
          return '0-50: Air quality is considered satisfactory, and air pollution poses little or no risk';
        } else {
          return undefined;
        }
      }
Title: Re: personal air pollution sensor
Post by: Keith Myers on December 15, 2017, 05:05:57 PM
I've had my PA-II installed for a couple of months now. And yes, WU has integrated my sensor into my WU station data. If you click on the Air Quality link in the page for your city or your station, it goes to the air quality readings for PM2.5 and PM10 produced by my sensor. The page pulls ozone levels from the closest Air Quality Management District sensors.  When you click on the map and zoom in you will find your sensor located on the map.  There are not that many sensors so far.  I'm the only one reporting for my county and neighboring counties also have only typically one. Rural Northern California FYI.

I have seen the biggest drivers of PM2.5 pollution being produced by my neighbors fireplace/chimney smoke and what direction the wind is blowing.  The PM10 readings were greatly influenced by the huge winds we had right when I installed the sensor and massive amounts of dust and grit were blowing and also the large forest fires smoke blowing in from other areas.
Title: Re: personal air pollution sensor
Post by: azchrisf on December 25, 2017, 11:21:08 AM
Incase anyone is interested, I opened up my sensor to take a look.
I took pictures of the board and components. It's basically a cobbled together experiment...not really professional.

Pictures:
https://www.dropbox.com/sh/8h5wu03y97385ns/AAAH2s3hma7h4qTDHP4ydDoya?dl=0
Title: Re: personal air pollution sensor
Post by: Toxic on December 25, 2017, 12:54:56 PM
Interesting hardware.... Thanks for the pics
Title: Re: personal air pollution sensor
Post by: Eno on December 27, 2017, 05:59:19 PM
Incase anyone is interested, I opened up my sensor to take a look.

I guess I might as well take mine apart too.  Since it won't stay online anymore it's just a paperweight anyway. A $250 paperweight.

December 28 update:  PurpleAir responded in a timely manner to my issue and resolved it with new firmware.

And now on Dec 31 it goes offline again. F-ing A.
Title: Re: personal air pollution sensor
Post by: Keith Myers on December 27, 2017, 09:42:53 PM
Sorry to hear you have a paperweight now.  Mine has been working flawlessly.  No issues at all.  Hope that continues.  Did you attempt any warranty replacement action?
Title: Re: personal air pollution sensor
Post by: Eno on December 27, 2017, 10:44:07 PM
Sorry to hear you have a paperweight now.  Mine has been working flawlessly.  No issues at all.  Hope that continues.  Did you attempt any warranty replacement action?

Mine worked flawlessly for 35 days. It's actually working at the moment. I unplugged it for two hours, restored power, and it's up, but if the pattern of the last few days holds, it will be offline by morning.

I learned a lot about my router though and improved my home network.  I specified 802.11 n only mode, determined the best channel, and got the RSSI for the device down from -74 dBm to 58-61 dBm.

I don't see anything about a warranty in their Terms and Conditions.  I sent them an email yesterday describing the problem though.
Title: Re: personal air pollution sensor
Post by: Keith Myers on December 28, 2017, 04:41:06 AM
It took about a week for a reply from them for a setup difficulty question I posted after I received the unit. I figured it out on my own in a day.  But their reply did in fact match everything I did to get the system up and running on my network.  Have a feeling the company is just a few individuals and the images of the internal construction lends to that observation of basically a hobbyist or kickstarter type of product.

There still is a problem with the map location of my sensor on my account page after login.  I think it has never been updated from the location of the phone I used to get the sensor onto my network.  When you use the US map of sensors and zoom to your location, it is correct though.  The sensor location on the map from the link in Wunderground is correct also. The software seems to still be in infancy.

I make specialized products of my own for hobbyist use.  I back my products unconditionally.  Just the way I feel about the quality of product I produce.

As I stated, not a lick of trouble with my unit.  Been reporting my local air quality for a couple of months now.  Felt the air quality sensor would be a nice addition to my weather station.
Title: Re: personal air pollution sensor
Post by: tractor on December 28, 2017, 05:50:09 PM
I've had my PA-II installed for a couple of months now. And yes, WU has integrated my sensor into my WU station data. If you click on the Air Quality link in the page for your city or your station, it goes to the air quality readings for PM2.5 and PM10 produced by my sensor. The page pulls ozone levels from the closest Air Quality Management District sensors.  When you click on the map and zoom in you will find your sensor located on the map.  There are not that many sensors so far.  I'm the only one reporting for my county and neighboring counties also have only typically one. Rural Northern California FYI.

Hello, thanks for your post. I am trying to integrate a Purple Air sensor into my existing Davis Instruments PWS that is shown on Weather Underground. I don't see an option on any WU PWS page that shows AQI, but I might be missing something obvious. Do you mind sharing your PWS Station ID so I can look at how it works? I can't have two PWS for one location as our PWS site is very active as far as viewership.

WU will not reply to emails on this matter, so any info you have would help.
Thanks!
Title: Re: personal air pollution sensor
Post by: Eno on December 28, 2017, 05:56:17 PM
Sorry to hear you have a paperweight now.  Mine has been working flawlessly.  No issues at all.  Hope that continues.  Did you attempt any warranty replacement action?

Mine worked flawlessly for 35 days. It's actually working at the moment. I unplugged it for two hours, restored power, and it's up, but if the pattern of the last few days holds, it will be offline by morning.

I learned a lot about my router though and improved my home network.  I specified 802.11 n only mode, determined the best channel, and got the RSSI for the device down from -74 dBm to 58-61 dBm.

I don't see anything about a warranty in their Terms and Conditions.  I sent them an email yesterday describing the problem though.

PurpleAir responded to my issue and then they installed new firmware that looks like it solved the problem. Nicely done PurpleAir!  =D&gt; =D&gt;
Title: Re: personal air pollution sensor
Post by: Keith Myers on December 28, 2017, 06:15:31 PM
@Tractor, the AQ sensor doesn't show up on your personal PWS page, but rather for your city location. If you look for your local weather location, there is a Air Quality section about middle of the page, in between the Pollen and UV Index reports.  If you click on the Air Quality box, it takes you to the Air Quality page where it shows the US map with which you can zoom in on your location.  Down at the bottom of the page there is a box labelled "Nearby Pollution Monitors".  That is where my Purple Air PAII is listed as:
IDLOCATIONTIMETYPELEVEL (ΜG/M3)
LCAORLAN1Orland, CA3:08 PMPM10 9.49
LCAORLAN1Orland, CA3:08 PMPM2.5 9.46
https://www.wunderground.com/health/us/ca/orland/95963?cm_ven=localwx_modaq (https://www.wunderground.com/health/us/ca/orland/95963?cm_ven=localwx_modaq)

If you just installed your monitor, I think it takes about a week for Purple Air to export your sensor ID and location to Wunderground to be integrated.
Title: Re: personal air pollution sensor
Post by: tractor on December 28, 2017, 07:01:23 PM
Thank you!
I hope that Weather Underground would consider duplicating that data on the PWS page. As helpful as it is to have the AQI for the general geographical area, I use WU's weather stickers and people click on the sticker from our homepage and then they can see more detailed data such as UV, etc. It would be great if they could just add a field on the PWS with the current AQI, and maybe a little bar with an arrow next to the number to reflect what a safe range for AQI is. Seems like they already have the data available and shouldn't be too hard to add it to the PWS page. It would be great for tracking historical data also like you can do with other measurements.
Title: Re: personal air pollution sensor
Post by: Keith Myers on December 28, 2017, 07:10:17 PM
Yes, exactly my wishes too.  As said, all the exported data is on that geographical location. Shouldn't be difficult to integrate into the PWS page for a station.  There aren't that many elements on the page, should be room to squeeze one more in.
Title: Re: personal air pollution sensor
Post by: Skywatch on December 28, 2017, 11:53:21 PM
Wish Wunderground would have some "at a glance" PA display on the dashboard that perhaps linked to a detailed air quality page. Even having a separate PWS or PAQM (Personal Air Quality Monitor) page I'd like some linkage with my PWS.

Title: Re: personal air pollution sensor
Post by: azchrisf on December 29, 2017, 05:14:53 AM
OK guys, for you website creators out there, I have worked up a PHP script that grabs the AQI data from JSON. It uses the code supplied by them and rewritten for PHP.

Format the script for your site, but the basic work is done. You can add more variables for things (v1, v2, v3 etc. are for things like Short term, 30 minutes, etc.)

Enjoy!

Title: Re: personal air pollution sensor
Post by: Keith Myers on December 29, 2017, 12:51:59 PM
Thanks, that script will go a long way for PWS owners who report the data on their own hosted site.
Title: Re: personal air pollution sensor
Post by: Toxic on December 29, 2017, 12:53:23 PM
Is it possible to get any data from the unit itself?
Title: Re: personal air pollution sensor
Post by: azchrisf on December 29, 2017, 01:14:08 PM
Is it possible to get any data from the unit itself?

Enter the IP of the unit on your network, it has a webpage.
Title: Re: personal air pollution sensor
Post by: Toxic on December 29, 2017, 01:24:08 PM
Just curious I don't own one as yet. Are you able to SSH into it?
Title: Re: personal air pollution sensor
Post by: R_o_B on December 30, 2017, 05:31:08 AM
Is it possible to get any data from the unit itself?
Yes it is possible - as long as you know the IP address of the sensor. Unfortunately, locally, only the data from one channel is available (I have not found a way to access the second channel locally, even after writing many unanswered messages to Adrionics Llc for assistance).

For example, if the PurpleAir sensor local IP address is '192.168.1.15', then, (using PHP) a cURL download or a 'file_get_contents' at 'http://192.168.1.15/json' will produce a JSON file (that JSON file should be saved to disk). The data from that JSON file can then be extracted using the 'json_decode()' function - the data will be in an array.

The values in the array are 'particulate matter' numbers - the useful numbers are those found at 'pm2_5_atm' (2.5 ug/m3) and at 'pm10_0_atm' (10.0 ug/m3).

Then, those numbers have to be processed in order to calculate the air quality index. More information on how the air quality index is calculated can be found on the Wikipedia Air quality index (https://en.wikipedia.org/wiki/Air_quality_index) page.
Title: Re: personal air pollution sensor
Post by: Toxic on December 30, 2017, 05:54:53 AM
Is it possible to get any data from the unit itself?
Yes it is possible - as long as you know the IP address of the sensor. Unfortunately, locally, only the data from one channel is available (I have not found a way to access the second channel locally, even after writing many unanswered messages to Adrionics Llc for assistance).

For example, if the PurpleAir sensor local IP address is '192.168.1.15', then, (using PHP) a cURL download or a 'file_get_contents' at 'http://192.168.1.15/json' will produce a JSON file (that JSON file should be saved to disk). The data from that JSON file can then be extracted using the 'json_decode()' function - the data will be in an array.

The values in the array are 'particulate matter' numbers - the useful numbers are those found at 'pm2_5_atm' (2.5 ug/m3) and at 'pm10_0_atm' (10.0 ug/m3).

Then, those numbers have to be processed in order to calculate the air quality index. More information on how the air quality index is calculated can be found on the Wikipedia Air quality index (https://en.wikipedia.org/wiki/Air_quality_index) page.
Thanks for the info

Sent from my ONEPLUS A3003 using Tapatalk

Title: Re: personal air pollution sensor
Post by: azchrisf on December 30, 2017, 11:09:54 AM
I finished the script. I've moved it to it's own thread here:
https://www.wxforum.net/index.php?topic=33482.0
Title: Re: personal air pollution sensor
Post by: mmorris on January 11, 2018, 07:04:08 AM
Unbelievable I'm still waiting to receive my PurpleAir any one else waiting?
Title: Re: personal air pollution sensor
Post by: azchrisf on January 11, 2018, 07:20:55 AM
Yes me too, I emailed them and they are still blaming power supplies.
Title: Re: personal air pollution sensor
Post by: Toxic on January 11, 2018, 07:51:07 AM
Yes me too, I emailed them and they are still blaming power supplies.

I was told 3 days ago the issue was a newer sensor on channel A was not working with older firmware and they had to write new firmware for it. I was told they were close to finishing this and would hopefully ship by the end of the week.
Title: Re: personal air pollution sensor
Post by: Toxic on January 11, 2018, 02:57:27 PM
We now have a new forum for Air Quality Sensors!

Thanks Ken!

Sent from my ONEPLUS A5010 using Tapatalk

Title: Re: personal air pollution sensor
Post by: Toxic on January 12, 2018, 04:05:48 PM
Unbelievable I'm still waiting to receive my PurpleAir any one else waiting?

Yes me too, I emailed them and they are still blaming power supplies.

just got my Email saying it was shipped today!
Title: Re: personal air pollution sensor
Post by: Toxic on January 22, 2018, 11:11:41 AM
Yes me too, I emailed them and they are still blaming power supplies.

Picked mine up from the post office this morning so they are ready to ship ;)
Title: Re: personal air pollution sensor
Post by: mmorris on January 25, 2018, 06:34:32 AM
Still waiting :!:
Title: Re: personal air pollution sensor
Post by: azchrisf on January 25, 2018, 08:18:46 AM
Same here

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Title: Re: personal air pollution sensor
Post by: azchrisf on January 26, 2018, 06:36:55 PM
Well I got a ship notification finally.

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Title: Re: personal air pollution sensor
Post by: mmorris on January 26, 2018, 11:06:11 PM
Today I got a shipping notification finally.
Title: Re: personal air pollution sensor
Post by: Toxic on January 27, 2018, 10:12:04 AM
Good news then :)

Sent from my ONEPLUS 5T using Tapatalk

Title: Re: personal air pollution sensor
Post by: mmorris on January 29, 2018, 09:40:07 PM
Mine showed of in the mail box now just have to wait for nicer weather.
Title: Re: personal air pollution sensor
Post by: Jαchym on January 30, 2018, 01:07:48 PM
Unfortunately, so far there are no accurate personal air quality monitors. The only accurate ones are professional, large, very expensive units. These budget versions are to a large extent affected by meteorological conditions and there are many other issues which make the error levels very high. I wanted to buy one some time ago because I live in a large city and it would be interesting. But after doing some research it turned out none of these are really accurate. Especially with certain compounds. The manufacturers of these will be very hesitant to admit it, although they know it very well.
Title: Re: personal air pollution sensor
Post by: RXB2 on January 30, 2018, 01:43:19 PM
The only accurate ones are professional, large, very expensive units. These budget versions are to a large extent affected by meteorological conditions.
So BAMS and TEOMs are not affected by meteorological conditions?


none of these are really accurate. Especially with certain compounds.
Most of the posts above are about PurpleAir's PM sensors. They don't measure any compounds, only particulate matter.
Title: Re: personal air pollution sensor
Post by: Jαchym on January 31, 2018, 10:51:52 AM
Yes, even those that measure PMs are not accurate. During some conditions they can be, but you never know that and so it is not something you can count on.
Title: Re: personal air pollution sensor
Post by: mmorris on January 31, 2018, 12:25:41 PM
Nothing but death and Taxes is a sure thing. Even the official equipment may be only right part of the time. 
Title: Re: personal air pollution sensor
Post by: azchrisf on January 31, 2018, 01:22:06 PM
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 site.

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Title: Re: personal air pollution sensor
Post by: Jαchym on February 01, 2018, 08:24:49 AM
It is the most accurate personal air quality sensor, but... but the other ones often have errors over 100%. This one only 30-50%.... which IMHO is still a LOT

Quote
PA-II had the highest correlation with measurements made in side-by-side tests in the field with the expensive commercial-grade sensors used by EPA. Thus, when a change in PM2.5 levels occurred, the PA-II did the best job of tracking the change. However, the PA-II tended to have a high bias in these field tests, typically overestimating the PM2.5 levels by 36 - 48%.

So yes, excellent for the price, but in general, not very good.
There is more pages describing this.
Title: Re: personal air pollution sensor
Post by: Aardvark on February 01, 2018, 04:50:42 PM
I have thought about Purple Air , the personal sensor, but going to wait a bit longer.  Finances.

I bought two air purifiers that have sensors that speed up the fan when the air is not so great (Winix 5300*2)/  I got my daughter one because she has asthma.  Being the 38 year old she is,  she farted near the sensor, the indicator went from normal to deep red, the fan roared to action as we laughed.   I am guessing that if a toot can trip the sensor, probably someone could actually produce one that theycould get the readings directly.

What of late really bothers me is that we buy things, but have to have a web or phone connection to get the data from it. Bloomsky is a perfect example, no way to get pictures or the data, but have to rely on servers working.   I guess that is partly why I am going to wait on the Purple Air, but you know I want one
Title: Re: personal air pollution sensor
Post by: Forever on February 01, 2018, 05:45:04 PM
You can access the data directly from the PurpleAir using it's IP/jason. This will be important when their site is down like it is now.
Title: Re: personal air pollution sensor
Post by: azchrisf on February 01, 2018, 06:02:16 PM
Wonder what's going on, they've been down a couple times in the last week.
And they offer a model with a SD Card so you can have local data too.

Also, I've found it pretty good at sensing pollution. For what it is, I think it's pretty good.
Also, I think the inventor was working on getting those numbers down, but of course a $250 item will never compare in accuracy to a $25K machine. It's one of those "good enough" thing I guess.
Title: Re: personal air pollution sensor
Post by: Toxic on February 05, 2018, 05:57:43 PM
Is it possible to get any data from the unit itself?
Yes it is possible - as long as you know the IP address of the sensor. Unfortunately, locally, only the data from one channel is available (I have not found a way to access the second channel locally, even after writing many unanswered messages to Adrionics Llc for assistance).

For example, if the PurpleAir sensor local IP address is '192.168.1.15', then, (using PHP) a cURL download or a 'file_get_contents' at 'http://192.168.1.15/json' will produce a JSON file (that JSON file should be saved to disk). The data from that JSON file can then be extracted using the 'json_decode()' function - the data will be in an array.

The values in the array are 'particulate matter' numbers - the useful numbers are those found at 'pm2_5_atm' (2.5 ug/m3) and at 'pm10_0_atm' (10.0 ug/m3).

Then, those numbers have to be processed in order to calculate the air quality index. More information on how the air quality index is calculated can be found on the Wikipedia Air quality index (https://en.wikipedia.org/wiki/Air_quality_index) page.

looking at the local ip/json looks like it has both channel values listed.

Title: Re: personal air pollution sensor
Post by: R_o_B on February 06, 2018, 03:51:22 AM
looking at the local ip/json looks like it has both channel values listed.
Could you please tell me how you have reached that conclusion? The local data is accessed by using the following link:
Code: [Select]
http://{sensor IP address on the local/internal network}/jsonsuch as:
Code: [Select]
http://192.168.1.###/jsonThe resulting JSON file contains only the data from channel #1.

If you have another way of getting the data for both channel #1 and channel #2 directly from the PurpleAir sensor (and NOT downloaded from the Thingspeak database), please, pass along your secret - I have asked the designer behind the PurpleAir sensor that exact question about six months ago and I have yet to received a reply...  :roll:
Title: Re: personal air pollution sensor
Post by: azchrisf on February 06, 2018, 04:03:26 AM
R_o_B I believe Toxic or Forever answered this question by providing a sub-script of mine in the PHP/Website subforum.
Title: Re: personal air pollution sensor
Post by: Toxic on February 06, 2018, 05:18:28 AM
Could you please tell me how you have reached that conclusion? The local data is accessed by using the following link:

the json data: just the pm values:

Code: [Select]
"pm1_0_atm_b":0.32,
"pm2_5_atm_b":0.24,
"pm10_0_atm_b":0.08,
"pm1_0_cf_1_b":0.32,
"pm2_5_cf_1_b":0.24,
"pm10_0_cf_1_b":0.08,
"p_0_3_um_b":50.53,
"p_0_5_um_b":12.37,
"p_1_0_um_b":1.24,
"p_2_5_um_b":0.05,
"p_5_0_um_b":0.08,
"p_10_0_um_b":0.08,
"pm1_0_atm":0.22,
"pm2_5_atm":0.02,
"pm10_0_atm":0.02,
"pm1_0_cf_1":0.22,
"pm2_5_cf_1":0.02,
"pm10_0_cf_1":0.02,
"p_0_3_um":86.28,
"p_0_5_um":23.57,
"p_1_0_um":4.33,
"p_2_5_um":0.24,
"p_5_0_um":0.43,
"p_10_0_um":0.26,

are you telling me the _b are not b channel?
Title: Re: personal air pollution sensor
Post by: Eno on February 10, 2018, 06:50:36 PM
Maybe try

https://www.purpleair.com/sensorlist?showaverages=true

 :idea: