Air quality sensor for PM2.5 and PM10?


(Hoon Park) #1

Hi, @MatthijsJ, I am interested in the air quality sensor you had mentioned during the webcast on July 14, 2016.

I'd like to know some details about it. Some of my questions are:

  1. Are you building the sensor yourself or are you buying one?
  2. What would be the cost of it?
  3. Have you deployed it for production yet? Or, are you in the stage of building it?
  4. Is it producing reliable measurements comparing to big and expensive ones that are used by the government meteorological agencies?
  5. How did you make it compatible with TTN?

#2

Hi! Good questions, as soon as I have gathered all the answers I'll get back to you :wink:.


#3

Took a while but here are the answers:

The sensor measures NO2 and Loudness values, together with the temperature and humidity.

1. Are you building the sensor yourself or are you buying one?

The sensors are built by SODAQ, http://www.sodaq.com

2. What would be the cost of it?

Around €300 a piece.

3. Have you deployed it for production yet? Or, are you in the stage of building it?

Currently in the last building stage, we expect the first results in a few weeks.

4. Is it producing reliable measurements comparing to big and expensive ones that are used by the government meteorological agencies?

No, but multiple sensors can be calibrated against each other to give a good idea for differences in air quality between different locations.

5. How did you make it compatible with TTN?

It is built and designed to work with LoRa. There is a RN2483 module inside.

Elaborating on question 4, what motivates me is that a fine grained (mesh) network of sensors, although of lower quality, provide us with a whole new insight into the different variables that have to do with air quality when compared to only the few "high quality" sensors used by for instance the environmental agency. Especially when they are used to measure a larger area. In such cases the data from the mesh-network enriches the data gathered by the environmental agency, but is interesting on it's own accord as well.

https://www.youtube.com/watch?v=soOZRqREAXg is an example of someone riding a bike through Rotterdam with a graph that shows the measured particles. The reliability of the way this data is gathered can/should of course be questioned, but either way it does point out some very interesting effects (i.e. standing a few meters back from an intersection greatly reduces the amount of particles in the air, and probably in your lungs).

Also, check out this publication by the Dutch institute for health and environment on using different sensors to measure air quality: http://www.rivm.nl/dsresource?objectid=rivmp:302829&type=org&disposition=inline&ns_nc=1 especially page 31 with the comparison table!


(Hoon Park) #4

@MatthijsJ, Thank you very much for collecting the information.

And your approach with lots of cheaper sensors instead of one with a high price is similar to what I've been thinking too. I'll be very curious about the result of your solution once it is deployed. Because your case could be the proof that cheaper sensor approach could provide meaningful data for people.

Even though I wanted to know about PM2.5/PM10 sensors, your info gives me some idea about air pollution measurement using TTN.

https://www.youtube.com/watch?v=soOZRqREAXg was very interesting.

I hope you can share the results with us via the forum after you deploy your solution.


#5

I'm currently testing with this device. The first impression is that it's very easy to use, and I'll hope to find out how well it performs in near future. I see some mixed test results on internet so let's see how it will turn out.


#6

yes let us know how they perform :sunglasses:
they are in the sensor list
- https://www.thethingsnetwork.org/forum/t/big-diy-sensor-topic/2600/54


#7

I got weird values, and get back to something normal when I press on the casing. It must have a loose contact somewhere.

Meanwhile I also ordered its main competitor. After browsing some web pages it seems that in general this one is better, but that there's also a relatively high percentage of the individual sensors that is extremely inaccurate. So buying a few of them and compare individual differences may be useful .


#8

what are 'wierd' values ? how do you test/calibrate such a sensor .. i ordered a few to, but now i'm thinking.. 'oh (&%' :wink:

my simple idea is to detect sigarette smoke in a certain area where its not alowed to smoke.
so that's easy to test.. (however.. I don't smoke )


#9

just setups with multiple sensors of different types, where one of those shinyei sensors read almost random data. People are seriously testing that kind of stuff with professional sensors as benchmark.


#10

found some info on this forum
https://forum.mysensors.org/search/Shinyei?in=titlesposts&categories[]=all&sortBy=timestamp&sortDirection=desc&showAs=topics


#11

Compared with professional equipment:

And also:
http://www.howmuchsnow.com/arduino/airquality/

http://www.howmuchsnow.com/arduino/airquality/grovedust/


#12

' The sensor is sensitive enough to pick up cigarette smoke. '

and that's good news for my smokeNOde :sunglasses:


(Jose Marcelino) #13

This is a great resource and reviews of particle sensors too:

http://aqicn.org/sensor/


#14

Hi,

A colleague of mine has been doing some research in this area (we are a university and he is collecting air quality data from the City of Canterbury for one of the academics), he is using LoRaWAN for the network link. This is the device he is using: http://www.dylosproducts.com/dc1700.html

It has a serial output as well as an internal memory. He is taking the data it sends and passing it onto a RN24038 using a small micro-controller -- the micro buffers the packets if there are network issues. Please note if you wish to measure the count between PM2.5 and PM10 (rather than greater than PM2.5 and greater than PM10), you will need to ask the company to flash a different calibration on at time of purchase.

Because this and other similar units are optical based, they are counting the number of particles of a given diameter, rather than providing a gravimetric measurement. This means you need to provide a conversion to gravimetric units, probably by collocating it with a calibrated measuring device; such as a, beta-attenuation monitor.

Hope this helps.


#15

I hesistated a bit to post it, since it's in dutch and very locally focussed. But the report seems very interesting so I'll post it anyway.

http://www.rivm.nl/Documenten_en_publicaties/Algemeen_Actueel/Uitgaven/Milieu_Leefomgeving/Luchtkwaliteit_meten_met_sensoren

One of the things they mention is for the Dutch situation that for PM2.5 and PM10 the accepted values are hardly violated. For PM0.1 as well as 'roet' (black smoke, rather large carbon particles) are no maximum allowed values defined. I interpret that they state that it's probably of more use to measure NOx. The MQ135 sensor does so but the possible disadvantage is that it also measures other things too (like benzene or NH3).

That may not be applicable to your situation, but it may be interesting to check if there are similarities since dust is usually the first thing people think about when talking about air pollution.


#16


GP2Y1010AU0F Compact Optical Dust Sensor one of the cheapest


(Arjan) #17

What's included?

(I wouldn't mind doing the LoRaWAN stuff myself if I need to provide housing, battery, solar panel myself.)


#18

INSIDE a PPD42NS

AIRBEAM open source arduino based detector

PPD42NS - https://publiclab.org/notes/Willie/04-01-2014/field-testing-the-shenyei-pm-sensor
DSM501A - https://publiclab.org/notes/chrisbartley/04-15-2014/speck-particle-monitor


(Hoon Park) #19

Air quality sensors posted on this discussion thread are mostly indoor sensors. I've tried to find an outdoor air quality sensor based on the posted information, but could not find one.

Are there any outdoor sensors that are cheap (less than US$10) and generate good PM2.5 and PM10 measurement?

Or, what is the cheapest outdoor sensor that is small and generating good PM2.5 and PM10 measurement? Any sensor cheaper than €300 per unit?


#20

how do you know ? these are modules and off course can be used in an 'outdoor' sensor.
are you looking for a complete, weatherproof build in industrial sensor (for less then U$10?) :wink:
- http://www.dylosproducts.com/