This is the second article in the “Dust” – Series. This time i will review what options are the to measure it. Those are all the posts:
In the previous post I explained why is it important to know the dust levels.
In order to take an action, you have to know what is the current indoor and outdoor situation. The set if actions can be:
- Go outside and do sports
- Go outside, avoiding sports
- Go outside of the city
- Stay at home
- Stay at home and run a purifier
- … your own…
Public Services for Outdoor AQI
There are lots of Air Quality Monitoring stations out there that stram data online. In case you leave nearby such station there may be no need to explicitly measure the outdoor dust levels around you.
|The best public service i have discovered so far is aqicn.org. For each city it supports it lists some of the key indicators:
Sadly, as it can be seen some countries are not reporting AQI Data. And in the others – it is limited to major cities.
The nice thing is that it also takes meteorological information about Temperature/Humidity/Pressure/Wind and gives you an AQI forecast. This way you can plan upfront if you will need to take actions to avoid air pollution in the next couple of days.
Usually the values are averaged, so this means at Saturday i should be able to measure levels above 200 ug/m3 at certain times.
Measuring Dust on your own
In all cases where you can not obtain public data about Dust Levels (e.g. at home), you can measure it on your own. Depending on the quality of the measurement you like, depth of your wallet and time you want to spend – there are different solutions.
1. Beta attenuation monitoring (BAM) Stations ( >5000€)
|Official Measurement stations look like this. They cost 1000s of Euro and are very accurate. They are the ones used to measure and report official values for City Dust Pollution as reported by the aqicn.org site and other places. Several years ago they were the only source of information.
Luckily with the advancement of technology, now smaller and hundreds time cheaper modules are available. They are almost as accurate as those one. The low price allows the creation of lower-cost consumer grade devices.
2. Dylos DC1000 Pro ( 300€ )
|The Dylos DC1000 Pro is a very precise device that is often used as a reference when comparing lower-priced sensors. It delivers quality close to the one of the BAM stations for 10+ times lower price. Still it’s price is quite high, it isn’t too smart. But it does it’s main competency pretty well. A good review of its features can be found here.|
3. Consumer Oriented Air Quality Monitors (150-200€)
While there are quite a few other commercial devices in the range 150-200€ (Foobot, Awair, Netatmo, etc). The job they do well is great marketing, very consumer friendly (mobile and online apps) and nice packaging. The sensors they use are not necessary of best quality and precision. And the majority of the money they cost goes to those features. In this blog I would like to rather explore other options that deliver similar or better functionality.
4. vThings – Dust Monitor (65€)
|The vThings – Dust Monitor is based on a high quality Laser Dust Sensor (PM2005 from Cubic Gas Sensors). While it lacks the consumer friendliness of the higher priced devices you can use it to report data to a variety of online services or home automation systems via HTTP, MQTT or RF 433/315. Additionally it can be equipped with a CO2 Sensor and Temperature/Humidity/Pressure Sensor to make it a full fledged environmental monitor.|
5. Sonoff SC – Enviromental Monitor (20€)
|The Sonoff SC was released end of 2016 and is indeed a revolution in the low-priced Air Quality Monitoring niche. It makes use of the Sharp GP2Y1010AU0F Optical Dust Sensor (click here for a nice performance review of this sensor). The sensor allows you to “count” particles and then based on this estimate the ug/m3 value. The Sonoff device comes with a nice app and WiFi connectivity. As well as Temperature/Humidity measurement, VOC, Ambient Sound and Light.
Funny enough – all those parts have been used in the last years by lots of DIY enthusiasts to build their own Cheap Home Monitoring stations
There are a plethora of instructables and other wire ups like – “Build your own WiFi Thermometer for 5$, etc) That require extensive electronic and programming skills.
Now Sonoff combines all of this, puts it into a nice enclosure and adds a low price tag. Even more it is based on the ESP8266 so eventually one could write it’s own firmware and just reuse the hardware.
It still delivers low-quality data (e.g. tells you air quality in terms of Poor, Good, Excellent). But perhaps the Dust sensor readings can be accessed in raw format
At that price – this is really a bargain as buying all this stuff separately will cost you more. Not to mention the time necessary to build it
6. DIY Solutions (3€+)
Optical Dust Sensors (Counters)
Of course if you have a little spare time and some electronics knowledge you can build your own sensor. By reusing spare parts from past projects most of the expenses can be mitigated. There are several cheap sensors that rather give you an estimate of the number of particles. So you wouldn’t get an ug/m3 reading out of them. Most of them look like those ones.
People have been successful in getting some consistent results out of them by putting some additional fans. I personally had no luck. My sensor was giving too random results. The AQICN site also has nice reviews on some of the common sensors. Another good thing good thing about them is that there are tons of discussions and examples – how to make them run.
Laser Dust Sensors (15€ – 40€)
In the last couple of years the Laser Dust Sensors have become quite popular and cheap. You can find them in the range 15€ – 40€. Most of them are interfaced via I2C and the most popular of them already have Arduino Libraries. An important aspect of them is that all of them have built-in fans to improve air flow and accuracy. Sadly – those fans emit noise, which especially in quiet bedrooms can be heard. Usually their measurement interval is 10-30 seconds. So if you keep measuring once per hour or so during the night – this would not be too bad perhaps.
Those sensors are rated at accuracy +/-15ug/m3 (<100ug/m3) and +/-15% (>100ug/m3)
| Plantower PMS 5003
In my own vThings – Dust Monitor I selected the Cubic 2005 which has been quite reliable. I haven’t compare it against other sensors though. Sadly most of the reviews of sensors on the AQICN site are either for good sensors that are no where to be found or for sensors avaiable on aliexpress, but with low quality.