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:

1. Why Measure Dust Levels? 
2. How to Measure? (This post)
3. Protecting your home 

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:

1. Go outside and do sports
2. Go outside, avoiding sports
3. Go outside of the city
4. Stay at home
5. Stay at home and run a purifier
6. … 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: PM10 and PM2.5 Ozone CO NO2 SO2 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€)

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.

The actual sensor costs 40€ and can be bought here, if you are on a tighter budget. The vESPrino firmware has native support for it. So making your own Dust monitor in 10 minutes is breeze.

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)

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.