Fighting Smoke with Open Source

I am a development lawyer with Akamai and a great advocate of the Open Source initiative. That’s why today I’m going to tell you a story about how a normal person like you or me can influence things with a little bit of good will and a pinch of open source.

In the early morning of the 16th. August struck about 2,500 lightning bolts in the San Francisco Bay Area, where I live, and 200 in less than 30 minutes. Over the next 72-96 hours, more than 12,000 lightning strikes were recorded in Northern California, causing more than 500 forest fires, many of them very serious. Today, in just a few weeks time, the air quality on the west coast has deteriorated due to an enormous amount of smoke.

When all this happened and my neighborhood was covered in smoke and ashes, my first thought was what I could do to protect my family and the people in my community from all this unhealthy air.

I looked at commercial air purifiers, but most of them were out of stock, and frankly, I’m the kind of guy who loves crafts and construction, so I decided to take the road myself. I wanted to build something cheap that could be used for other purposes, and then share my results with others (as I usually do with technology)!


I knew I needed two things:

  1. Method for filtering vapours (air cleaner).
  2. Indoor air quality monitoring (air monitor)

Air purifier

I did some research on do-it-yourself air cleaners and discovered that certain types of air filters used in heating and cooling of houses (also called HVAC) can filter out smoke particles. These air filters have a rating of at least FRP 10 / MERV 13, with higher FRP and MERV values indicating better quality and the ability to capture the smallest air particles.

So I decided to buy an MERV 13 filter first. The filter can be used in heating, ventilation and air conditioning systems, but it is a slow process. If there is a lot of smoke, it is best to use an air cleaner, which is basically a fan with a special filter. But then I searched the internet and found a great video explaining how to build it with a cheap box fan and an HVAC FPR 10 filter. He also explains how this do-it-yourself air purifier compares to commercial air purifiers that cost hundreds of dollars.

So I ordered fans and filters from The Home Depot and they were delivered in one day! Then I simply used a transparent packaging tape to stick the air filter on the back of the fan.

Pay attention: Note the arrow on the side of the filter, which explains the direction of air flow. But if you don’t read the instructions, you still have a 50% chance of success!

Air monitors

Now the air monitor is an extra step and it’s not really necessary, but it’s perfect if you want an accurate indication of the immediate air quality. You can also use sites like to check the quality of the outside air and operate an air cleaner when the quality of the outside air is poor. If you prefer a low-tech approach, you can always look at the sky and use your sense of smell to recognise signs of smoke. However, it is important to know that many harmful air pollutants are odourless and invisible to the naked eye.

Personally, I just like to measure and improve things, and I wanted to be able to check the air quality to know if the air purifier really works and also to know how long I need to work with my air purifier to improve the air quality. As I said before, I’m an open source fan, so I’ve put together some of my favorite tools to set up an automated air monitoring system.

Since a few years I work with sensors and PLC’s to monitor a lot of things in my house. For this I use the Raspberry Pi tablet, which I made and run under the open source software OpenHab for home automation.

For this project I wanted to build something simple with what I already had at home:

The next thing I had to do was to send the SDS011 sensor to GitHub, and I found an example Python code that I could apply in 5 minutes (don’t you like GitHub?).

I adapted the Python code by adding a code that makes it possible to print the particle measurements on the SenseHAT LED array using color coding. The measurement is printed in green if the air quality is good, in yellow if it is moderate and in red if the air quality is poor.

I have also added code to record the temperature, pressure and humidity measurements of the SenseHAT sensors and print these measurements both on the Pi console and in the JSON format file available on the Pi webserver (/var/www/html/aqi.json), which allows you to easily display the measurements as a graph with Grafana or a visualization tool of your choice.

You can copy the code I use from my GitHub repository.

Thanks to this code I check the effect of two of my air purifiers (one for each floor of my house), and after a few weeks of using the system I can confirm that it works quite well!

Normally I check the air quality when I wake up with Pi’s air quality control system, and when I see red, I just turn on the filter until the indicator turns green. Another tip: Pi shuts off the power so you can move it to other rooms.

At maximum fan speed it takes about 30 minutes to bring the air quality in a large bedroom with a closed door to a good level, but this time depends on the fan speed and the size of the room.


Below you can see the Grafana dashboard I installed, which shows a graph of the air quality of the last 7 days.

Here is an increase in this graph, which shows the increase of the solids content (pm2.5) in dark green. Values below 50 are considered good.

Open Source has changed the world by enabling billions of people to share knowledge and work together for common development. I am constantly learning and sharing new things with my friends, family and team at work, using new open source tools.

The Akamai team and I hope that this position can help people suffering from poor air quality in all parts of the world. Let us know if you are working on open source projects to improve your daily life!

Tweet @jjaviergarza please and let me know what you think. And don’t forget: Share what you know and learn what you don’t!


GitHub: Do-it-yourself code for air quality monitoring and instructions for air filter installation

*** This is a syndicated blog from a network of Akamai security bloggers, written by Javier Garza. Read the original message at

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