Engineering Clean Air for Khlong Toei: Ryan's Project

Our very own Year 13 student Ryan Murphy started teaching violin in Klong Toey slum several years ago.

He noticed many of his students are chronically sick with respiratory issues, so he set out to engineer affordable, effective and easy to assemble air purifiers for schools and poor households in the slum.

In 2025, with funding from the Rotary club, and knowledge from his physics and maths A-levels, Ryan worked with Bangkok Community Help Foundation’s volunteers and youths to build over 60 purifiers to place them in the classrooms and the most in need households in Klong Toey slum.

Over the holiday break, Ryan designed the next version of the air purifier to be even more effective and sustainable. In February, he will launch a workshop where homeless youth and community volunteers will learn to build these themselves.

All designs are open-sourced. Congratulations again to Ryan. Bangkok Prep wishes you the best of success in your project!

You can learn more from the video -  here 

We asked Ryan to share the inspiration behind this fantastic initiative — here’s what he had to say:

"I've been teaching violin on weekends at Immanuel Music School in Khlong Toei for the past two years. This January, when Bangkok's air quality hit dangerous levels – PM2.5 readings five times above WHO safety standards – my students kept coughing through their lessons.

I started wondering: what would it actually take to build an air purifier that families here could afford? Turns out, quite a lot of failed prototypes. The first version was terrible.

I tried adapting the Corsi-Rosenthal box design, but the airflow was fighting itself – loud and useless. So I flipped the fan around. Better, but the structure was flimsy.

I kept rebuilding: cubes, triangles, cylinders. I was watching YouTube videos, reading articles, messaging experts about fan curves and static pressure at 2 am, trying to understand why some designs moved air efficiently and others just made noise.

The “breakthrough” came at a hardware store. I was wandering around, frustrated, when I noticed cable trunking – those plastic channels for hiding wires. I picked one up and started thinking about the angles.

What if I cut it at 45 degrees and heated it slightly? Could filters just slide in? I tried it. They did. Perfect seal, no glue needed, completely modular. I'm not sure anyone's used cable trunking this way before, but it works.

After testing version 3 extensively, the data came together: 200-340 m³/hr clean air delivery rate, approximately 85-88% performance of commercial purifiers that cost $1,200+, all at $30 per unit. In practice rooms, PM2.5 dropped from 47 to 6 in about fifteen minutes.

I brought this idea to Friso, one of the founders of Bangkok Community Help Foundation. He was jubilant. Soon after, we ran our first workshop. It became this really fun, supportive experience – people who'd never built anything before were helping each other problem-solve, celebrating when units came together.

We built 14 that afternoon, and I realized the design didn't need to be mine – it needed to be simple enough that anyone could build it. We've distributed 60+ units now. I'm working on version 3 improvements, but honestly, I'm more curious about what happens when other people start building these.

There's a workshop in February where homeless youth and community volunteers will build 100 more units with us. All the designs are open-source, and I'm trying to spread awareness and raise support for this next phase."

To find out more and donate to this amazing cause, please click here.