Summary
After developing chronic sinusitis, which was giving me nasty headaches and mucus problems, I decided to start measuring my air quality in order to remedy my situation. What I found was an unpalatable surprise–pretty much anywhere with decent concentration of cars and trucks has bad air quality. Since I didn’t want to spend $200 on an air quality monitor, I started building my own from electronic components.
Options for sensors
There is essentially one company that makes inexpensive air quality sensors–Shinyei, a Japanese company. Their cheapest model is the PPD42NJ, which a Korean company–Samyoung copied (called the DSM501). The Samyoung model can be purchased for a few dollars on aliexpress, the Shinyei model is about 2x the cost, but seems more accurate. Shinyei also makes much more expensive sensors, with better sensitivity (the PPD60V).
First prototype
Sometime in the Fall, while searching on the internet for reasons for congested sinuses and mucus buildup, I came across air quality measurements and their effect on health, and purchased one of the Shinyei PPD42 sensors. I hooked it up to an Arduino, and started logging data on my local machine (Github here), using the code from Chris Nafis. I then started noticing trends, like air quality getting worse as people cooked and rush hour ensued, and noticed I could bring my air quality into a healthy range with an inexpensive DIY air purifier.
I built a prototype, using an Arduino, LCD screen, and the Shinyei dust sensor (instructions here). The accuracy seemed on par with the $200+ Dylos counter:
