Recently, I began to work on DIY-ing my own air filter (a blog on this will be coming out soon). However, I needed a way to measure the effectiveness of said filter, so I decided to invest in an air quality monitor. In the interest of fully understanding all parts of this DIY, I decided to do a bit more of in-depth reading into how air quality monitors actually work.
The monitor I decided to use (linked above) claims to measure the “environment PM2.5, PM1.0, PM10” as well as “the AQI.” Well, what do these terms mean? “PM” is an abbreviation for the phrase “particulate matter,” and the numbers following refer to the diameter of the particle itself. So, PM1.0 means the level of particulate matter with a diameter equal to or less than 1.0 micrometer, and so on.
This particular sensor uses the laser scattering principle — that is, a laser is used to radiate particles in the air, and then the scattered light is collected.
This diagram demonstrates how exactly air monitors detect particles at a very basic level. The size of the breaks (caused by the particles) in the laser also allows for the recording of how many particles at each size are present. This classification is important because particulate matters of different sizes can have different effects on the human body. Generally, the smaller the size of the particle, the greater the risk it poses to human health. Smaller particles (such as PM1.0s and PM2.5s) tend to stay in the air longer than heavier particles, and have an easier time of traveling from the nose to the lungs, dramatically increase the possibility for respiratory illnesses and heart attacks.
After the level of each group of particulates is calculated, the AQI, or air quality index, is calculated. The AQI is an indicator of air quality that runs from 0 to 500 and is divided into six categories, ranging from good to hazardous. The higher the AQI, the worse the air quality is. You can read more about what each category means here.
Stay tuned for my upcoming blog on how to actually put together an air filter!