Build a cheap air quality meter using ESPhome, Home Assistant and a particulate matter sensor

This article will provide a walkthrough of how you can build a Particulate Matter Air Quality meter that integrates with your Home Assistant for under 20$, without any soldering or coding skills needed.

The sensor will provide multiple air-quality measurements directly visible in Home Assistant.

After seeing all kinds of air purifiers in the market, like the one from Xiaomi and Philips. I got interested in the topic air quality. First, I needed to learn more about how and what to measure, followed by actually measuring the air quality in my home. I don’t want to buy a air purifier if the quality of the air in my home is not bad. But how do you measure air quality?

What is a Particulate Matter sensor?

My search started with looking for a particulate matter sensor. A particulate matter sensor measures tiny particles or droplets in the air that have a specific size in microns or micrometers (µm). Like inches, meters and miles, a micron is a unit of measurement for distance. There are about 25,000 microns in an inch.

Particulate matter is the sum of all solid and liquid particles suspended in air many of which are hazardous. This complex mixture includes both organic and inorganic particles, such as dust, pollen, soot, smoke, and liquid droplets. These particles vary greatly in size, composition, and origin.


Particulate matter (PM) is generally classified into two main size categories: PM10 and PM2.5. As an example, the particulate classified as PM2.5 is the size of 2.5 µm and would be thirty times smaller than that of a human hair.

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