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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Bellfire home automation project

This article provides you with an overview and links of all articles published around the fireplace project that was presented during the Home Assistant Conference 2020.


View Automate Everything! How to make your stupid device smart on Notist.

Introduction articles

The steps

Shopping list

  1. The ESPboard: ESP8266 board or ESP32 if you also want to use Bluetooth features on
  2. The 4 channel relay board. Make sure you select the 5V version The relay: 5v relay board
  3. If you don’t want to solder order:
    – Mini breadboards
    – Dupont cables male-female

Introducing ESPHome

This article is part of the Make your Bellfire fireplace smart project that I presented during the Home Assistant Conference 2020.

In the previous article, we introduced ESP boards and Relays that will help to switch the Bellfire fireplace pins of the controller. Now we need to control software that connect the ESP to Home Assistant and that can control the relays using the ESP GPIO pins. We are going to do this with an ESPHome.

ESPHome — ESPHome

ESPHome is a system to control your ESP8266/ESP32 by simple yet powerful configuration files and control them remotely through Home Automation systems like Home Assistant.

ESPHome is amazing, it’s extremely powerful and, more important very stable. It has never failed me. The integration with Home Assistant is seamless, including autodiscovery within Home Assistant and one-click configuration.

If you want, you can build advanced sensors with it. The good thing is that sensors are supported natively by ESPHome and can be used by easy configuration. The possibilities with ESPHome and Home Assistant are endless; the blocking factor is your own imagination.

Key features

  • Easy to work with, no programming needed
  • Seamless integration with Home Assistant
  • Over-The-Air flashing of the firmware
  • Supports a long list of devices.

We’ll use ESPHome to connect the ESP to Home Assistant and to control the relays using the GIO pins.

So we have Home Assistant, a relay, a ESP board, ESP home and a fireplace…. How is this all going to work together? I’m going to tell you that in the next article.