personal-site/content/Custom Air Quality Monitor.md

Title: Custom Air Quality Monitor Date: 2025-01-13 Category: Creations Summary: An air quality monitor made from sensor modules. Image: airmonitor1.jpg xTags: feed

I made custom air quality monitors to track the air in my kitchen, living room, and bedroom. They use sensor modules that detect PM2.5, PM10, CO₂, VOCs, Light level, pressure, temperature and humidity. The data is sent to my Sensors database once per minute.

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The modules connect to an ESP8266 Arduino over I²C and UART serial. They are mounted on press-fit pegs to a 3D printed base plate I designed in FreeCAD.

The sensors used are:

• HPMA115S0 - Particulate Sensor
• Adafruit SCD-30 - NDIR CO2 Temperature and Humidity Sensor
• Adafruit BH1750 - Light Sensor
• Adafruit SGP40 - VOC Sensor
• Adafruit LPS22 - Pressure Sensor

The light data is used by my home automation system to know when it's night time so that motion sensors turn lights on. I also learned that the CO₂ level in my bedroom was doubling from 650 ppm to 1251 ppm overnight while I slept. This is bad since high CO₂ concentration affects sleep, so now my automation system turns the furnace blower on while I sleep.

Before running the blower automatically (24 hour graph, CO₂ is the blue line):

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After:

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