CO2 (Carbon Dioxide)
CO2 (Carbon Dioxide) is a dangerous gas for humans. In high concentrations it can produce vertigo, headache, high blood pressure, fast heart rate, suffocation and loss of consciousness.
It is advisable to be careful with it, especially in places where there are many plants since they expel it in its breathing process.
I have spent years with the intention of having CO2 WiFi sensors in the house, which allow triggering alarms when the levels are too high or performing other actions.
About a year ago, I installed a NetAtmo weather station (which I didn't need since I have a Davis Vantage PRO2) and one of the good things it has is an indoor CO2 sensor.
The truth is that I do not know how accurate the CO2 sensor of the NetAtmo station is but from the beginning I have wanted to check it.
The NetAtmo station interior module is installed in the room (providing data on temperature, humidity, luminosity, sound pressure and CO2 in the room) but I want to be able to measure CO2 in more places and, especially, make specific measurements to see if we are "Endangered", for example measuring CO2 levels in different bedrooms while we sleep.
Until relatively recently, CO2 sensors were very expensive and required calibration that was not normally available to hobbyists. This has changed quite a bit in recent months with the appearance of some inexpensive sensors that are easy to use and that are already pre-calibrated at the factory.
Recently I started looking for information about the "state of the art" of these things, to see if it was finally time to tackle the issue of sensors, and I found several quite interesting sensors. Among those I came across was one that drew my attention to the others, the MH-Z19.
WiFi CO2 detector
The detector consists of an ESP8266 microcontroller module with integrated WiFi and a CO2 sensor.
You can find more information about mounting the detector in this blog post