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The web interface

The responsive web interface guides the user through through calibration & configuration. The most recent readings are displayed using visually striking gauges and the on-device data logs are made available as charts.

Up to six months of readings can be recorded in flash memory. Equally however an device can be used as part of a cloud using the MQTT publishing feature.

The on-device web interface is built using ReactJS, Charts.js & Canvas Gauges and simply invokes REST APIs made exposed by the firmware. As the packaged ReactJS app is served from a dedicated partition by the C++ core, it can be replaced entirely with any application written in JavaScript.

Why Measure CO2?

It is now accepted by major public health agencies that COVID-19 can and does spread through aerosols. See Centers for Disease Control and Prevention, World Health Organisation (WHO), European Centre for Disease Prevention and Control (ECDC).

The outside CO2 level away from combustion sources is relatively constant at ~415ppm. When a person exhales the release air containing 35,000-45,000ppm therefore the level of CO2 in an enclosed space is a proxy to the level of exhaled air which hasn't been ventilated.

If the CO2 level is too high then ventilation & filtration are the primary approaches to reducing the level of potentially dangerous aerosols.

More Information

This project relies directly on a number of open source projects, has learnt from other projects & individuals. The links below attempt a best as is possible to give full credit where it is due.