Epidemiology

The COVID-19 virus family is full of surprises, all of them bad. This note briefly summarises one of the most surprising features, and my hypothesis concerning this feature. Here are the three basic facts: We breathe out more CO2 than we breathe in, and so the more exhaled breath there is in a room, the more CO2 there will be. During COVID-19 this became a practical way to find rooms where ventilation was failing and airborne infection risk was rising. A 2024 Nature Communications paper ↗ found that in laboratory aerosols, moderately elevated CO2 also helped SARS-CoV-2 remain infectious. In other words, the virus prefers stale air - a big warning for us all to get outside and/or inhabit well-ventilated buildings. ...

The Active Heat Exchanger (AHE) research programme started as an engineering development project, and discovered first an engineering research question and then a health research question. The AHE is a retrofit ventilation device which solves the problem of there being no large-scale, long-term environmental epidemiology data for indoor air quality, despite most humans spending most of their lives indoors. The device addresses the ventilation component of sick housing while generating the continuous surveillance data the field needs. ...