Indoor Air Quality Covid 19 Transmission Risk Indicator

The risk of Covid 19 infections depends highly on the characteristics of the indoor air, especially the rate of ventilation and the temperature and humidity inside the room.

We have recently updated the AirGradient dashboard with an easy-to-understand Covid 19 transmission indicator which gives qualitative indications like “very low”, “low”, “high” etc.

This indicator takes into consideration the following factors:

  • CO2: Carbon dioxide is a great indicator of the ventilation performance of a room and the number of people inside a room. It is recommended to keep the CO2 below 750ppm for low transmission risks. Our indicator calculation starts to consider an elevated risk at 750ppm and progressively increases the higher the CO2 levels.
  • Temperature: The Corona Virus survives longer the lower the temperature starting from about 25C. Therefore we start considering an increased risk at temperatures below 25C. With a considerably higher score with temperatures below 10C.
  • Humidity: Low humidity increases the infection risk due to mainly two reasons: (a) Your repository system (e.g. your nose) dries out and thus is more susceptible to receiving viruses and (b) Aerosols become lighter and thus stay in the air for longer. We are therefore considering low humidity in the Covid 19 indicator at relative humidity <30%.

Note of Caution: This score only gives you an indication based on the indoor air and should be used with caution. The score e.g. does not know if people wear masks and if social distancing is observed.

However, it can also give valuable information, e.g. for a school to see how well classrooms are ventilated and works very well together with our CO2 traffic light.