The risk of being infected with the coronavirus indoors can now be determined more reliably than before using a web app. A team from the Max Planck Institute for Dynamics and Self-Organization in Göttingen and the University Medical Center Göttingen uses a refined statistical method in the web app called Human Emission of Aerosol and Droplet Statistics, or HEADS, to calculate the risk of infection via aerosols. The researchers include in their analysis the size distribution of infectious aerosols and the rate at which they settle in a room. As a result, HEADS now gives a realistic risk of infection from aerosols in enclosed spaces that are not too large. The app does not make any statement about the risk of becoming infected by droplets larger than 50 micrometers in diameter when in contact with a virus carrier at a short distance.