http://airborne.cam helps users understand how their surroundings and day-to-day behaviour can be adapted in order to minimise the risk of indoors transmission of the SARS-CoV-2 virus. The app is based on the well-mixed approach to calculate the individual risk of infection based on the exposure time of a healthy, susceptible individual to infectious long-suspended viral particles indoors. This approach considers that individuals are far apart from each other, that is, there is no risk of short-range transmission either by large or small droplets/aerosols, nor by contact with contaminated surfaces. The basic user can change inputs such as ventilation rate, type of face covering, number of occupants, and type of activity to assess their impact on risk of infection, while more advanced features are available for the user familiar with science concerning aerosol transmission.