Short-range exposure to airborne virus transmission and current guidelines*

After the Spanish flu pandemic, it was apparent that airborne transmission was crucial to spreading virus contagion, and research responded by producing several fundamental works like the experiments of Duguid and the model of Wells. These seminal works have been pillars of past and current guidelines published by health organizations. However, in about one century, understanding of turbulent aerosol transport by jets and plumes has enormously progressed, and it is now time to use this body of developed knowledge. In this work, we use experiments and simulations of droplet-laden turbulent puffs emitted during sneezes in different environmental conditions. We consider the same emission and we change temperature and humidity, and we observe strong variation in droplets' evaporation in accordance with their local temperature and humidity microenvironment. We assume that 3% of the initial droplet volume is made of nonvolatile matter. Our analysis confirms that droplets' lifetime is always about one order of magnitude larger compared to previous predictions. Finally, we have been able to produce original virus exposure maps, which can be a useful instrument for health scientists and practitioners to calibrate new guidelines to prevent short-range airborne disease transmission.