Kinetic Monte Carlo photonic model to simulate the UV inactivation of airborne microorganisms

Ultraviolet irradiation can effectively inactivate airborne microorganisms. In this context, a stochastic model based on photochemical inactivation is here presented to simulate the inactivation of microorganisms transported in both laminar and turbulent flows. The model, inspired from radiological and nuclear disciplines, introduces an inactivation probability, i.e. the probability that a single photon inactivates one microorganism. This model, here referred to as photonic model, is highly compatible with computational fluid dynamics and tracks the trajectory and fate of every airborne microorganism, as it moves through an ultraviolet irradiation field. The model, validated against literature data, is a solid alternative to the classical Eulerian model relying on a susceptibility constant. The model will find application in the design of UV air purifiers and in scenarios where photochemical inactivation takes place. • The probability of microorganism inactivation by a hitting photon is derived. • A Monte Carlo model is developed to simulate UV inactivation of microorganisms. • The Monte Carlo model is coupled to computational fluid dynamics. • The model is validated for different wavelengths, microorganisms and flow regimes.