Fizika aerogenih in kapljičnih okužb

Članek obravnava širjenje okužb, prenosljivih s kapljičnimi izločki, ki nastajajo pri govorjenju, kašljanju, kihanju itd. Glavni namen članka je opredeliti, kaj se s kužnimi kapljicami dogaja, ko zapustijo telo in vstopijo v okoliški zrak. Za analizo obnašanja kapljic je vpeljan poenostavljen model s silo teže, Stokesovo silo in izhlapevanjem kot glavnimi dejavniki na kapljice. Poseben poudarek je namenjen vplivom relativne vlažnosti zraka. Izpeljana sta čas sedimentacije in čas izhlapevanja kapljic v odvisnosti od njihovih velikosti. Slika je nato nadgrajena še za kapljice vodnih raztopin, kjer topljenci preprečujejo popolno izhlapitev kapljice. Na koncu so komentirani še pomembnejši nefizikalni dejavniki, ki vplivajo na širjenje kapljičnih okužb, a so bili izpuščeni iz obravnavanega modela.

The physics of airborne and droplet-transmitted infections

The paper discusses the spread of infections transmittable via droplet secretions generated during speaking, coughing, sneezing, etc. The main purpose of the paper is to define what happens to infectious droplets after leaving the body and entering the surrounding air. A simplified model for the analysis of droplet behaviour is constructed, with the force of gravit, Stokes’ drag and evaporation as the main factors affecting the droplets. A special emphasis is paid to the role of relative humidity of the air. From the model size dependent sedimentation time and evaporation time of droplets are derived. The model is then extended to include droplets of aqueous solutions, where the presence of solutes prevents the complete evaporation of droplets. The discussion is completed with an overview of important nonphysical factors that also affect the spread of droplet-transmitted infections but were left out of the presented model.