Response to “Aerosol or droplet: critical definitions in the COVID‐19 era”

We thank our esteemed colleagues from the University of Pennsylvania for their valuable comments. We could not agree more that the use of appropriate semantics is of critical importance in defining the risk of aerosolization during endonasal procedures. The existing literature often conflates the terminology regarding transmission mode (eg, droplet vs airborne) with the description of the associated aerosolized particles (eg, droplets vs droplet nuclei, respectively). As Kohanski et al point out in their letter, airborne particle sizes are commonly described as approximately ≤5 μm. ¹ However, the authors would advise that these strict size cutoffs should be interpreted with caution, as even 20‐μm droplets have been shown to evaporate into smaller droplet nuclei under proper conditions. ² Kohanski et al further expressed concern based on Figure 3A that the reported conditions may have produced larger droplets outside the 100‐μm range. Although this is true, the authors would point out that the title of this figure refers to the “maximum” droplet diameter as a function of distance. The full range of particulate sizes extended from 36 to 413 μm at distances of >42 cm. The upper end of this range is commensurate with the physiologic aerosol sizes reported during coughing, ³ and thus, in the authors’ opinion, this represents a reasonable simulation of an irritative clinic procedure.

We appreciate this opportunity to clarify the data set for the readership and we also take this opportunity to reiterate the point made in the Discussion that the lower limit of detection in this study design was 20 μm. Therefore, this methodology explicitly excludes the ability to reliably detect particles in the airborne range. We anticipate further studies both by our group and others to specifically interrogate this class of aerosols.