There have been a few studies about the production of aerosols from the use of oxygen masks. However, although their methodology was quite different, a useful comparison can still be made with the study by Somogyi et al,9 who produced images of exhaled airflows using three different oxygen masks on a human volunteer. Their study is not directly comparable to this one mainly because the oxygen masks they used had no oxygen flow supplied. Only the volunteer’s natural exhalation after brief breath holding produced the air movement. This is not a natural breathing cycle, and, in this respect, the cyclical respiration pattern in the human lung model presented here may be more realistic. Although Somogyi et al9 showed images of the behavior of the exhaled air plume, they did not report quantitative data, such as the distance traveled by the visible air plumes shown in their images. However, a closer inspection of their Figure 1A, which illustrates a side plume of exhaled air emitted from a simple nonrebreathing oxygen mask, appears to show that it extends approximately two head diameters away from the mask. The head diameter of an adult has been reported to be approximately 13 to 16 cm.,15 Thus, the extent of the visible plume shown in their Figure 1A can be estimated to be approximately 0.30 m. Furthermore, these authors stated the following: “The spread of the exhaled gas may be greater than shown, as evaporation and reduction in density of the droplets at the margin of the plume may limit their effectiveness as markers.” Although the methodology and human lung model parameters used in this study may have been somewhat different (oxygen flow, 4 L/min; respiratory rate, 12 breaths/min; tidal volume, 0.5 L), the distance traveled (0.40 m) by the exhaled smoke plume in this study seems remarkably similar.