Sneezing, and Disinfection by Hypochlorites

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Abstract
The authors describe a quantitative study of the number of bacteria-carrying particles given out during sneezing, of their rate of disappearance from the air in a closed room, and of the rate at which they are killed by a hand spray, using a 1% Na hypochlorite soln. For the expt., a small, well-closed room was used. Constant circulation of air of an average temp. and humidity was maintained by means of an electric fan. Samples of air were withdrawn by suction via glass tubes leading from points in the room through one of the walls to a corridor. Open Petri dishes placed 5 ft. from the sneezer were also used. The subject sneezed 4 times in succession[long dash]snuff or a bromine compound was used to stimulate sneezing. Control samples were taken for 5 min. before the sneezing and samples were also taken after spraying the room with the Na hypochlorite soln. Colony counts were then made and the results analyzed. The peak is reached 1 min. after the sneezing at which time 492 colonies per cubic ft. were counted. The count gradually falls so that at 5 min. after sneezing it is 342; 10 min., 288; 15 min., 157; 20 min., 89; and after 45 min. still 4 times the control count are present. After using the spray the counts rapidly decreased and within 10 min. reached the control count. Thus it is concluded that droplet infection is of great importance since 20% of the particles remain suspended for 15 min. and 4% for 30 min. It thus seems probable that the danger of infection from a sneeze may last at least 1/2 hr. in a closed room. The authors finally emphasize the large numbers of infective particles which are emitted in sneezing, and the surprisingly long time before the number suspended becomes negligible.