Fig. 43. (A) An unstifled sneeze with clouds of bacteria-laden 

 droplets being expelled. (B) A sneeze stifled with the bare hand. Some 

 droplets get past the hand into the air. (C) A sneeze stifled with a 

 handkerchief. Still fewer droplets are expelled into the air. {Cour- 

 tesy of M. W. Jetmison, S.A.B. Nos. 5, 9, 10.) 



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