The equipments such as vacuum cleaner and air conditioner may produce much stir in the air of the dispensing room, giving effect to the number of airborne bacteria. The number of falling bacteria was determined in the periods in and out of operation of the machines. Following results were obtained:
1) The operation of an air conditioner caused a decrease in the number of falling bacteria onto the dispensing table, to 1/2-1/4 in the hours from 11: 30 to 13: 30 when pharmacists' working volume gets maximum. 2) Vacuum cleaner was more effective in decreasing the number of falling bacteria, to 1/3-1/5 in the same hours. The effect increased in the concurrent use of both equipments. The bacterial number generally increase in parallel with the working volume and the movement of personnel in the room. But these equipments, operated at the same time, prevented the increase. 3) of the total number of the falling Of bacteria, 75-80% were gram-positive cocci, nearly all of which were staphylococci and micrococci. In contrast, gram-positive bacilli composed only 9-10%. Gram-negative cocci and bacilli accounted for only 1-2%, major species being Neisseria in the former and Enterobacter in the latter.