Utilization of Ultraviolet Germicidal Lamp for the Purpose of Public Health

Study Concerning the Effectiveness of Ultraviolet Germicidal Lamp for the Purification of air in the room (I)

Abstract

An ultraviolet germicidal lamp was installed in an air-tight room and with the layout ofvarious. conditions a fundamental observation was made. In the preparatory experiment, falling bacteria in the air-tight room are exhibiting some variations under a variety of slight conditions and the greatest one is by the presence of human beings. The mere occupation of human beings showed a tendency toward a considerable increase in the number of falling bacteria. In particular, movement of humans further strengthened this tendency. Moreover, it was found that the number of dusts floating in the room is exerting large effects on the vicissitude of falling bacteria. In the instance of instollation of an ultraviolet lamp with the establishment of all sorts of conditions, a rapid decline in the number of falling bacteria (number of colonies) was noted through illumination. Lighting prior to an entrance into the room can restore in 15 minutes the purification of air as it was, although a temporay increase in the number of bacteria was observed through the actof entering the room. A lso, the simultaneous lighting with entrance into the room led to a decrease of the　bacteria in 30 to 60 minutes, there being a purifying action on the air. In the air-tight room ; judging from the germicidal effectiveness on the indoor air alone, a fairly striking effectiveness can be achieved_??_by means of the installation and lighting of an ultraviolet germicidal lamp.