ULTRAVIOLET LIGHT — GERSHENFELD 219 



quarters supplied. Most of this recirculated air before treatment is 

 contaminated with bacteria. The proper installation of ultraviolet 

 radiation in air-conditioning ducts is practiced commercially for the 

 destruction of bacteria. By this method nothing is added to the air 

 nor is anything which is desirable removed. Not only office, apart- 

 ment, and other buildings, but many railroads are now using ultra- 

 violet irradiation in combination with air-conditioning units so as to 

 control better the sanitary quality of the air supplied. This supple- 

 ment perfects air conditioning, for air sanitation joins the physical 

 comforts offered by the latter. We can expect more and more stores, 

 theaters, restaurants, other public places, and private homes to have 

 this new type of installation added to their quarters. 



Manufacturing plants and testing laboratories. — In pharmaceu- 

 tical, chemical, and biological laboratories where in the manufacture 

 of various preparations, especially serums, vaccines, and other sterile 

 medicaments, it is important to obtain a sterile end product for 

 marketable purposes, ultraviolet rays employed during all or many 

 of tlie stages of processing such pre[)arations, by eliminating air 

 borne bacteria, have proved to be a valuable aid in avoiding possible 

 contamination. In the preparation of ointments, cosmetics, and 

 other pharmaceuticals, the keeping qualities of these preparations 

 are reduced and losses result because of spoilage due to the develop- 

 ment of fermentations by yeasts and other bacteria or by growths 

 of molds and fungi. The use of ultraviolet irradiation to maintain 

 bacteria- and mold-free conditions in the air during the processing 

 and at the same time wherever possible to sterilize the surfaces of 

 jars and other containers subject to contamination has resulted in 

 prolonging the life of these preparations. 



In testing laboratories, where all kinds of materials are examined 

 to determine whether they are sterile or to note the bacterial content, 

 it is most important that all precautions be taken to eliminate con- 

 tamination during the period when the materials are removed for 

 the tests to be made and subsequently when examinations are con- 

 ducted. Aseptic conditions throughout are absolutely essential. Air- 

 borne contamination is the dread of all workers who do culturing 

 and conduct other bacteriological examinations. The use of selected 

 ultraviolet radiations is a valuable addition in combating possible con- 

 tamination during such testing. Suitable equipment has been de- 

 signed for a portable ultraviolet unit which can be moved easily at 

 will to any quarter and irradiate effectively areas of definite cubic 

 contents. 



