The Air We Breathe 



261 



these radiations are available from quartz mercury vapor lamps or 

 from carbon arcs. 



Ultra-violet lamps enjoy a wide use in biological supply houses 

 and in hospital nurseries as a means of reducing microbial popula- 

 tions. Some hospitals have these lamps installed in their operating 



Fig. 45. Suspended above the operating table are four ultra-violet 

 Sterilamps which emit ultra-violet light in the bactericidal range and kill 

 air-borne bacteria. {Courtesy of the Westinghoiise Electric Corporation, 

 Pittsburgh, Penna.) 



rooms to minimize post-operative infections. An unusual use of 

 ultra-violet radiation has been attempted in certain banks where 

 these light waves form a "protective shield" for tellers who daily 

 deal with hundreds of individuals at a relatively close range. 

 Unless the exposure is prolonged, however, microorganisms may 

 survive direct contact with these wavelengths of light. The value 

 of this practice in banks is highly questionable. 



