a r l i e r work by t h r e e different i n v e s t i g a t o r s suggests that a biologically active r a d i c a l is f o r m e d when s m a l l a i r ions r e a c t with w a t e r . E x p e r i m e n t s u n d e r t a k e n to d e t e r m i n e w h e t h e r the hypothetical r a d i c a l p a r t i c i p a t e s in the lethal action of negative a i r ions on M. pyogenes a u r e u s r e v e a l e d no evidence of such an effect. Evidently, lethality r e q u i r e s d i r e c t contact of a i r ions with m i c r o o r g a n i s m s .