1911.] 



The Physiological Influence of Ozone. 



415 



effect of ozone on the oxygen partial pressure of the hlood. We would draw 

 attention to the fact that high pressures of oxygen produce inflammation 

 of the lung (Lorrain Smith, L. Hill, and J. J. E. Macleod) similar to that 

 produced by ozone. It is this resemblance which in part led us to make this 

 research. 



Conclusions. 



(1) Ozone is a powerful deodoriser. It masks rather than destroys smells. 

 Its practical value in relieving the nervous system from the depressant 

 influence of an unpleasant odour is none the less for this. 



(2) A concentration as little as one per million is irritating to the 

 respiratory tract. Exposure for two hours to a concentration of 15 to 20 

 per million is not without risk to life. The irritative effect and the dis- 

 comfort produced thereby — cough, headache — give ample warning, and there 

 is no risk from inhaling ozone so long as an outlet for the instinctive escape 

 from its influence is open. It is necessary that systems of ventilation in 

 which ozone is used should be dealt with by those experienced in the 

 matter, so that concentrations may be supplied which will not irritate the 

 respiratory tract. 



(3) The respiratory metabolism is reduced by ozone, in concentrations 

 even less than one part per million. There is no conclusive evidence of a 

 preliminary stimulation of metabolism preceding the fall. 



(4) The beneficial effect of ozone obtained by the ozone ventilating 

 systems is to be explained by its effect on the nervous system. By exciting 

 the olfactory nerves and those of the respiratory tract and skin, it may 

 relieve the monotony of close air, the smell of tube railways, in cold meat 

 stores, hide stores, and other trades. 



(5) There is no harm in breathing weak concentrations of ozone, such as 

 can be scarcely sensed by a keen sense of small. 



(6) Ozone in somewhat higher concentrations (one per million) may have 

 some value as a therapeutic agent if inhaled for brief periods ; by irritating 

 the respiratory tract it may act as a blister or fomentation and bring more 

 blood and tissue lymph to the part. The blood and tissue lymph contain the 

 immunising and curative properties. It seems to us a simple and convenient 

 way of applying a " blister " to the respiratory tract. 



This research has been carried out with the aid of a grant from the London 

 Hospital Eesearch Fund. 



[Note added November 21, 1911. — We have found that exposure for 

 10 minutes to two parts in 10 millions of ozone may lower the rectal 

 temperature of rats as much as three degrees, while control rats maintained 

 their normal temperature of 38-5° O] 



