628 ANNUAL. REPORT SMITHSONIAN INSTITUTION, 1911. 



In pneumonia we see the same thing; the patient is forced by the 

 feeling of illness to keep quiet in bed. How this adjustment is 

 brought about is a subject for further research. It will be of especial 

 interest to see the effect of ozone on the oxygen partial pressure of the 

 blood. We would draw attention to the fact that high pressures of 

 oxygen produce inflammation of the lung (Lorrain Smith, L. Hill, 

 and J. J. R. 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 deodorizer. It masks rather than destroys 

 smells. Its practical value in relieving the nervous system from the 

 depressant influence of an unpleasant odor is none the less for tins. 



(2) A concentration as little as 1 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 discomfort 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 winch will not irritate the respirator} 7 " tract. 



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

 trations even less than 1 part per million. There is no conclusive 

 evidence of a prehminary 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 smell. 



(6) Ozone in somewhat higher concentrations (1 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 immunizing 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 research fund. 



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

 10 minutes to 2 parts in 10 millions of ozone may lower the rectal 

 temperature of rats as much as 3°, while control rats maintained 

 their normal temperature of 38.5° C] 



