1911.] 



The Physiological Influence of Ozone. 



407 



in the body. On inhaling ozonised air ourselves and expiring through the 

 iodine test solution we find no evidence of ozone in the exhaled air. It is 

 all taken up by the wet mucous surface of the respiratory tract and exerts 

 its effect there. 



Table I. — Lethal Dose. January to March, 1910. 



Animals. 



Parts of ozone 

 per million. 



Duration of 

 exposure. 



Result. 



2 rats 



15 



3£ Lours 



Died following night, lung showing pneu- 



2 „ 

 2 „ 

 2 rats, 1 cat 



1 dog, 3 rats 



2 



3—5 



7s 



10—20 



S " 



2 „ 



No ill effects. 



Rats quiet, fur standing up. Recovered. 

 Cat killed next day ; signs of lung irritation. 



Disordered breathing of all animals ; all re- 

 covered. 



Jerky breathing ; soon recovered. 



Dyspnceic ; one had snuffles ; soon recovered. 



Dog's breath disordered ; developed cough 

 and bad breathing 1 hour after. All 

 eventually recovered. 



Depressed. Breathing disordered ; moist 

 sounds ; recovered. 



Fur ruffled ; recovered. 



No permanent ill effects. 



Died ; pneumonic signs found po.it mortem. 



Yery disordered breathing ; eventually re- 

 covered. 



2 goats 

 2 „ 

 1 dog, 3 rats 



2 goats 



2 rats 



1 rat 

 1 mouse 

 1 » 



9£ 

 7 



II* 



10 

 11 

 20 

 40 



34 „ 

 3* „ 

 2t „ 



3 hrs. 5 mins. 

 4 hours 



On breathing two to three parts per million, we ourselves find it 

 irritating to the respiratory tract, with a tendency to produce, in this 

 concentration, headache and oppression. The irritation set up by ozone, 

 together with its strong characteristic smell, affords ample warning, and 

 would prevent anyone exposing .himself unintentionally to a dangerous 

 concentration. The irritation set up would naturally make anyone remove 

 himself from the influence of the ozone before any serious damage to the 

 lungs had been set up. As far as we can see, then, no serious risk can arise 

 from the use of ozone generators, so long as the generators are not placed in 

 a confined space from which escape is impossible. 



It is only possible to estimate concentrations of much less than one part 

 of ozone per million parts of air by passing very large quantities of the 

 ozonised air through the acidified potassium iodide solution. We find 

 concentrations of far less than one in a million parts can be both smelt 

 and tasted : the physiological test for ozone therefore is extraordinarily 

 delicate. If ozone is used in a ventilating system, we think it should be in 

 such concentration as is scarcely perceptible to a keen sense of smell. 



Ozone has most potent action as a deodoriser. We tested this by filling 



