This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Dewar and McKendrick pointed out the remarkable fact that, instead of the blood becoming more highly oxygenated under ozone-inhalations, it assumes venous characters in all the vessels, a fact which is explained by the greater density of this gas interfering with the due excretion of carbonic acid from the blood; it causes also some local irritation of the lining of the air-passages, and it induces slowing of the heart-action and respiration ("Proceedings of the Royal Society," 1873-74).
This was not in accord with previous observations, for Dr. Ireland had stated that ozone quickened respiration and circulation, excited the nervous system, and promoted coagulation of blood (Edinburgh Medical Journal, 1862-63, p. 729), but it is probable that his animals respired mainly oxygen. Day also had found that oxygen, "ozonized in proportion of one-twelfth, caused rapid respiration and heart-action, and much local irritation;" but quite recently Dr. John Barlow has confirmed and added to the observations of Dewar and McKendrick. He reports that ozonized air depresses the nervous system, probably through leading to accumulation of carbonic acid in the blood; it lessens the frequency of respiration, and hence also of heart-action, together with the excretion of carbonic acid and the absorption of oxygen. It irritates the pulmonary mucous membrane, and may cause bronchitis or lung-congestion (Red-fern), or even asphyxia. It decolorizes the red corpuscles, and causes a granular appearance, probably from uniting with haemoglobin; it stops the amoeboid movements of the white corpuscles, and renders the nucleus apparent; there is no evidence of its entering the circulation in a free state.
As illustrating its irritant effect, Dr. Barlow records its producing an obstinate inflammation of the nasal membrane (Journal of Anatomy, October, 1879).