Harold George Daniel Breidahl was born in Melbourne, the son of an industrial chemist and distiller, and grandson of Daniel Breidahl, Knight of Dannebrog. He studied at Scotch College and Melbourne University, graduating MSc in 1916 with final honours in physiology and MB BS in 1918. Following a term as RMO at Royal Melbourne Hospital he joined the AIF and on demobilisation proceeded with his young wife to Stawell to work in general practice. Tragedy unfortunately befell him there with the death of his wife from a post partem haemorrhage immediately after the birth of their third child Peter. Stricken with grief and remorse, he moved with his three infant children to Western Australia and after a short period in Geraldton began general practice in West Perth in 1929.

Before long he had an enormous clientele of general patients, and in addition he commenced specialising in his major interest, allergic disease. Dr Breidahl was a Master of Science in biochemistry and physiology and as soon as he started work in Perth he offered his services to Perth Public Hospital in the biochemistry department which had recently been established, with Miss D Anderson BSc as biochemist. His son Peter has memories of his going into Royal Perth Hospital at 5 am most days to do one or two hours work in the laboratory prior to the commencement of his own duties in his practice. I am grateful to Dr DH Curnow PhD for his reference to him in his history of the Biochemistry Department:

'A major step was taken by the hospital in 1931 when Dr Breidahl was appointed Honorary Biochemist, a post he held until 1947. It would be appropriate here to record the very great influence that Dr Breidahl had on the department in establishing it as a scientific department in the hospital, with emphasis on scientific method and control of accuracy. He was also responsible for introducing during the 1930s advanced biochemical methods: Colorimetric methods for blood cholesterols and phosphateses for example were established as routine in Perth long before they were being done in the larger Eastern States hospital laboratories'

It was in the biochemistry laboratory indeed that I first met Harold Breidahl one afternoon shortly after I commenced as RMO at the hospital, when I went to discuss the biochemistry results of a patient with Nancy Perrins, the senior biochemist. She introduced me to Dr Breidahl, not as the honorary biochemist, but as the honorary allergist and specialist in asthma. I had just experienced the rather miraculous effect of intravenous Aminophylline in the treatment of a large somewhat alcoholic lady in acute status asthmaticus, and in my enthusiasm burst out in praise of this marvellous new drug. Dr Breidahl answered, 'Yes, Elphick, it's a good drug, and so is Adrenaline, but it must be given in sufficient amounts, slowly, a minim a minute, continuing until relief is obtained', advice which was remembered with respect and gratitude on many occasions during my subsequent career as a chest physician. Harold Breidahl will be remembered best in Perth for his contribution to the management of asthma. He was Perth's first, and for a long time only allergist, and even today questioning older patients regarding their previous history, I learn that their early treatment was carried out by Dr Breidahl.

He established his own laboratory, initially in his general practice and later in his consulting rooms in St George's Terrace. His son still remembers picking countless thousands of dandelions and veldt grass blooms from which the pollen was brushed into jars to be processed by his father, as well as collecting dead animals - cats, dogs and even rats - for the supplies of hair. His assistant for many years in his specialist practice related the preparation of innumerable testing and treatment solutions of pollens, grasses, house dust - including samples of patients' own house dust, collected from their vacuum cleaners - sterilised and purified by a complicated system of dialysis, for the investigation and treatment of his patients. For years, on the roof of his consulting rooms, pollen counts and spore counts were a daily routine.

During World War II he served with the rank of major in the Seconf AIF from 1941 to 1943. He gave up general practice in 1946 to become a full-time allergist and consultant physician in asthma and although he retired from consultant practice in 1957, his interest in asthma continued during the remainder of his life. We at Perth Chest Hospital (now Sir Charles Gairdner Hospital) were sincerely grateful to him for his assistance and wise guidance in the management of sick asthmatic patients during the second year of the hospital's life, when tuberculosis was on the wane, and patients with non-tuberculous chest diseases were admitted for investigation and treatment.

Harold Breidahl was a brilliant student, a highly industrious general practitioner, a meticulous laboratory technologist, and a wise unassuming, gentle, kind man. He became a member of The Royal Australasian College of Physicians in 1938 in the first examination set by the newly formed Board of Censors of the College and elected to Fellowship in 1950. He was honorary allergist at Royal Perth Hospital and Princess Margaret Hospital 1933 to 1950 and consultant allergist at Royal Perth Hospital from 1950 until his death. He was an emeritus fellow of the American Academy of Allergy and an honorary fellow of the Australian Association of Allergists, as well as an associate of the Royal Australian Chemical Institute.

Perth is undoubtedly one of the most allergenic cities in the world and Dr Breidahl's meritorious contribution to the management of allergic diseases over the years was enormous. In 1962 he developed malignant hypertension which he diagnosed himself when he noticed the sudden severe loss of vision. Fortunately, following treatment by his young friend Dr William Smith, his vision recovered completely allowing him to continue a favourite extracurricular activity, reading British history.

He monitored his own blood pressure control under the supervision of his physicians, manipulating newer drugs with great interest and with his characteristically meticulous attention to detail and critical discernment. He maintained remarkable fitness and enjoyed running on the beach and surfing almost daily until a few months prior to his sudden quiet death during sleep at the age of 86. He is survived by his daughter and two sons, one a Fellow of the Royal College of Physicians London and RACP, and the other a fellow of the RACP and a senior radiologist.