[Canaries, germs, and poison gas. The physiologist J.S. Haldane's contributions to public health and hygiene].

The Scottish physiologist John Scott Haldane (1860-1936) spent most of his professional career in Oxford after graduating from the medical school in Edinburgh. He was deeply involved in applying basic science on problems in society but also making these problems guide his choice of projects in his experimental work. Thus, he has demonstrated that the increased contents of carbon dioxide in dwellings, schools, and factories was of less importance than the high contents of bacteria and fungal spores, and that even the foul air in the sewers was less harmful than that in crowded dwellings. He demonstrated that most miners did not die of lack of oxygen or trauma after colliery accidents but of carbon monoxide poisoning. The miners had relied on the ability of their candle or lamp to burn, but this would not be influenced by the presence of carbon monoxide. Thus, he introduced the canaries, which due to their small size and correspondingly relatively higher metabolism would faint about 20 minutes prior to humans. Haldane was called to investigate the ventilation and quality of the air in Cornish tin mines, since the miners suffered from fatigue or even fainted. The air and ventilation was sufficient, but the miners suffered from anaemia due to ankylostomiasis. After improving the hygienic conditions in the mines this became a minor problem although not completely eradicated. During World War I, Haldane became involved in protection of the allied soldiers when the German troops started using poison gas. In all cases he made rather drastic experiments on himself, his coworkers and even his son by exposing them to low oxygen, high carbon dioxide, carbon monoxide, or chlorine. He improved the gasmasks and introduced oxygen as a therapeutic agent. His big scientific mistake was that he insisted on the presence of an active oxygen secretion in the alveoli in order to explain the increased oxygen uptake during work and as part of acclimatisation to high altitude. workers and even his son by exposing them to low oxygen, high carbon dioxide, carbon monoxide, or chlorine. He improved the gasmasks and introduced oxygen as a therapeutic agents. His big scientific mistake was that he insisted on the presence of an active oxygen secretion in the alveoli in order to explain the increased oxygen uptake during work and as part of acclimatisation to high altitude.