John Scott Haldane was a Scottish physiologist and philosopher, born in 1860. He is best known for his pioneering work in the field of respiratory physiology and for developing methods to study the effects of gases on human health. Haldane's research contributed significantly to our understanding of oxygen and carbon dioxide in the bloodstream. Haldane also played a crucial role in the development of gas masks during World War I, improving safety for soldiers in chemical warfare. His work laid the foundation for modern occupational health practices, emphasizing the importance of understanding environmental factors on human physiology.