John Snow (1813 – 1858) breaks the pump handle — During the cholera epidemics of the late 1840s and early 1850s, physician John Snow realized that cholera is transmitted through contaminated water. He was popularly known at the time as the doctor who “broke” the Broad street pump handle because he was tired of waiting for reform. In fact, he convinced the local board of health to shut the pump down after presenting his evidence, and the high profile incident added to calls for sanitary reform from England’s emerging progressive movement.

Alice Hamilton (1869 – 1970) — The founder of occupational medicine in the U.S. and the first woman on the faculty of Harvard Medical School, Hamilton took a leading role in two major environmental controversies of the 1920s involving leaded gasoline and radium dial painters (known as the “radium girls”).

John Muir (1838 – 1913) — America’s most influential conservationist, Muir published 300 articles and 10 major books that recounted his travels and explained his naturalist philosophy. In 1892, Muir and friends established the Sierra Club to, as he said, “do something for wildness and make the mountains glad.”

George Washington Carver (1865 – 1943) researched industrial applications from farm products — a concept that was called “chemurgy” and adopted by conservative agrarians in the late 1920s. Carver is significant in the environmental context because the idea of creating renewable and industrial scale resources from agricultural products was just emerging at a time when the oil, chemical and automotive industries said such systems did not exist or could not work. His ideas, and those of fellow scientists, pointed the way towards the development of biologically compatible paths to sustainable development.

Ken Saro-Wiwa (1941 – 1995) — The popular Nigerian author and journalist was executed in 1995 following a mock trial by the Nigerian dictatorship in response to a human rights and environmental campaign. Shell Oil company had a role in both the execution and the environmental damage in the Ogoni homeland, at the mouth of the Niger River. What angered Sawo-Wiwa and others is that the oil industry was able to lift billions of barrels of oil out of Nigeria and yet completely avoid responsibility for environmental cleanup when devastating oil spills, gas flares, pipeline explosions and chemical dumping ruined the land and made simple agriculture impossible for the Ogoni people. His last words were: “Lord, take my soul, but the struggle continues.”