Imagine yourself as a character in 1830’s Dickensian London. The Industrial Revolution is in full swing, and the city is smothered in coal smoke and soot; the river Thames appears as a gash of sludge spreading miasmatic fumes through the city. If you are a common citizen of the city, your lifespan is, at best, unpredictable. At this point, the Thames is mostly sewage, and the slow-moving river is a cesspit of bacteria and disease. Cholera, a relatively new illness, is the most prolific and has spread like wildfire, claiming lives indiscriminately as it blazes a path of death through the poorest neighborhoods of the city.
By 1866, London had experienced 4 major cholera outbreaks, along with outbreaks of typhoid fever and influenza. The disease was first “found” in London in 1831; I use quotations here because the leading theories of the day did not know cholera was a water-borne disease as we know it to be today, and it had before been a disease found only in the East. A scientific school called the Miasma Theory was dominant, where people believed disease to be caused by bad smells in the air. This had been the dominant school since the Black Plague, and no one questioned it. Cholera was only the latest in a long line of diseases caused by this “miasma”.
In 1842, a man by the name of Edwin Chadwick connected the dots between cholera and living conditions. He was one of the first people to realize that cholera deaths were highest in areas where people lived in their own filth. As a social reformer, Chadwick published his notes, and was appointed to the Board of Health for the city of London in 1848 as the very first sanitary commissioner. While Chadwick believed correctly that cleanliness and separation of waste from people would stem the outbreaks, he too thought the bad smells from human waste were responsible for the disease.
While the miasma theory was the dominant theory of the day, some scientists did believe other origins for disease, and germ theory as we know it today was slowly being formulated across Europe. It was a slow process: miasma had been the most popular theory for centuries at this point. It wasn't until 1854 that Vibrio cholerae, the cholera bacteria, was isolated. Even then, germ theory did not gain real traction until decades later. 1854 also marked the fourth and final cholera outbreak in London. Centered in Soho, specifically Broad Street, it killed over 600 people in the span of about a year. Scientist John Snow noticed the correlation between the location and the spread of disease, creating the map below to map his process, and published these notes with collected data of cases surrounding one particular water pump, the one on Broad Street.
John Snow had previously written a paper in which he challenged the miasma theory, saying that cholera was not caused by bad smells but rather infectious agents in the water. This paper was largely ignored, until he published his addendum with solid statistical and geographical data tracking the disease. While the worst had already passed, John Snow famously and single-handedly ended this outbreak by simply having the handle on the Broad Street pump removed by Dr. Edwin Lankester. Unfortunately, the head of the Board of Health at the time, William Farr, refused to accept Snow’s germ theory over miasma theory. He understood the correlation, and allowed the deactivation of the pump, but introduced no other changes to the London water and sewer systems.
In 1866, London experienced its final outbreak of cholera, where Farr himself collected data showing the epicenter of disease around the Old Ford Reservoir. Germ theory was well on its way to acceptance after Farr’s paper was considered conclusive, and Dr. Lankester was appointed the first Medical Officer for Health in the area of the 1866 outbreak. After the acceptance of germ theory, the worldwide cholera pandemic drew to a close. While epidemics in India and other parts of the world still existed, those in Europe specifically were never as bad as they were before, and epidemiology was changed forever. John Snow saved millions of people’s lives with his discovery of cholera as a water-borne illness. His work has earned him the title “Father of Sanitation Engineering”, among others, and he spearheaded the creation of the Sanitary City across the world.
After his research, Snow was never appointed to any positions within the British health system, but his work has not been forgotten. As an environmental engineer, Snow’s work is seminal. When I consider the classes I take and the work I do as an environmental engineer, so much of it revolves around the work that John Snow contributed to science. In my environmental engineering principles class, for example, we learned about the creation of the Sanitary City. London was considered one of the first sanitary cities, and actions like narrowing the Thames, creating wastewater treatment plants, and reforming sewer construction helped speed this process up. None of this would have happened without the help of Snow and his work pinpointing cholera as a waterborne illness.
In a place like London, the fact that water purification is possible is sufficient; the Thames has more than enough water for the city. However, in a city like Los Angeles with no natural sources of water, we need to take John Snow’s research one step further. Wastewater reuse is a burgeoning field within environmental engineering, and so important at this point in time where we find ourselves struggling with freshwater supply. Desalination could be a great way to recover water, but it only returns about 50% fresh, potable water; the rest is a toxic and concentrated brine which is just disposed of. Wastewater reuse creates a brine as well, but the yield is much higher and creates a circular waste system where freshwater is available as long as humans create waste. I am fortunate enough to be able to contribute to this science in my lab: I create catalysts that convert carcinogens in treated wastewater. Sanitation science is about 30-40% of what environmental engineers study, and this whole field rests on the strong foundation of John Snow’s groundbreaking research and findings. His work not only revolutionized the way cities are planned and how disease is studied, but also helped create a field of work which only grows as our relationship with the environment worsens.