Polio and Swimming Pools: Historical Connections

June 28, 2012 Project Director

Athena, Oregon, 1941. Russell Lee, photographer. Library of CongressToday's post is by History of Vaccines intern Alexandra Linn.

When the New York Times announced that Franklin Delano Roosevelt was diagnosed with polio on September 16, 1921, fear swept the nation. Polio, a little-understood illness at the time, had suddenly disabled  a wealthy and prominent politician on the cusp of his career, making it clear that any American, irrespective of social status, was potentially susceptible to the disease.  With the national spotlight focused on the issue, the search for a cure or vaccine began, and the defeat of the dreaded illness became an important health objective in America almost overnight.[1]

Polio is an enterovirus that infects the gut, and in certain cases, can travel up to the nervous tissue causing neuron death and ultimately paralysis. After the first U.S. cases were identified in the late 1800s, the numbers grew to a high of nearly 60,000 in 1952. The virus seemed to thrive in the summer months, with a “polio season” peaking in mid- to late-summer, and receding with the cool weather.[2]

FDR’s sudden illness occurred during a trip to a vacation house and lake in New Brunswick, Canada. Fearful parents jumped on this association, and began warning their children against swimming in pools, lakes, or any area with open water. Pools were vacated, lake homes were avoided, and swimming became seen as a dangerous exercise.[3]

How did this scare change swimming pools, and how did their association with polio fade away?

Swimming pools date back to the time of the ancient Greeks and the Roman Empire, when public baths were a comfortable place for socializing and relaxing. The first public swimming pool in the United States was built in Massachusetts in 1887. Baths and public swimming areas became common in large cities by the 1920s, with thousands of pools open throughout the United States.[4]

With the growth in popularity came the need for better sanitation measures. Originally pools used archaic filtration systems that required that water filters, and the actual water itself, to be changed frequently. Chlorine was discovered and produced prior to WWI in the early 1900s, but it was not until the war invigorated its manufacture that its use truly came into vogue. By the time of the polio scare in the late 1930s and 1940s, chlorine was used widely in public swimming pools as a sanitation measure.[5]

Still, this didn’t prevent the panic that arose over the public’s fears that children could be exposed to the poliovirus in community swimming pools.

In 1946, however, a study showed that chlorine was actually one of the few known chemicals that could inactivate the virus.[6] Although polio is resistant to common soaps and chemicals of low pH – which is one of the reasons it was able to spread so efficiently -- it can be rapidly inactivated by chlorine, as well as by heat and formaldehyde. Formaldehyde was the chemical ultimately used to inactivate the virus in Jonas Salk’s inactivated polio vaccine, or IPV. [7]

The problem of polio transmission had not been solved, but swimming pools regained popularity as a fun and exciting summer venue for families. Moreover, chlorine, as a polio disinfectant, became the new face of sanitation, with strict regulations on chlorine in pools in place by the early 1960s. [8]

So the next time you hear someone complaining of the smell of chlorine, or even the fact that it might turn some people’s hair a greenish hue, tell them about the role of chlorine in the public health crisis that panicked the United States in the mid-1900s and emptied community pools.


[1] David M Oshinsky, Polio: An American Story (New York: Oxford University Press, 2005), 24.

[2] Kevin Olsen, "Clear Waters and A Green Gas: A History of Chlorine as a Swimming Pool Sanitizer in the United States," Bulletin of the History of Chemistry 32, no. 2 (2007): 135, http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/v32-2/v32-2%20p129-140.pdf.

[3] Olsen 135.

[4] Olsen 129-130.

[5] Olsen 130-1.

[6] Olsen 135.

[8] W. Sullivan, “Swimming Pools Get Health Code,” New York Times, November 16, 1961, 41.


Posted by John (not verified)

I contracted polio around 1950 from an outdoor swimming pool in the uk.althoug almost paralised down my left side with electric shock treatment and quick action in hospital I was almost cured,however 25 years later I had to have lotwer part of left llung removed,since them I have infections.

My question is how could the polio get into the pool and althou Many years ago was the pool owner(counsel) liable.

Thank you


Posted by Karie Youngdahl

Hello, John,
I'm sorry to hear about your experiences. Poliovirus is spread via the fecal-oral route, so the water could have been contaminated by anyone who entered the pool who was infected with the virus and wasn't practicing adequate toileting hygiene. As far as liability is concerned, I'm not sure how that would have been handled in the 1950s, especially if the operator was using what were then considered to be normal pool maintenance practices.
Karie Youngdahl

Posted by Anonymous (not verified)

John, could it be possible that you suffer from long term damage of DDT exposure?

Posted by Jack Heginbotham (not verified)

You forgot to mention that 80-95%(depending on the information source) of people infected with Polio, never knew they were infected because their inherent, unvaccinated Human Immune System defeated the disease before it became symptomatic. From what I have read, only 1-3% of those infected developed the devastating neurological damage that terrified parents.

The swimming pools & shady swimming holes were the problem. Depending on the popularity of the pool or pond, hundreds to thousands of swimmers & their family members could be infected at any given time in a community. When all the public pools started using an EFFECTIVE level of chlorine, the epidemics ended overnight. The Vaccine Industry took credit for ending Polio but it is now obvious that the polio vaccine had nothing to do with stopping the polio epidemics. However, 98 million people vaccinated with the vaccine were dosed with the Simian Virus 40 (SM40). https://www.ncbi.nlm.nih.gov/pubmed/10472327