The Johns Hopkins Bloomberg School of Public Health turns 100 this year. The school came to life during a time when women frequently died during childbirth and infant mortality was a grave concern. Inadequate nutrition, sanitation and often-fatal diseases were common.

Since then, public-health agencies in the United States and abroad have had numerous victories, such as the eradication of smallpox. In 1916, the average life expectancy at birth in the United States was around 52. Today, it’s nearly 79.

But public health remains a complex and challenging field — figuring out how to control gun violence and addiction, exploring the science of aging, keeping refugees healthy, closing the gap on health-care disparities in minority populations.

And improving public health means navigating the contentious landscape between public good and individual choice. Vaccination provokes controversy to this day.

“Especially in the United States, we have this ideal of rugged individualism,” Michael Klag, dean of the Bloomberg School, said in a phone interview. “But to have a well-functioning society, we need to think beyond the individual and think about what will benefit everyone.”

The issue, of course, is that unless we’re facing an immediate problem (think Zika or the water crisis in Flint, Mich.), most of us just don’t think about it.

“Basically, we are living as long as we do largely because of public health,” said Al Sommer, who preceded Klag as dean. “It’s all these interventions at the population level, like vaccinations and public sanitation.”

Joshua Sharfstein, an associate dean of public health practice and training at the Bloomberg School, alluded to the conflict inherent in intervention. “Sometimes it gets mischaracterized as an attempt to be controlling. But I think the vast majority of people who go into public health do so because they appreciate how illness robs individuals of their freedom and liberty to lead their lives the way they want.”

In celebration of its centennial, the Bloomberg School has drawn up a list of 100 objects that have affected public health, for good and ill.

“We purposefully picked items that seem out of place,” Klag said. “We want people to look at them and think, ‘That can’t possibly have anything to do with public health.’ But they can, and they do.”

The goal of the list is not only to show how far we’ve come but to inspire people to think about where we’re going. “Public health is not a static concept,” Sharfstein said. “It’s not like this happened in the past, and boom, we’re done, we’ve solved it and we can all go home. There’s still a lot of work to do.”

Of the 100 items, which can be found at Global Health Now, we have chosen 10 to highlight. This seemingly odd but fascinating collection is a great way to start thinking outside the box about public health.


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Birth certificates

“Counting births. Counting deaths. It’s how we were able to start looking at the health of large groups of people,” Klag said. Sharfstein added, “You can do something that can shift the whole health of a population and measure whether or not it’s working based on the vital statistics found in birth certificates.” Although birth registries have been maintained throughout the world for centuries, a standardized method of doing so in the United States has been the norm only since the 1930s.


Ralph Nader made a name as a consumer advocate in the l960's with his seminal book, “Unsafe at any speed,” which chronicled the dangers of cars like this red Chevrolet Covair. (Bradley E. Clift for The Washington Post)
The Corvair

In a television ad for the 1960 Corvair, trumpets blare while a stentorian voice commands, “Watch! How it goes!” Viewers are meant to be awed as the car makes short work of standing water and climbs a hill with ease. Despite the ad’s assurance that “nine years of planning and testing” went into the Corvair, the car was fingered by consumer advocate Ralph Nader for its many safety flaws. This, and Nader’s complaints about automobile safety generally, helped spur the creation of the National Highway Safety Bureau, which became the National Highway Traffic Safety Administration.


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Window screens

While we may look at them primarily as air conduits rather than disease-vector barriers, “window screens are certainly not an abstract public-health construct to the people within the Zika box in Miami,” Sharfstein said. Before screens, the only way to effectively keep flies and mosquitoes from entering a house was to shut the windows. This was a rather unattractive option during sultry summer days before air conditioning. While people sometimes used cheesecloth to keep bugs out, what was first called “wire cloth” became the most popular and effective solution. According to the Smithsonian Institution’s National Museum of American History, they were first described as a tool in the fight against disease-carrying insects at the beginning of the 20th century.


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Sidewalks

It’s well documented that walking is a great way to fight obesity and that well-planned sidewalks promote walking. In neighborhoods where there are no sidewalks or where sidewalks are near busy roads, walking can be dangerous. In addition, research has shown that where sidewalks are built — and where they lead — can make them more appealing and better used.


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The desk chair

As a society, we have become increasingly sedentary. In addition to the great amount of time that Americans spend sitting in cars or engaged in leisure activities like watching television, many spend vast stretches of time sitting at work or in school. Studies have found that being sedentary in this manner is associated with cardiovascular disease and diabetes, and for children in particular, an increase in physical activity may help with the learning process.


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American cheese

Processed foods have been around for thousands of years. Bread, beer and pickles are all examples of foods that have been processed by human beings. Processing can keep food fresh longer and can make food safer by killing harmful bacteria. These days, however, products that considered ultra-processed, including American cheese, have begun to make up a significant part of the American diet. “Almost all ultra-processed foods contain sugar and salt,” Sommer said. “And our bodies go bonkers for that,” he said. The availability of such foods has contributed significantly to obesity and obesity-related diseases, particularly in poorer parts of the country.


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Bottled water

Hundreds of millions of people in the world do not have access to safe drinking water. In these places, bottled water is a lifesaver. However, notwithstanding places like Flint, Mich., the tap water quality in the United States is generally excellent, and readily available.

Despite this, many Americans believe that bottled water is safer to drink than tap. And the ads are slick. “People easily consume simple marketing messages — the urban myths,” Kay Dickersin, a professor of epidemiology at the Bloomberg School, said. “It’s our job, and a difficult one at that, to get them the correct information.” In addition to the environmental impact of producing bottled water, the product is not always safe. Several outbreaks of gastrointestinal illness have been traced to bottled water sources.


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The smartphone

Wireless technologies have changed how people live. “It’s amazing,” Sommer said. “You can be in a place where people have no running water, but they have a smartphone. You have to understand that there are places where landlines just aren’t possible — either there is no infrastructure for that, or the infrastructure gets removed by people tearing up the wires and stealing the copper inside to sell.”

“Technology like this is a very creative way to enhance the health of populations or assess the health of populations,” Sharfstein said. It’s not all good news, though: Internet addiction appears to be a growing problem, particularly for kids.


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Vitamin D milk

Deficiencies in vitamins and minerals can cause horrible diseases. Over the past century, fortifying foods has been an effective way of getting essential micronutrients to people.

A lack of vitamin D in children causes, among other things, rickets, a disease characterized by skeletal deformation. Although seldom seen in developed countries today, rickets remained a concern in the United States until early in the 20th century. So beginning in the 1930s, vitamin D was added to foods, most notably milk, a beverage that most young people drink.

“Food fortification is an easy way to get people these micronutrients,” Sommer said. “We all need to eat, but it’s much more difficult to remember to take supplements.”


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The toilet

It’s hard to think of a more important invention for promoting public health. Toilets channel human waste into sewer systems instead of into the water supply. Water contaminated with feces can carry potentially fatal diseases including cholera, dysentery and diarrhea.

According to the Centers for Disease Control and Prevention, diarrhea is the world’s second-leading cause of death in children younger than 5. The World Health Organization reports that, as of 2015, nearly 2 billion people worldwide used drinking water sources contaminated by fecal matter. Public-health advocacy groups such as the World Toilet Organization are working to raise awareness and improve sanitation throughout the world: The annual UN World Toilet Day is Nov. 19.