[R]efrigerators are not only appliances: they are also a key component in the public health system. By sealing food into a clean, cold box and constantly filtering the air inside, refrigerators defend families against the legions of bacteria, viruses, molds, insects, fungi, and parasites that otherwise would contaminate their suppers. Suddenly living without refrigerators, Katrina’s victims couldn’t keep their food safe. Emergency rooms filled with food poisoning victims. People in New Orleans were learning the hard way that they could not take for granted one of the pillars of modern life: public health.

…

Public health is generally pictured in terms of doctors and medical researchers setting guidelines for disease prevention and treatment — the kind of actions associated with the Centers for Disease Control and Prevention and the Food and Drug Administration. But that’s not how the originators of public health thought of it. Nor does that image adequately describe what they set up — the arrangement we live with now. Built up for more than a century, today’s public health system is a massive, interlocking set of laws, standards, institutions, and technologies that undergirds much of our daily lives.

…

The public health system had many beginnings, but among the most important was tuberculosis. […]

In 1882, the German microbiologist Robert Koch discovered its cause: Mycobacterium tuberculosis, a group of closely related bacteria. […] Galvanized by this discovery, volunteers created hundreds of anti-tuberculosis associations across the United States that sought to stop M. tuberculosis from spreading — and launched, along the way, today’s public health system.

Some of the reformers’ ideas were off-base, such as their campaigns to abolish floor-length dresses (thought to pick up deadly bacteria from the ground) and beards (seen as bacterial time-bombs on men’s faces). Others are now so widely accepted that it is hard to believe that anyone had to advocate them. Among these are the notions that people should cover their mouths when they sneeze, wash their hands after visiting the toilet, and not spit on the floor or sidewalk.

All the while, the TB associations were establishing a novel infrastructure of health: hundreds of new TB dispensaries, TB open-air tent camps, and TB sanatoria (specialized hospitals for long-term care). The dispensaries were information centers where technicians diagnosed TB cases and shunted patients to camps (if the case was mild) or sanatoria (if it was severe). The camps and sanatoria served two main functions. The first was a kind of quarantine. By packing TB sufferers into dedicated facilities, the reformers prevented them from infecting others. The second was to provide rest, sunshine, fresh air, and a balanced diet: improved living conditions that would, activists hoped, let TB patients get better by themselves. Mostly, these treatments had little impact. The first real cure for M. tuberculosis was an antibiotic, streptomycin, proven effective against tuberculosis in 1944. But the camps and sanatoria represented the first systematic, nationwide effort to provide a clean environment to improve health.

Coupled with these measures was a raft of new laws and regulations. In the early twentieth century, for example, many urbanites got water from municipal water pumps, drinking from metal cups that hung by the pump handle. Similarly, conductors carried buckets of water on trains, offering drinks to passengers from a common cup. Reformers denounced the cups as vehicles for transmitting M. tuberculosis, and by 1912 they had convinced 24 states to ban them at drinking fountains and the federal government to restrict them on interstate railways. In addition, they had managed to pass 150 urban anti-spitting laws, though apparently these were lightly enforced.

The anti-TB effort set the template for other, later medical campaigns, such as those against hookworm (a parasite that then infected more than a third of the people in the southeast) and typhoid (a disease caused by a lethal variant of salmonella that at the time was rampant in American cities). More importantly, the effort was a launchpad for what became a broader movement to improve Americans’ physical and mental well-being.

…

In practice, the public health system is an overwhelming pile-up of rules and procedures that affect everything from the packaging of milk to the contour of highway curves, from the standards for electric plugs to the performance of automobile bumpers, from noise limits in factories to air conditioning norms in offices, from apartment fire safety requirements to water testing guidelines for sewage plants. Local statutes regulating the design of sidewalks to protect pedestrians from cars, state vaccination mandates to protect children from disease, nationwide environmental laws to protect citizens from dirty air and water: the public health system encompasses them all. It sets down how chlorine must be administered to swimming pools and fluoride to drinking water. How children’s playgrounds in many states must have a foot of impact-absorbing material (wood chips, safety-tested rubber) around each piece of equipment. How construction workers must don protective equipment like respirators, hardhats, and safety glasses. How coaches, pharmacists, electricians, park rangers, and veterinary technicians must be trained in cardiopulmonary resuscitation (CPR), a technique for restarting a person’s heartbeat after it has stopped. And so on. And so on.

The immense network of health regulations is administered by an equally large network of state, local, and federal agencies. The Occupational Safety and Health Administration, the Health Resources and Services Administration, the Federal Occupational Health, the Administration on Aging, the National Highway Traffic Safety Administration, the Food and Drug Administration, the Centers for Disease Control and Prevention, the Environmental Protection Agency, the National Institutes of Health, the fifty state and thousands of municipal health departments — a full list would take many pages.