In the spring of 2003, 329 people contracted an infectious disease in a high rise building in Hong Kong. 42 of those 329 people lost their lives.
The building — Amoy Gardens — was the epicenter of the 2003 outbreak of SARS. Almost one-fifth of all recorded SARS cases and deaths in Hong Kong emanated from Amoy Gardens.
And as we reckon with a strain of coronavirus (SARS-CoV-2) very similar to the one that killed 42 Amoy Gardens residents in 2003, we can look to history to guide the future of pandemic responses in dense urban areas like Hong Kong.
Where Poor Plumbing Can Go Wrong
We often take for granted the creature comforts that make our lives smoother. We assume the lights will go on when we flip the switch. We assume the oven will heat up when we turn the knob. We assume the smoke detector will sound in the event of a fire.
Perhaps more than any other critical aspect of modern life, we take for granted the plumbing that conveys all sorts of fluids around our residences, buildings, and cities.
The etymology of the word plumbing stems from the material used to build pipes in the Roman Empire. Plumbing derives from the Latin word for lead: plumbum. As we now know, lead is an extremely dangerous substance that often causes serious health problems in the human body. It’s a reminder that when plumbing is done wrong, things can go very wrong.
Before the Industrial Revolution, poor plumbing wasn’t as problematic since cities weren’t as crowded as they are now. But as industrialization encouraged dense overcrowding in unprepared cities, places like New York and London endured frequent spread of illnesses like smallpox and typhoid fever. Hong Kong learned firsthand the downsides of poor plumbing in 2003.
Respiratory viruses like SARS usually spread through direct person-to-person contact. But these viruses spread through other means too. In tall buildings like Amoy Gardens, defective plumbing can allow virus transmission without direct contact. Faulty pipes can give virus particles — often called aerosols — the breathing room they need to spread.
The potential for coronavirus transmission through plumbing has been scientifically verified. Four co-researchers published the results of an experiment in 2017 from an experiment on a full-scale two-story wastewater plumbing test rig. Aerosolized pathogens were found in the air on both floors, and the droplets even contaminated surfaces both in the rooms and in the plumbing system itself.
How Poor Plumbing Can Cause Disease Outbreaks:
How can this happen? Typically, pipes have a U-shaped water-filled trap (often called a U-bend or U-trap) that prevents fluids and odors from coming back up. But leaks and other plumbing defects can keep the pipes too open, allowing contaminated air to recirculate freely and expose residents.
This risk is heightened during an event like a pandemic, which confines people in their residences and overloads hospitals with sick patients. This redistribution of human activity can strain those U-bends from overuse, potentially leading to blown water seals that enable recirculation of contaminants. Incidentally, plumbing underuse from that same redistribution of human activity can also cause evaporation of the water in U-bends, making them ineffective.
Blown water seals caused the Amoy Gardens outbreak in 2003, according to a World Health Organization investigation. The WHO found that when residents had diarrhea in the building’s toilets, airborne virus-laden particles could spread from one apartment to another.
“When the bathroom was in use, with the door closed and the exhaust fan switched on, there could be negative pressure to extract contaminated droplets into the bathroom,” Yeoh Eng-kiong, Hong Kong’s secretary for health, welfare and food, said at the time, according to the Washington Post. “Contaminated droplets could then have been deposited on various surfaces such as floor mats, towels, toiletries and other bathroom equipment.”
In a vacant apartment in a separate high rise not too far from Hong Kong, this happened again in the initial stages of the COVID-19 pandemic. An in a heavily occupied apartment building in Hong Kong, it likely happened too. A 62-year-old woman became the second person in the building to catch COVID-19; the first person lived 10 floors above her, raising the question of how the coronavirus could spread without direct face-to-face contact.
The probable culprit? Plumbing.
The Next COVID Is A When, Not An If
The question of whether or not a pandemic will strike again is not an ‘if’. It’s a ‘when’. In an August 2020 report published in the journal Cell, Dr. Anthony Fauci and epidemiologist David Morens — longtime colleagues at the National Institute of Allergy and Infectious Diseases (NIAID) — foretold the beginning of “a pandemic era” for humanity driven largely by deforestation, urban crowding, and wet markets for wild game.
Fauci and Morens thus consider environmental degradation “the key determinant of disease emergence” in the 21st century. The two infectious disease experts recommend using the COVID-19 pandemic as a guide to future pandemic responses.
Experts told BuzzFeed this is a golden opportunity to rethink the current approach of treating each pandemic — H1N1 in 2009, Ebola in 2014, and COVID-19 among many recent examples — as a one-off emergency and instead view pandemics as a continuous public health threat worthy of preventative treatment. In this vein, cities should view COVID as both a wake-up call to remain vigilant and an opportunity to learn lessons for the future.
Perhaps the best policy choice cities can make is to create separation between urban spaces and wild spaces. This may seem counterintuitive; isn’t it wrong to disassociate human activities from natural ones and intentionally separate humans from the natural world?
In general, that’s true. But 75% of the world’s newly emerging infectious diseases are zoonotic, meaning they spread from animals to humans. Thus, cities should aim to cultivate natural green spaces (empowering city dwellers to reconnect with nature, as I wrote back in June) while maintaining boundaries with truly wild habitats, where potential vectors of diseases lurk in the bodies of creatures with minimal exposure to humans.
Curbing the disease-spreading potential of wet markets and deforested areas is one thing. Nevertheless, that’s only a first line of defense. In densely populated cities, proper planning and design must incorporate the serious potential for future disease spread and devise urban environments better equipped to handle whatever nature can throw our way.
And in crowded high rise buildings like Amoy Gardens, that effort starts with the hidden infrastructure we often take for granted, like plumbing.
The Simple And Cost-Effective Solution For Poor Plumbing
The solution for the faulty water seals implicated in Amoy Gardens is both simple and cost-effective. Approved and certified Sanitary Water Valves should replace U-bends in both new and existing construction.
These valves, which are both dry and airtight (unlike their U-shaped counterparts), prevent pressure fluctuations that can give aerosols the breathing room they need to spread. The waterless traps greatly improve the effectiveness of plumbing systems. But they can be used for other purposes like boilers and air conditioning systems.
Nonetheless, as with other areas where better infrastructure can save lives, both time and money is required to keep people safe. But now that the entire world has experienced the devastating impacts of a worldwide pandemic unleashed by poor infrastructure and design, what price will people be willing to pay to stay safe and healthy going forward?
One critical takeaway from the Amoy Gardens outbreak: if cultivated haphazardly, human connection can be a double-edged sword. The biggest draw of dense urban areas like Hong Kong is their vitality and energy, which stems from the conglomeration of different kinds of people.
But as cities get denser, cities must walk the thin tightrope between bringing people closer together and keeping them safe.
Faulty sewage is just one example of where city life can go wrong. But with smarter design, that doesn’t have to happen — and it shouldn’t.