From Arsenic Poisoning to Vertical Gardening

A Meditation on Walls

Traveling through the Sidi Ifni region of southwestern Morocco you may come across a bizarre sight on the horizon. From the foothills of the mountain, mesh walls rise up like sails woven from a lattice of insect eyes. These curious netted walls are doing something unbelievable; they are harvesting fog. In water-stressed regions like Morocco, Eritrea, and Latin America, scientists have begun collecting atmospheric condensation so that this indispensable resource does not go to waste. These nets trap water vapors––roughly 6,300 liters a day sending them into collection bowls below where they travel to nearby villages. 

These fog harvesting walls illustrate just one of the astounding things walls do for us. 

From Humpty Dumpty to Pink Floyd––walls captivate us. They drive our metaphors, music, and mythology. Walls have defined political regimes, fomented border disputes, and killed countless people while also granting us privacy, protection from the elements, and solutions to pressing environmental crises. Walls have surrounded untold human achievements. They have jailed and guarded revolutionary thinkers, dogged scientists, and separated or hidden passionate lovers.

Mesh fog harvesting wall on the Moroccan Mountainside 

So, from brittle roman bricks to vertical vegetable aquaponics, what can walls tell us about human ingenuity and failure? How did we go from dying of arsenic poisoning to seismically retrofitting our domiciles? 

Dying Walls

A few days ago my landlord sent me a pamphlet from the EPA about the presence of lead-based paint in older homes. Normally, I would not have given this warning much thought. I don’t have much of a penchant for eating paint chips and I am a believer in the German tradition of airing out the abode and ushering in the fresh air. However, I have been thinking more about lead than usual.

In his recent video, Dr. Derek Muller, a science communicator who runs a popular YouTube channel called Veritasium, released an episode about the dangers of lead poisoning. In this video, Muller focuses on the history behind the addition of lead to fuels, a phenomenon partially responsible for the dangerously high concentrations of lead found in contemporary humans. Of course, leaded gasoline is not the only thing responsible. Until relatively recently, lead was present in a miscellany of industrial products from the solder on food containers to the metal nipples on baby bottles.

While most countries have now banned the addition of lead in fuels, the pamphlet reminded me that lead continues to imperil us. Many continue to suffer a slow and innocuous poisoning, responsible for behavioral delinquency, lowered IQs, and two-thirds of unexplained intellectual disabilities in the US. Walls in particular, or perhaps more accurately the lead-based paint we slather on them, have posed a health risk for some time.

When brightly painted interiors took off in the baroque era, many noxious additives were added to make the paint more vivid, luxurious, and glossy. Aside from lead, chemicals such as arsenic and cinnabar added luster and depth to paint. While visually striking, colors like Scheele’s Green and Cadmium Red contained toxic chemicals that lingered in the dank, damp houses, contaminating the air inside the home and poisoning the inhabitants. Many believe that Napoleon, the World Spirit on horseback, died from a cancerous stomach ulcer exacerbated by the arsenic in his wallpaper. Napoleon was not alone in his suffering. 

The Victorian women that I thought were malingering invalids when I first saw a fainting couch, were actually victims of their bowers. In his book, At Home: A History of Private Life, Bill Bryson writes that by the late 19th century, 80 percent of English wallpapers contained arsenic, often in significant quantities. Between wallpaper glues, arsenic, and lead, the home percolated with dangerous chemical compounds.

Poisonous walls are not the only time walls have been the cause of human suffering. Many infamous border walls, like the Berlin Wall and the Great Wall of China prove fatal vis-à-vis geopolitical violence.

Lithuanian-born Walter Heike concluded his resume by stating, “ I am also keen on learning and further education. I have many diverse cultural interests." It was likely these interests, notoriously hard to realize in East Berlin, that drove Heike to flee for the West. Unfortunately for Hieke, this was not to be. On June 22, 1964, while trying to get past the Berlin Wall, a border guard shot and killed the 29-year-old on the grounds of the Invaliden Cemetery.

Hieke was just one of the 260 people that were killed or died in other ways directly connected to the GDR border wall between 1961 and 1989. Another young man, Wolf-Olaf Muszynski, who shares my February 1st birthday was one of many unfortunates who drowned in the Spree river while trying to escape. Residents found Muszynski’s body not far from the Oberbaum Bridge on the West Berlin Spree riverbank. Nothing is known about why he chose to flee. 

Construction work on the Berlin Wall at the Brandenburg Gate

While it is difficult to find numbers on just how many people have died because of the Great Wall, it is estimated that over 300,000 Chinese laborers died during its construction. This figure doesn’t take into account how many marauders, soldiers, and guards died as a result of the wall––nor does it count the Chinese lovers who blew themselves up with a suicide bomb while visiting the wall back in 1988.

Border walls such as the Berlin Wall and The Great Wall are anathema to human cooperation, and ingenuity––and are instead a physical representation of hostility, nationalism, and anti-immigration sentiment. These are walls at their very worst, encircling bad ideas and geopolitical malfeasance. A more recent example of this is the wall called for by Donald Trump and his supporters during (and after) his presidency. Far from being an “impenetrable, physical, tall, powerful, beautiful” wall, it was a manifestation of xenophobia, racism, and derision. Fortunately, this wall was never fully constructed, and by the time Biden took office in 2020 halting the project, only 458 miles had been built and much of it was cheap fencing and rudimentary barriers. Even so, this wall caused lasting political injuries, and the hostilities it provoked shut down the National Butterfly Center in Mission Texas.

This goes to show that geopolitical, cultural, and psychological walls can fatally undermine human decency. After all, arsenic doesn’t hold a candle to human animosity (unless the two overlap and result in homicide).

Living Walls

Of course, walls are not always bad. They showcase our petroglyphs, family photos, murals, maps, and frescoes. They protect us from exposure and provide privacy from our neighbors. Roofs would certainly make less sense without them. Some of humanity’s greatest innovations have to do with walls. 

Our ability to live in a variety of hostile environments sets us apart from many other species. We have figured out how to provide ourselves with livable ambient temperatures in extreme environments like Saudi Arabia or on top of fault lines like in San Mateo, CA. We owe much of our environmental versatility to the structures we build. 

The San Andreas fault line slithers underneath the Californian coast like a slumbering eel––occasionally shuddering the ground above with earthquakes. To combat this shaking, which can bring down houses and other infrastructure, engineers, architects, and builders have learned how to seismically retrofit homes. The Cripple Wall is the most common way this is done. This process creates a crawl space between the home’s first floor and foundation. This area, supported by plywood braces that connect both the house to the foundation and the Cripple Wall to the house, prevents the house from sliding off its foundation and absorbs some of the shifting motion from the quake. 

While some might find the name objectionable, the Cripple Wall is a wall worthy of praise. It is a consummate example of human resilience and technical innovations as is another wall worth mentioning.

Vertical hydroponic and aquaponic walls blend the line between wall and garden. Like something out of Jack and the Beanstalk, plants grow vertically in PVC pipes, hollow sticks, or mesh pockets. Aquaponics is done over a fish tank in a symbiotic recirculating system that cycles nutrients between the flora above and the fauna below. Even more dazzling than Scheele’s Green, lettuce and arugula bathe these walls with a verdant glow as they grow. Edible walls such as these are not only pretty but could provide a sustainable solution to overcome the looming food crisis. Addressing food shortages and supply-chain crises necessitates growing more food in urban areas. However, this requires space. Just as high-rises and sky-scrapers optimize space for humans living in the city, vertical gardening could optimize space for urban agriculture. Studies have shown that if pumping and lighting requirements are met, vertical agriculture is a viable and aesthetically pleasing remedy to food insufficiency.

Vertical agriculture vegetable wall
                                                                                                             

When the Berlin Wall came down in 1989 political scientist Francis Fukuyama famously declared that the moment marked the “end of history.” Even so, and luckily for the living, history continues to unfold, and walls with it, extending our metaphors, poetry, and politics, exploiting our faults, and paying homage to our ingenuity.