From the archives: The asbestos times
How asbestos saved cities, before we realized its risks
Mano Majumdar writes about the rise and fall of asbestos for Issue 13. Read it online here.
Few materials fell from grace like asbestos. Once cherished as an almost-magical material, it is now the archetypal carcinogen. We spent over a century integrating it into buildings, wiring, pipes, brake pads, and more, and we now spend billions of dollars a year removing it.
But the standard story of asbestos as a mistake – or even a crime – of massive proportions does not do justice to the real benefits it brought. Asbestos was central to mitigating urban fires, which cost thousands of lives each year as modern cities grew larger, denser, and more flammable. But as we learned to control urban fires without it, asbestos’s health costs seemed less and less worth bearing. Asbestos is in its final days and soon the material will almost disappear entirely.
Miracle materials are not all manmade. Asbestos is a family of six naturally occurring silicates, made from the same elemental blocks as sand or glass, organized in delicate fibrous strands that tease apart like cotton candy and compare with steel in tensile strength. Chrysotile or white asbestos, the commercially dominant form, is a serpentine silicate, with fibrous strands that crumble to the touch; the remaining five are amphiboles (including crocidolite, blue asbestos), spiky forests of short and fragile needles. In all its forms, asbestos has remarkable properties: it’s light, waterproof, and, most famously, fireproof.
The unique structure of asbestos requires a unique set of circumstances to form. The fibers of asbestos are crystals precipitated out of a solution of minerals in hot water under pressure. This is hydrothermal synthesis, a process used to grow artificial crystals in laboratory settings (or candy from syrup). The low-silica rocks in which asbestos originates are found naturally across the planet, and asbestos has been found and mined on every inhabited continent.
The first written record of asbestos was by Theophrastus, who categorized it correctly by including it in his mineralogical work, On Stones. He did better than most, considering that an animal origin for asbestos was a common misconception in the ancient world: asbestos was credited to everything from phoenix feathers to the mythical salamander to Princess Bride–style literal volcano-dwelling fire rats.
Its rarity and invulnerability to fire gave asbestos an air of mystique and an association with power. Charlemagne is said to have had a tablecloth of pure asbestos that he would throw into the fire as a party trick, and Emperor Ashoka of India sent a gift of asbestos cloth to Sri Lanka. Earnest pilgrims into the Holy Land were sold pieces of asbestos cloth as remnants of the Holy Shroud, made credible by their immunity to fire. Benjamin Franklin paid for his time in Europe by selling an asbestos purse to a collector (for which he was paid ‘handsomely’). Yet asbestos existed only as an interesting novelty without a clear use.
You can read the rest of the piece here.
