They tied pillows to their heads and walked out under the falling stone. It worked.
The most famous protective equipment of the eruption appears in Pliny the Younger's account of his uncle's last night at Stabiae: when the household finally abandoned the buildings for the open beach, “they tied pillows on their heads as protection against the falling objects.” As engineering, it was reasonable. Pumice is frothed volcanic glass, light enough to float; what fell on Campania that day bruised and battered and occasionally knocked people down, but a bound cushion genuinely blunted it. The pillow-helmets are a snapshot of people solving, competently, the hazard they could see and feel: things falling from above.
The hazard that killed nearly everyone who stayed did not fall at all, and gave no comparable warning to reason from. When the eruption column collapsed, it sent pyroclastic surges along the ground — avalanches of gas and ash at roughly 250 to 500 degrees Celsius, moving at highway speeds. Volcanological studies of the Pompeii victims concluded that heat, not suffocation, killed most of them, and killed them in moments; many of the dead show no defensive contortion at all, frozen mid-posture. Against that, cloth, cushions, walls, and distance-within-the-city were all the same answer: none.
Pliny the Elder wore the improvised armor himself, pillow and cloth, down to the Stabiae shoreline — and died there anyway, apparently of the fumes or a failing heart, the one man in the party the protective gear could not have saved from the hazard that actually reached him. The pillows did their job. The job was never the problem.
Hurricane preparation has its own version of the pillow helmet: plywood nailed over the windows. It isn't a foolish measure — boarding up genuinely protects against what people picture when they imagine a hurricane, which is wind and flying debris. That is exactly what makes it a trap. Doing something that visibly works against the danger you can see convinces you the storm has been handled, so you stop preparing for the danger you can't see — and the danger you can't see is the one that kills. The National Hurricane Center's fatality data is blunt about this: between 2013 and 2022, water — storm surge and flooding — caused about 86 percent of direct U.S. hurricane deaths, against 12 percent for wind. That is roughly seven people drowned for every one killed by the hazard everyone boards up against. Plywood keeps out nothing that rises from the floor. The only defense against the water is the one decision plywood quietly talks people out of: not being in the house when it arrives. Stabiae ran on the same logic with different materials — the pillows handled the falling stone honestly and completely, and their success helped a beach full of people feel equipped for a night whose real killer hadn't shown itself yet.
The pillows were rated for stone. Nothing they owned was rated for the air.