Disclaimer: Do not try this at home!
Powdered sugar seems to be the epitome of innocence, as far as food goes—sweet, delicate, and perfect for dusting off chocolate cupcakes. But in reality, powdered sugar can be dangerous, not just because it is addictive. If too much powdered sugar becomes airborne, it can react with the surrounding air extremely quickly and cause a gigantic explosion.
The inside of macroscopic particles can only react when there is surface available for reaction. When sugar is in large chunks, like sugar cubes, there is not enough surface area to spark any sort of reaction. However, in a powdered form, the surface area increases, making more particles available for collision with surrounding molecules in the air. This increases the reaction rate, making the sugar highly flammable. When there is a high enough concentration of sugar in the air to form a fine mist, the presence of just a small spark can cause an explosion. Demonstrations like the one above can create a respectable explosion simply by quickly shooting large quantities of powdered sugar into a small volume of air.
Unfortunately, sugar explosions are no joke and would not be a good experiment to play around with. In February 2008, the Imperial Sugar Company in Port Wentworth, Georgia, exploded due to massive accumulations of sugar that had spilled from the equipment in the packaging building. The building was demolished, thirty-eight people were injured, and fourteen more were killed. While such accidents are easily avoidable with improved ventilation, not much progress has been made in codifying such preventative measures.
It is not just sugar, either—many seemingly harmless substances, such as flour, sawdust, pollen, or even tea, will go into flames as powders, sometimes creating even bigger explosions than the ones caused by sugar. Industrial materials, too, such as coal and aluminum, become exponentially more dangerous in powdered form. If a piece of machinery in a factory backfires, it may only send up a small spray of sparks, which may not be a huge concern in itself. However, if there is too much accumulated dust, even a small malfunction can create enough turbulence to whisk the surrounding dust into the air. This can ignite a chain reaction of explosions, each one growing in size as more and more dust gets stirred up.
As long as people are responsibly managing dust levels, it is unlikely that sugar or flour or any dust will have time to build up to reach explosive levels, so there is no need to worry that the bag of powdered sugar sitting in the pantry will spontaneously burst into flames. However, there is no doubt that powdered sugar, if allowed to accumulate, can be a powerful weapon of destruction.
Moreau-Eraso, Rafael. “The Danger of Combustible Dust.” The New York Times, 22 August 2014, https://www.nytimes.com/2014/08/23/opinion/the-danger-of-combustible-dust.html. Accessed 18 February 2021.
“Imperial Sugar Company Dust Explosion and Fire.” CSB, 2014, https://www.csb.gov/imperial-sugar-company-dust-explosion-and-fire/. Accessed 18 February 2021.
Casal, Joaquim. “Dust Explosions.” Science Direct, Elsevier B.V., 2021, https://www.sciencedirect.com/topics/chemical-engineering/dust-explosion. Accessed 18 February 2021.