What Causes Sugar to Explode?

The cobwebs in your mind have barely vanished as the refrigerator door swings closed with a lazy motion, and you sit down at the breakfast table. The coffee is still brewing, and you're barely awake. You read the newspaper as you pour your whole grain cereal into your bowl, add milk, and heap spoonfuls of refined sugar. As you scrape the last bit of sugar from the bowl, the spoon taps against the porcelain, and — BOOM?

Gallery of Building Explosion Images

Does this sound like an unbelievable story? It certainly does. However, the reality is that sugar can actually pose a serious threat—not to consumers, but to those working in the refinery industry.

The hidden peril linked to sugar refinement gained worldwide attention on February 7, 2008, when the Imperial Sugar Company refinery in Port Wentworth, Georgia, erupted in a violent explosion. Authorities suspect that an accumulation of sugar dust ignited and caused the catastrophic event [source: CNN].

Georgia's Fire Commissioner, John Oxendine, referred to the explosion as 'the worst industrial accident' of his 14-year tenure [source: Reuters]. The blast was so powerful it destroyed entire parts of the refinery, exposing steel beams and concrete foundations. Seven workers tragically lost their lives, while twenty others suffered severe burns, with 17 of them placed in medically induced comas [source: Houston Business Journal].

How can sugar cause such a deadly explosion? How can it devastate steel and concrete? Learn more about the science of sugar explosions on the following page.

Sugar: A Natural Explosive

While it's not something we often consider, sugar is actually flammable. Just think about the mishaps some have had when trying to caramelize a crème brûlée. A flaming marshmallow is another clear example of sugar burning. However, marshmallows don't explode. If they did, we'd need an entirely different treat at campfire gatherings. So, why does sugar explode?

In reality, there's nothing extraordinary about sugar that makes it flammable. Before the Imperial Sugar refinery explosion, there had already been 281 dust explosions in the U.S. between 1980 and 2005, resulting in 119 fatalities. These explosions were caused by dust from various materials like grains and wood [source: Chemical Safety Board].

"Any organic material can burn," explains Dr. Steve Brown, a chemistry professor at the University of Arizona. But for an explosion to occur—especially with volatile substances like sugar dust—several specific conditions must be met.

Picture yourself in a room covered in a thick layer of sugar dust. You slap your hand onto a table, sending some of the dust into the air. If you carelessly strike a match, you'd witness an explosion unfold in slow motion. What might seem like a single, instantaneous flash is actually a chain reaction, where one ignited sugar dust particle sets off the next, and so on. The entire process is fueled by oxygen in the room, and because the dust is airborne, it interacts with the oxygen far more easily than if it were settled on a surface. This is also why marshmallows don't explode—there's not enough oxygen for the sugar inside to interact with [source: CNN].

The intensity of the explosion is influenced by the size of the space. As sugar dust particles ignite, they trigger a chain reaction that releases energy. This energy creates compression, causing the air to expand. When this buildup outpaces the rate at which the flame burns—especially in confined spaces—the result is an explosion.

The first explosion is known as the primary explosion, and it can disturb additional sugar dust, sparking a secondary explosion. These blasts can occur rapidly in succession, with the second often being the more powerful. As Phil Choven of the Fire Department Safety Officers Association puts it, "It's kind of like, boom-KABOOM!"

The likelihood of a room filled with sugar dust exploding also depends on several factors. One of the key variables is the size of the dust particles. According to the National Fire Protection Association, particles must be at least 420 microns in size to be considered volatile. Although this may sound tiny, it's actually over four times the size of a typical grain of table salt. Furthermore, even a small amount of dust can be dangerous. The NFPA notes that just 1/32 of an inch of volatile dust covering 5 percent of a room's surface area "presents a significant explosion hazard" [source: Chemical Safety Board].

Given the massive amount of sugar dust generated during the refining process, it's hard to imagine the explosion at the Imperial Sugar refinery wasn't caused by dust. Additionally, Choven emphasizes that a sugar refinery couldn't use the usual method of humidifying rooms to control volatile dust, as wet sugar would clog up the machinery.

To learn more about explosions and related topics, follow the links below.