Living Smart

III SCIENCE & STEM EDUCATION 082 083 Take care or bang goes party season Dr. Jason CHAN Lecturer I, Department of Chemistry C hristmas, the party season for many Hong Kong youngsters, is just around the corner. Many may even have plans for a pre-Christmas celebration party this weekend. While celebrations of the festival are worth looking forward to, partygoers should be aware of safety while they are next to some cozy Christmas fireplace. A group of local university students were caught off guard by a dust explosion that happened during a birthday party a few weeks ago, injuring a dozen people. This unfortunate incident startled the city as many of us would wonder how such incidents could happen in such a seemingly ordinary setting. Dust explosions, as we know, are the result of the rapid firing of combustible fine particles being suspended in air, often in an enclosed environment. Fuel, oxygen and an ignition source are required in a proper combination before a fire can occur – which were all unfortunately present in the aforementioned birthday party. When combustible materials are reduced to a fine powder form (which, in this case, was flour), the small sizes of the particles increase their surface area dramatically, enabling rapid combustion to take place when they become dispersed into the air, even when the material in bulk form is not easy to set alight. When the powder become suspended in the air, any small fire source (in this case, a candle flame) is more than enough to cause each of these small particles to catch fire in the blink of an eye.