 Victoria is one of the most bushfire-prone parts of the world. Every summer bushfires threaten properties and lives. But did you know it's not the flames that kill most bushfire victims? No, it's the radiant heat. Most victims die from the effects of radiant heat, long before they're reached by the flames. Radiant heat is what you feel when you sit next to a campfire. If a campfire heats up to 2 kilowatts per square meter, you'll feel that it's too hot and will want to move back from the fire. If you don't, this amount of radiant heat is enough to cause burns and blisters in as little as 40 seconds. At 12 kilowatts, it can cause some materials like dry timber to ignite. A bushfire can reach 100 kilowatts and the effects can be truly catastrophic. For humans, radiant heat can cause burns from 100 meters away and cause a dangerous increase in body temperature. Radiant heat can cause the rapid onset of heat stroke. Heat stroke damages your brain, meaning you won't be able to concentrate to make good decisions as the fire arrives. Other impacts include severe damage of internal organs and death. There are some things you can do if you're caught in a fire. Cover your skin with long-sleeved natural fibre clothing like wool. It's also useful to know that radiant heat only travels in straight lines and can't bend around corners. So, sheltering behind or inside solid structures may help protect you. But be aware radiant heat will travel straight through glass. The best defence against radiant heat is a simple one. If you're not anywhere near a bushfire, its radiant heat can't hurt you. Leaving early is always your safest option.