Air fryers are a recent trend in home cooking that offers several unique advantages. However, what most people don't know is that they actually work the same as a convection oven. The only difference is that they're much smaller. This means that the heating element contained in air fryers and ovens can burn cardboard. So be sure to keep any excess packaging far away! The same is true of toaster ovens. Most designs include heating elements on the upper or lower surface of the oven. These can be even more dangerous as the cardboard risks coming into contact with them.