As the fire grows higher and hotter, more flammable objects and furnishings will ignite from spreading flames, including wooden cabinets and countertops, wallpaper, hanging baskets, and curtains. With the fire moving beyond the stovetop and other areas beginning to burn, a denser plume of hot air and smoke rises and spreads across the ceiling.
If you're still in the room, this hot, smoky air can instantly burn the inside of your breathing passages. Plus, fires generate highly poisonous gases, including carbon monoxide and hydrogen cyanide (created when insulation, carpets, clothing, and plastics burn). Just two or three breaths of it and you could pass out.