Pyroclastic flows are extremely dangerous due to their high speed and temperatures reaching up to 1,000 degrees Celsius. They can move at speeds up to 700 km/h, making them impossible to outrun. Pyroclastic flows also contain hot gases, ash, and rock fragments, which can cause severe burns, respiratory issues, and bury everything in their path. Additionally, pyroclastic flows can travel downhill and spread over large areas, causing destruction to anything in their way.