Historic battle flags and uniforms are collected by museums, and many have significance as icons representative of their owners as well as historic context. The effects of battle, both mechanical and chemical, have an impact on the projected lifetimes of these objects in museums. Modern air quality, as well as the type of display, is important. Pyrotechnic displays using Black Powder can also produce considerable amounts of particulates and gases and, if near museums, may be a significant source or damage to a museum's collection.