Roofing operations involving open flames or hot processes present a significant fire hazard. Ignition sources include heated kettles of tar and asphalt, open flame torches and hot-air guns. The installation of torch-applied roofing systems can be particularly hazardous. Torching can reach temperatures over 1000°C (1800°F). Roofers may suffer serious burns from the torch or the hot modified bitumen they are applying. In addition, temperatures generated by torching applications have been known to start fires that may smolder out of sight, only to burst into flame later, well after torching is over.