Class 4 laser beams represent a fire hazard and under some situations it is possible that Class 3 lasers can initiate fires. Use flame retardant materials wherever applicable with all laser applications. Users should be aware that opaque laser barriers, e.g. curtains, can be designed to offer a range of protection, however, they normally cannot withstand high irradiance levels for more than a few seconds without some damage, e.g., production of smoke, open fire, or penetration. Operators of Class 4 lasers should also be aware of the ability of unprotected wire insulation and plastic tubing to catch on fire from intense reflected or scattered beams, particularly from lasers operating at invisible wavelengths. Contact SU Fire Marshall’s Office for additional guidance.