an evaluation of available measurement methods for continously monitoring the number and mass of carbon fibers emitted from source operations was conducted. a total of eleven candidate monitoring methods were identified based on contact (electrical), locally sensing (optical, microwave) and remote sensing (microwave, radar) each method was rated on the basis of measurement (sampling), detection and instrumental parameters, and their useful concentration and length range were compared to three emission scenarios representing textile weaving, machining and waste incineration. five methods have merit for certain conditions and are recommended for further study: for moderate to high concentrations and lengths greater than 1 mm. microwave-osgef and electrical grid-arc methods; for moderate to high concentrations and lengths less than 1 mm, optical scattering-rotating lens and fiber aerosol monitor (fam) methods; and for very high concentrations in absence of other particulate matter (i.e., process upset), the optical-led method microwave-osgef is the only method that is specific to carbon fibers alone. the electric grid-arc method can be arranged to sample a major portion of the air stream, providing representative sampling. these two methods are recommended as having highest priority for further development