Difference in Density of Fiber Bundles Exposed on Surface of Asbestos-Containing Materials--with the Aim to Reduce Time Necessary for Visual Observation

摘要

It is possible that asbestos-containing materials (ACMs) are contained in construction and demolition waste (CDW) that is transported to an intermediate treatment facility. Therefore, a rapid method of detecting asbestos fibers at an intermediate treatment facility for CDW is required. Although a visual observation method has been developed for rapid determination, the time required to determine should be shortened further. If asbestos fibers on a certain part of the surface of CDW particles could be detected visually and observation of the other areas could be omitted, the time necessary for the observation can be shortened. In this study, the determination error rates for a certain part of the surface and the entire surface were estimated. A CDW particle whose surface remained intact when the construction material was produced, was classified as an intact-surface CDW particle. A CDW particle that chipped off when the construction material was demolished or shredded, was classified as a broken-surface CDW particle. Observation of only the broken surface yielded similar results to observation of the entire surfaces of non-ACMs and ACMs. For non-ACMs, the determination error rate for observation of one-half of the broken surface was 1.6%, whereas that for observation of the entire broken surface was 2.2%. For ACMs, the determination error rate for observation of one-half of the broken surface was 0.16%, whereas that for observation of the entire broken surface was 0%. From the obtained error rates, it was found that the time necessary for observation can be shortened.