Experimental Evaluation of Asbestos Fiber Dispersion from Degraded Asbestos‑Cement Materials Under Simulated Handling Scenarios

The presence of asbestos-containing materials in the existing building stock continues to pose a major occupational health risk, particularly in the context of renovation, maintenance, and demolition activities. Although the use of asbestos has been banned across the European Union, numerous construction elements made of asbestos cement remain in service, and their degradation can promote the release of respirable fibers into the air. The aim of this study is the experimental evaluation of asbestos fiber dispersion as a function of material condition and the type of mechanical stress applied, under controlled laboratory conditions.
The methodology involved testing asbestos-cement samples classified according to their degree of degradation (intact and degraded) in three simulated scenarios: static handling, dry manual cutting, and mechanical impact. Airborne fiber concentrations were determined by phase-contrast optical microscopy (PCM), in accordance with the NIOSH 7400 method, used as an index method, while identification and morphological characterization were carried out by electron microscopy (SEM/EDX and TEM), in compliance with ISO 14966 and ISO 10312 standards.
The results highlight a significant increase in fiber dispersion with increasing mechanical stress, with the highest values associated with cutting and impact scenarios. Degraded samples consistently exhibited higher emission levels than intact ones, confirming the critical role of cement matrix degradation in fiber release. Granulometric analysis indicated a predominance of respirable fibers, with dimensions favorable for penetration into the lower respiratory tract. In addition, the temporal dynamics of dispersion revealed the existence of a critical interval immediately after the initiation of mechanical stress, characterized by peak concentrations.