The use of asbestos, once celebrated for its versatility and fire-resistant properties, has left a lasting legacy of environmental degradation and public health risks. This paper provides a comprehensive assessment of the environmental impacts and health risks associated with asbestos, highlighting its widespread use, environmental persistence, and adverse effects on human health. Through a literature review, this study examines the historical context of asbestos use, its adverse environmental effects and the mechanisms by which exposure to asbestos poses significant health risks, including the development of asbestos-related diseases such as mesothelioma, lung cancer, asbestosis, etc. It also assesses the current regulatory framework and provides a methodological analysis of the strategy for recycling end-of-life materials containing asbestos fibers, proposing the inclusion of asbestos-containing materials (ACMs) in the rock wool industry to reduce Greenhouse Gasses (GHG) emissions. Drawing on interdisciplinary insights from environmental science, public health, and regulatory analysis, this paper concludes with recommendations for improving asbestos management strategies, promoting safer alternatives and mitigating the long-term environmental and human health impacts of asbestos.

Sm_2−xCa_xZr₂O_7−x/2 (x = 0, 0.05, 0.1) and Gd_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1) mixed oxides in a pyrochlore–fluorite morphotropic phase region were prepared via the mechanical activation of oxide mixtures, followed by annealing at 1600 °C. The structure of the solid solutions was studied by X-ray diffraction and refined by the Rietveld method, water content was determined by thermogravimetry (TG), their bulk and grain-boundary conductivity was determined by impedance spectroscopy in dry and wet air (100–900 °C), and their total conductivity was measured as a function of oxygen partial pressure in the temperature range: 700–950 °C. The Sm_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1) pyrochlore solid solutions, lying near the morphotropic phase boundary, have proton conductivity contribution both in the grain bulk and on grain boundaries below 600 °C, and pure oxygen–ion conductivity above 700 °C. The 500 °C proton conductivity contribution of Sm_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1) is ~ 1 × 10⁻⁴ S/cm. The fluorite-like Gd_2−xCa_xZr₂O_7−x/2 (x = 0.1) solid solution has oxygen-ion bulk conductivity in entire temperature range studied, whereas proton transport contributes to its grain-boundary conductivity below 700 °C. As a result, of the morphotropic phase transition from pyrochlore Sm_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1) to fluorite-like Gd_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1), the bulk proton conductivity disappears and oxygen-ion conductivity decreases. The loss of bulk proton conductivity of Gd_2−xCa_xZr₂O_7−x/2 (x = 0.05, 0.1) can be associated with the fluorite structure formation. It is important to note that the degree of Ca substitution in such solid solutions (Ln_2−xCa_x)Zr₂O_7−δ (Ln = Sm, Gd) is low, x < 0.1. In both series, grain-boundary conductivity usually exceeds bulk conductivity. The high grain-boundary proton conductivity of Ln_2−xCa_xZr₂O_7−x/2 (Ln = Sm, Gd; x = 0.1) is attributable to the formation of an intergranular CaZrO₃-based cubic perovskite phase doped with Sm or Gd in Zr sublattice.

The circular economy emphasizes reducing, recycling, and reusing waste, a principle that is challenging to apply to hazardous materials like asbestos-containing construction waste, typically destined for landfills due to limited recycling options. This experimental study investigates the physicochemical characterization of asbestos fibers in fiber cement boards and assesses the efficacy of mechanical grinding and thermal treatments to transform these fibers into non-fibrous, stable phases for reuse in sustainable construction applications, such as cement and mineral wool production. Using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), we analyzed samples from end-of-life fiber cement panels, subjecting them to thermal treatments at 700 °C, 1000 °C, and 1200 °C. Results show that, while grinding reduces particle size, it does not eliminate fibrous structures; however, thermal treatment above 1000 °C fully converts chrysotile into forsterite and enstatite, eliminating health risks and enabling material reuse. These findings, that are part of the FiberRec project, support a systematic approach to integrating asbestos-containing waste into a closed-loop material cycle, significantly reducing carbon emissions and landfill dependency.

The circular economy is strategically based on the three R's policy: reduce, recycle and reuse, which is not easy to apply to waste for which there are no processes that allow them to be recycled, or others for which reuse is not possible. One group of wastes that is particularly problematic because of its volume, quantity and diversity is the group of construction and demolition materials, including fibrous materials such as asbestos, for which there are still no clear alternatives for reintroduction into the supply chains of new processes. The destination of these end-of-life materials is landfill, with all the well-known drawbacks of limited landfill space, the high volume of material to be landfilled and the associated costs. In order to promote the reuse of asbestos fibres, it is essential to characterise them in physico-chemical terms and to assess how effectively mechanical and thermal treatments can transform these fibres for reuse, in order to provide the basis for a systematic approach to the incorporation of asbestos-containing waste into new construction applications. This analysis focuses on sustainable construction practices aimed at reusing waste materials to achieve significant reductions in carbon emissions over the entire life cycle of buildings.