Triboemission of nanoparticle aerosols from construction materials is a growing concern due to its potential impact on air quality and human health. In this study, we investigated the effect of aggregation of polyurethane fibers (PUFs) proceeding from waste on the kinetics of triboemission in cement mortars. A quantitative methodology was employed to assess the deposition rate, particle size distribution, and emissivity for the aerosols within the particle aerodynamic diameter range of 10–400 nm. The triboemission properties were correlated with the pore structure, morphology and tribochemical transformations of the particles and worn surfaces. Our results highlight the intricate influence of PUF aggregation on the kinetics of triboemission in cement mortars through both direct and indirect mechanisms and provide valuable insights into the mechanisms governing triboemission in construction materials.