Airborne particulates present a potential hazard to health in a variety of indoor workplaces, from offices to the manufacturing floor. Dust and aerosols are two of the most common occupational risk factors in the workplace worldwide. It is very important to understand when it is sufficient to describe dust exposure only by given mass concentration that dust particles could be in the nanosized range in the workplace air even for brief exposures, such as welding aerosols. The main objective was to assess total dust and nanoparticle concentrations in the selected workplaces and to evaluate their impact on workers’ health. This project describes nanoparticle concentrations and their potential impact on workers’ health considering the exposure levels in three workplaces. Industrial and non-industrial environments have been included in the project. The office environment was used as an indicator for the background level of comparison with the metalworking and woodworking industries for measurements of dust particles including the nanoscale particles (> 100 nm). Fraction size of the samples according to a dispersity of > 10 μm, 0.25–10 μm, < 0.25 μm, and 1–100 nm was analysed in order to describe the particles’ chemical composition at the different stages. The worst working conditions (the smallest particles, 12 nm), the highest total dust concentrations, and the lowest difference between total inhalable particle and nanoparticle concentrations were detected among woodworkers. These findings provide a basis on how to evaluate nanoparticle exposure and its impact on workers’ health because the highest immune cell counts and relatively high IL-6 expression were observed among woodworkers compared with the other groups. The data show a negative tendency of nanoparticle exposure concentrations on workers’ health based on the increase of inflammatory processes and damage to airway epithelial cell functionality.