Exposição ocupacional a poeiras em marmorarias: tamanhos de partículas caracteristicos

Abstract

The main occupational hazards found in workplaces include dust exposure, facilitating the increase of respiratory diseases, of which silicosis is the most important. Due to the importance and gravity of the occupational exposure to dust and to the high number of workers exposed, the aim of this paper was to study the characteristics of this exposure in the ornamental stone works. This study was based on the application of new conventions adopted internationally by the American Conference of Governmental Industrial Hygienists (ACGIH), International Organization for Standardization (ISO) and Comité Europeén de Normalisation (CEN) for the classification of types of dust by particle size range. The occupational exposure characterization took into consideration the relations between and among dust concentrations in workplaces, the types of rocks worked on, wet and dry operations, the machinery and tools used and the size distribution of particles suspended in the air, with the use of state-of-the-art sampling and measuring instruments. The samples were analyzed using the techniques of gravimetry, X-ray diffraction, optical microscopy, scanning electronic microscopy and particle analysis by the time-of-flight technique. The workplaces of the stone works were characterized by high concentrations of dust in all the sampled fractions (inhalable, thoracic and respirable), produced by the tools used in the dry abrasive polishing sector. The silica concentrations were up to 16 times higher than the maximum value recommend by ACGIH in 2004. The preponderant average aerodynamic diameter presented by the particles sampled at the stone works was between 2.2 and 3.9 m, corresponding to the range of highest alveolar deposition, and therefore, to the greatest risk of acquiring silicosis and lung cancer. The evaluation of a stone works that adopted the wet abrasive polishing process with pneumatic sanders showed that the probability of environmental concentrations exceeding the occupational reference values for the inhalable and respirable fractions could be reduced by up to 99%. Likewise, wetting at the dust generation source showed a 93% reduction in the quantity of particles suspended in the air, in comparison to the stone works that operated with dry abrasive polishing.