AIRBORNE DUST CHARACTERIZATION IN HARSH ENVIRONMENT

Dust generated during ornamental stone transformation process is considered one of the most risky factors for the health of workers employed in the stone industry. Workers are strongly exposed to high dust generation mainly during manual working actions, especially those belonging to the finishing stage of the production cycle. During such operations the tools are handled directly by the workers without the use of water. As a consequence, the generated dust circulates in the working environment directly influencing the breathing zone of the workers. In this paper the results obtained from a dust collection analysis campaign, carried out in an ornamental stone conversion industry, are analyzed and discussed in order to define the best strategy to reduce the amount of produced dust during hand working actions and to improve the air quality of working environment. The tests have been carried out inside an aspirating cabin equipped with an innovative filtration system and an “on-line” control logic for dust sucking architecture. Different types of ornamental stones have been selected for the tests (granite, limestone, sandstone, etc.). Dust concentration has been determined collecting the inhalable fraction by personal samplers directly mounted on the worker performing manual edge polishing. In addition, a laser diffraction system has been utilized to perform airborne dust size class distribution analysis in order to derive information concerning dust characteristics, optimizing this way the selection of the filtering media and the operative conditions of the aspirating cabin. The goal of such analyses was to verify the impact of the aspirating device with both the old and the new configuration. The results shown as the filtration system installed in the cabin considerably reduce the quantity of airborne dust and has an appreciable impact over the size class distribution of generated dust according to the settings of the cabin.