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  • Risk assessment of welding operations and processes in terms of ultrafine particles emissions
    Publication . Gomes, João; Miranda, Rosa M.; Esteves, Helder M.; Albuquerque, Paula
    Welding is extensively used in metallic construction worldwide, in spite of being able to produce dangerous fumes that may be hazardous to the welder’s health. It is estimated that, presently, 1-2% of workers from different professional backgrounds (which accounts for more than 3 million persons) are subject to welding fume and gas action. Recently, studies have proved the existence of ultrafine particle emissions, from welding processes, thus increasing the health risks to exposed welders. In particular, it was found that the amount of emitted particles (measured by particle number and alveolar deposited surface area) is clearly dependent on the distance to the welding front, and also on the main welding parameters, namely the applied current intensity, heat input, nature of base metal, nature of addition metal, and nature of welding gases used. The emission of airborne ultrafine particles increases with the increase of current intensity as the fume-formation rate does. In regards to welding gas mixtures, higher emissions are observed for more oxidant mixtures, that is, mixtures with a higher CO2 content, which result in higher electric arc stability. These mixtures originate higher concentrations of ultrafine particles (as measured by the number of particles per cm3 of air) and higher values of the alveolar deposited surface area of particles, thus resulting in more severe worker exposure. Combining the obtained data, it is possible to compare different welding processes and operating conditions, in order to assess different levels of welder’s exposure. Also, the graphical representation of measured concentrations of airborne ultrafine particles, with time and distance, allows us to define “safe” and “critical” regions within a welding workshop in terms of welder exposure. This information may be combined with the results of risk analysis derived by control banding and helps to categorize the sites where regulatory measures such as operation containment or dedicated exhaust ventilation need to be implemented.
  • Characterization of airborne emission of nanoparticles in the ceramic industry in Portugal
    Publication . Esteves, Hélder; Bordado, J.; Gomes, João; Miranda, R.; Albuquerque, Paula
    The objective of this study was to evaluate occupational exposure to nanoparticles during some tasks performed in different production processes of different ceramic industries in Portugal, to select the places of greatest occupational exposure through the analysis of the sampled data, to verify what is the pulmonary accumulation in these places, to identify the composition of the released nanoparticles, apply a Control Banding Tool and try to understand which companies require more risk control measures. The study was carried out in three different national ceramics production industries, one for sanitary ceramics production, another for porcelain crockery production and finally another for the production of ornamental crockery (red paste). It is concluded that occupational exposure values to nanoparticles are high in all cases and that nanoparticles are very small in size (11.5 to 15.4 nm). Existing risk control measures are insufficient and verified risk levels are high (Risk Level 3 and 4). The chemical composition of the analyzed nanoparticles is similar regardless of the typology of the ceramic production plant and their chemical composition as a percentage of certain materials has a direct influence on crystallinity.
  • Characterization of airborne emission of nanoparticles in the ceramic industry in Portugal
    Publication . Esteves, H.; Bordado, J.; Gomes, João; Miranda, R.; Albuquerque, Paula
    The objective of this study was to evaluate occupational exposure to nanoparticles during some tasks performed in different production processes of different ceramic industries in Portugal, to select the places of greatest occupational exposure through the analysis of the sampled data, to verify what is the pulmonary accumulation in these places, to identify the composition of the released nanoparticles, apply a Control Banding Tool and try to understand which companies require more risk control measures. The study was carried out in three different national ceramics production industries, one for sanitary ceramics production, another for porcelain crockery production, and finally another for the production of ornamental crockery (red paste). It is concluded that occupational exposure values to nanoparticles are high in all cases and that nanoparticles are very small in size (11.5 to 15.4 nm). Existing risk control measures are insufficient and verified risk levels are high (Risk Level 3 and 4). The chemical composition of the analyzed nanoparticles is similar regardless of the typology of the ceramic production plant and their chemical composition as a percentage of certain materials has a direct influence on crystallinity.