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- Risk assessment of welding operations and processes in terms of ultrafine particles emissionsPublication . Gomes, João; Miranda, Rosa M.; Esteves, Helder M.; Albuquerque, PaulaWelding 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.
- Determination of airborne nanoparticles in elderly care centresPublication . Almeida-Silva, Marina; Almeida, Susana Marta; Gomes, João; Albuquerque, Paula; Wolterbeek, H. T.According to numerous studies, airborne nanoparticles have a potential to produce serious adverse human health effects when deposited into the respiratory tract. The most important parts of the lung are the alveolar regions with their enormous surface areas and potential to transfer nanoparticles into the blood stream. These effects may be potentiated in case of the elderly, since this population is more susceptible to air pollutants in general and more to nanoparticles than larger particles. The main goal of this investigation was to determine the exposure of institutionalized elders to nanoparticles using Nanoparticle Surface Area Monitor (NSAM) equipment to calculate the deposited surface area (DSA) of nanoparticles into elderly lungs. In total, 193 institutionalized individuals over 65 yr of age were examined in four elderly care centers (ECC). The occupancy daily pattern was achieved by applying a questionnaire, and it was concluded that these subjects spent most of their time indoors, including the bedroom and living room, the indoor microenvironments with higher prevalence of elderly occupancy. The deposited surface area ranged from 10 to 46 mu m(2)/cm(3). The living rooms presented significantly higher levels compared with bedrooms. Comparing PM10 concentrations with nanoparticles deposited surface area in elderly lungs, it is conceivable that living rooms presented the highest concentration of PM10 and were similar to the highest average DSA. The temporal distribution of DSA was also assessed. While data showed a quantitative fluctuation in values in bedrooms, high peaks were detected in living rooms.