Outside the wide range of potential benefits, the use of nanomaterials can endanger human health, mostly through skin contact and the risk of inhalation. This article presents the results of harmonized measurements with contextual information on the emission of nanoparticles during the manufacturing and application of nanotechnology products. The purpose of the research was to investigate the actual levels of exposure to nano-objects in real working conditions in chosen Polish companies. Measurements were carried out in various workplaces: during silver nanoparticle synthesis, production of thin nanocarbon layers, 3D-printing with the use of a nanohydroxyapatite-polymer composite and the production of special seals from thin glass foils. Research was conducted on the basis of task-based measurements and offline microscopic analysis. Realtime particle DiSCmini counters were used to determine the nano-object concentration during different processes and events: samplers for collecting air dust, and a scanning electron microscope to confirm the presence of
The dynamics of filtration efficiency and pressure drop during the simultaneous filtration of soot and oil aerosols on single-and multi-layer filters were investigated, and the determined filtration efficiency was compared with the theoretical efficiency obtained via the classical filtration theory. Additionally, the influence of liquid-phase aerosols on the morphology of the formed deposits was investigated. It was concluded that the addition of oil aerosols decreased the filtration efficiency and lowered the pressure drop increase rate for multi-layer filters.Additionally, for the filtration of aerosols containing soot and high oil concentrations, once maximum filtration efficiency was reached, an efficiency decrease occurred. The system imperfection factor was proposed as a mean to predict the efficiency of multi-layer filters. The modified version of the single fibre efficiency method was used to calculate filter mass change with reasonable accuracy.
A methodology for calculating aerosol filtration efficiency using non-woven filters with polydispersity distribution of fibre diameters was formulated. In order to verify the results of the calculations experimentally, filters made of polypropylene non-woven fabric were used to filter solid (soot) and liquid (oil) aerosols and their mixtures with different concentrations. In order to increase the accuracy of the calculations, the division of the diameter distribution into several (1-100) ranges of values was considered. The influence of the number of these intervals for theoretical and empirical equations available in the literature was investigated. This effect was found to be significant, and replacing one diameter value representing all the fibres in the filter with twenty diameter ranges, each representing only a fraction of the total fibres, is sufficient to minimize the error due to the underrepresentation of the actual fibre distribution in the filter. Calculation of the mean particle size after the filter was performed using a set of theoretical and empirical equations. The calculations take into account the change in packing density, flow velocity and fibre diameter over time as a result of filling the filter with particles deposited on it. The obtained results were compared with the measurement results. It has been found that such changes in the monofilament performance model are insufficient to properly describe the effects inside the filter.
In 2019, the European Committee for Standardization (CEN) initiated work on the preparation of a strategy for air quality monitoring at workplaces. The aim was to determine the concentrations of nano-objects and their aggregates and agglomerates (NOAA) by means of direct measurements using low-cost sensors. There is a growing need for low-cost devices that can continuously monitor the concentrations of nanoparticles, and that can be installed where nanoparticles are used or created spontaneously. In search of such a device, in this study, a smoke detector with an ionization sensor was tested. The aim of the research was to investigate the response of the analog output signal with respect to changes in environmental parameters such as the relative humidity of air. The research was conducted in controlled laboratory conditions, and the results confirmed that an ionization detector could be used to measure the concentrations of nanoaerosols. The modified smoke detector detected soot particles smaller than 100 nm. The linear regression line was calculated for the relative humidity dataset and had a slope coefficient of −1.214 × 10−4; thus, the value of the output signal was constant during the experiment. The dependence on air temperature was approximated by a second-degree curve, with a slope coefficient of −8.113 × 10−2. Air humidity affected aerosol concentrations, which may be related to surface modification of nanoparticles.
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