Comparison of Real Time Nanoparticle Monitoring Instruments in the Workplaces

Comparison of four nanoparticle monitoring instruments relevant for occupational hygiene applications

Background

The aim of this study is to make a comparison of a new small sized nanoparticle monitoring instrument, Nanoscan  SMPS, with more traditional large size instruments, known to be precise and accurate [Scanning Mobility Particle Sampler (SMPS) and Fast Mobility Particle Sizer (FMPS)], and with an older small size instrument with bulk measurements of 10-1000 nm particles (CPC3007). The comparisons are made during simulated exposure scenarios relevant to occupational hygiene studies.

Methods

Four scenarios were investigated: metal inert gas (MIG) welding, polyvinyl chloride (PVC) welding, cooking, and candle-burning. Ratios between results are compaed and Pearsson correlations analysis was performed.

Results

The highest correlation between the results is found between Nanoscan and SMPS, with Pearsson correlation coefficients above 0.9 for all scenarios. However, Nanoscan tended to overestimate the results from the SMPS; the ratio between the UFP concentrations vary between 1.44 and 2.01, and ratios of total concentrations between 1.18 and 2.33. CPC 3007 did not show comparable results with the remaining instruments.

Conclusion

Based on the results of this study, the choice of measurement equipment may be crucial when evaluating measurement results against a reference value or a limit value for nanoparticle exposure. This stresses the need for method development, standardisation, and harmonisation of particle sampling protocols before reference values are introduced. Until this is established, the SMPS instruments are the most reliable for quantification of the concentrations of UFP, but in a more practical occupational hygiene context, the Nanoscan SMPS should be further tested.

Dip coating of air purifier ceramic honeycombs with photocatalytic TiO2 nanoparticles: A case study for occupational exposure

Nanoscale TiO₂ (nTiO₂) is manufactured in high volumes and is of potential concern in occupational health. Here, we measured workers exposure levels while ceramic honeycombs were dip coated with liquid photoactive nanoparticle suspension and dried with an air blade. The measured nTiO₂ concentration levels were used to assess process specific emission rates using a convolution theorem and to calculate inhalation dose rates of deposited nTiO₂ particles. Dip coating did not result in detectable release of particles but air blade drying released fine-sized TiO₂ and nTiO₂ particles. nTiO₂ was found in pure nTiO₂ agglomerates and as individual particles deposited onto background particles. Total particle emission rates were 420×10⁹min^-1, 1.33×10⁹μm²min^-1, and 3.5mgmin^-1 respirable mass. During a continued repeated process, the average exposure level was 2.5×10⁴cm^-3, 30.3μm²cm^-3, <116μgm^-3 for particulate matter. The TiO₂ average exposure level was 4.2μgm^-3, which is well below the maximum recommended exposure limit of 300μgm^-3 for nTiO₂ proposed by the US National Institute for Occupational Safety and Health. During an 8-hour exposure, the observed concentrations would result in a lung deposited surface area of 4.3×10^-3cm²g^-1 of lung tissue and 13μg of TiO₂ to the trachea-bronchi, and alveolar regions. The dose levels were well below the one hundredth of the no observed effect level (NOEL_1/100) of 0.11cm²g^-1 for granular biodurable particles and a daily no significant risk dose level of 44μgday^-1. These emission rates can be used in a mass flow model to predict the impact of process emissions on personal and environmental exposure levels.

A System Based on the Internet of Things for Real-Time Particle Monitoring in Buildings

Occupational health can be strongly influenced by the indoor environment as people spend 90% of their time indoors. Although indoor air quality (IAQ) is not typically monitored, IAQ parameters could be in many instances very different from those defined as healthy values. Particulate matter (PM), a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air, is considered the pollutant that affects more people. The most health-damaging particles are the ≤PM₁₀ (diameter of 10 microns or less), which can penetrate and lodge deep inside the lungs, contributing to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer. This paper presents an Internet of Things (IoT) system for real-time PM monitoring named iDust. This system is based on a WEMOS D1 mini microcontroller and a PMS5003 PM sensor that incorporates scattering principle to measure the value of particles suspended in the air (PM₁₀, PM_2.5, and PM_1.0). Through a Web dashboard for data visualization and remote notifications, the building manager can plan interventions for enhanced IAQ and ambient assisted living (AAL). Compared to other solutions the iDust is based on open-source technologies, providing a total Wi-Fi system, with several advantages such as its modularity, scalability, low cost, and easy installation. The results obtained are very promising, representing a meaningful tool on the contribution to IAQ and occupational health.

Novel techniques for detection and characterization of nanomaterials based on aerosol science supporting environmental applications

The number of people exposed to nanoparticles is growing accordingly to the production and development of new nanomaterials. Moreover, this increase is expected to continue in the future. However, there is a lack of standardized sampling and metric methods to measure the level of exposure to nanoparticles, and the information related to possible adverse health effects is scarce. Aerosol technology has been detecting and characterizing nanoparticles for decades and some of their developments can be of use in nanotechnology characterization. We present here two current developments based on used principles in aerosol science, which can widen its application to the characterization of nanomaterials. On the one hand, a sample preparation technique for nanoparticle analysis by electron microscopy based on electrospray atomization technology. Several samples prepared in this way have been analysed and compared to more traditional sample preparation strategies like the "drop on grid" method. It was found that the particles deposited by electrospray generally show a much more homogeneous spatial distribution on the substrate and the number of single particles increases substantially. On the other hand, it is presented an electrical mobility classification system, DMA, with enormous possibilities for the quick and economic size characterization of suspensions of nanoparticles, thanks to its injection system by electrospray and to its high resolution in the lower range of the nanoscale. The first assessment of the abovementioned devices highlights its potential applications in exposure assessment and nanotechnological contexts.