Scientific publications

Scientific publications

Using the Aerasense NanoTracer for simultaneously obtaining several ultrafine particle exposure metrics

J. Marra

Abstract

The expanding production and use of nanomaterials increases the chance of human exposure to engineered nanoparticles (NP), also referred to as ultrafine particles (UFP; ≤ 100 – 300 nm). This is particularly true in workplaces where they can become airborne and thereafter inhaled by workers during nanopowder processing. Considering the suspected hazard of many engineered UFPs, the general recommendation is to take measures for minimizing personal exposure while monitoring the UFP pollution for assessment and control purposes. The portable Aerasense NanoTracer accomplishes this UFP monitoring, either intermittently or in real time. This paper reviews its design and operational characteristics and elaborates on a number of application extensions and constraints. The NanoTracer’s output signals enable several UFP exposure metrics to be simultaneously inferred. These include the airborne UFP number concentration and the number-averaged particle size, serving as characteristics of the pertaining UFP pollution. When non-hygroscopic particles are involved, the NanoTracer’s output signals also allow an estimation of the lung-deposited UFP surface area concentration and the lung-deposited UFP mass concentration. It is thereby possible to distinguish between UFP depositions in the alveolar region, the trachea-bronchial region and the head airway region, respectively, by making use of the ICRP particle deposition model.

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Paper 

Presentation at Nanosafe 2010

Published in:   Journal of Physics: Conference Series (JPCS)

 

Monitor for detecting and assessing exposure to airborne nanoparticles

J. Marra et al

Abstract

An important safety aspect of the workplace environment concerns the severity of its air pollution with nanoparticles (NP; < 100 nm) and ultrafine particles (UFP; < 300 nm). Depending on their size and chemical nature, exposure to these particles through inhalation can be hazardous because of their intrinsic ability to deposit in the deep lung regions and the possibility to subsequently pass into the blood stream. Recommended safety measures in the nanomaterials industry are pragmatic, aiming at exposure minimization in general, and advocating continuous control by monitoring both the workplace air pollution level and the personal exposure to airborne NPs. This paper describes the design and operation of the Aerasense NP monitor that enables intelligence gathering in particular with respect to airborne particles in the 10–300 nm size range. The NP monitor provides real time information about their number concentration, average size, and surface areas per unit volume of inhaled air that deposit in the various compartments of the respiratory tract. The monitor’s functionality relies on electrical charging of airborne particles and subsequent measurements of the total particle charge concentration under various conditions. Information obtained with the NP monitor in a typical workplace environment has been compared with simultaneously recorded data from a Scanning Mobility Particle Sizer (SMPS) capable of measuring the particle size distribution in the 11 – 1086 nm size range. When the toxicological properties of the engineered and/or released particles in the workplace are known, personal exposure monitoring allows a risk assessment to be made for a worker during each workday when the workplace-produced particles can be distinguished from other (ambient) particles.

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Paper 

Presentation at Nanosafe 2008

Published in:   Journal of Nanoparticle research (Springer) 

 

Nanoparticle Monitoring for Exposure Assessment

Monitoring airborne nanoparticles creates awareness and enables control

J. Marra et al

Abstract

...When the hazard of a certain engineered nanoparticle is unknown, precautionary measures aiming at exposure minimization are recommended in workplaces wherein nanoparticles are handled or processed. In parallel, a continuous control of the ambient air nanoparticle pollution level is advocated,preferably by monitoring both the workplace nanoparticle pollution level and the cumulative personal exposure to airborne nanoparticles. This calls for the use of an nanoparticle monitor capable of yielding an output signal, which is proportional to a metric that is relevant for assessing both the nanoparticle and the ambient UFP exposure levels and the relative health risk associated with those exposures. The Aerasense nanoparticle monitor, discussed in this article, is capable of doing just that in a unique way that cannot be accomplished with the existing commercial equipment. Its functionality accounts for the deposition pattern of airborne particles in the respiratory tract and their subsequent behavior,while being embodied such as to satisfy practical demands concerning the portability, cost, and robustness of a nanoparticle monitor.
In what follows, the deposition behavior of inhaled nanoparticles in the respiratory tract will be discussed in more detail, followed by an explanation of the design and operation of the Aerasense nanoparticle monitor. Its response in a number of relevant environments wherein the air is polluted to various degrees with nanoparticles or UFPs will be illustrated,thereby highlighting the application scope of the Aerasense nanoparticle monitor both indoors and outdoors.

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Published in:   IEEE Nanotechnology magazine 


About comparative measurements between a Philips Aerasense NanoTracer, Philips Research Europe,and a Scanning Mobility Particle Sizer, TSI Inc.  

Summary

The experiments show very promising preliminary results with respect to the determina-tion of particle number concentrations when ultrafine combustion aerosols like diesel particulate matter are concerned. The direct reading measurement of number concentra-tions where these types of aerosols are the dominant aerosol constituents does not seem to be a problem with the Philips Aerasense NanoTracer device. Correlations with R2 > 0.99 with respect to the currently mainly used instrument for the detailed measure-ment of particle number concentration distributions are quite satisfactory....

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