Dustiness

Dustiness is the tendency of particles to become airborne in response to a mechanical or aerodynamic stimulus. Dustiness is affected by the particle shape, size, and inherent electrostatic forces. Dustiness increases the risk of inhalation exposure.[1]

Dusty materials tend to generate aerosols with high particle concentrations measured in number or in mass. The tendency of powdered materials to release airborne particles under external energies indicates their dustiness level.[2]

The dusty level of powders directly affects worker exposure scenarios and associated health risks in occupational settings. Powder-based aerosol particles can pose adverse effects when deposited in human respiratory systems via inhalation.[3]

Motivation

A significant motivation for quantifying and measuring the dustiness of materials comes from the area of workplace safety. The potential health impacts of suspended particles, particularly by inhalation, can be significant.

Dustiness testing

The amount of dust produced during handling or processing of a powder can be affected by the nature of the handling process, the ambient humidity, the particle size and water content of the powder, and other factors. To measure dustiness of a particular powder in a replicable way, standardized testing procedures have been created and published.[2]

European Committee for Standardization - Continuous Drop and Rotating Drum

Various laboratory systems have been developed to test dustiness of fine powders. A European standard on dustiness testing has been established by the European Committee for Standardization (CEN) since April 2006.[4] This standard is especially related to human exposure in workplace (EN 15051). It describes two methods: the rotating drum system and continuous drop system, both of which use gravity to stimulate the material and generate aerosols.[5][2] The rotating drum method involves placing the powder in a cylinder containing baffles, while the continuous drop system involves allowing a stream of powder to fall onto a surface. While the drum approach has been successfully scaled down by some researchers, published standards call for tens or hundreds of grams of material, a stipulation that can prove problematic for nanomaterials, pharmaceuticals and other expensive powders.[2]

Aerosol generation system

Recently, an aerosol generation system based on laboratory funnel (resembling a fluidized bed) has been developed, which has the potential to become an alternative or supplementary method to the existing systems in dustiness testing.[6][7] Its performance was compared to other three aerosolization systems using the same test materials.[8][9]

Nanomaterials dustiness

The dustiness of the nanomaterials can influence potential exposures and the selection of the appropriate engineering control during the manufacturing production.[1] Electrostatic forces influence the stability of particle dispersion in air and effect the dustiness.[1] Nanomaterials in dry powder form tend to pose the greatest risk for inhalation exposure, while nanomaterials suspended in a liquid typically present less risk via inhalation.[1]

Safety measures

The full life cycle of a nanomaterial should be considered when planning to control for dust exposure. Nanomaterial synthesis reactors, nanoparticle collection and handling, product fabrication with nanomaterials, product use, and product disposal are potential sources of dust exposure.[1]

National Institute for Occupational Safety and Health recommends the use of high-efficiency particulate air (HEPA) filters on local exhaust ventilation, laboratory chemical hoods, lowflow enclosures, and any other containment enclosures as a best practice during the handling of engineered nanomaterials.[1]

References
  1. "General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories". National Institute for Occupational Safety and Health. May 2012. pp. 5–10. doi:10.26616/NIOSHPUB2012147. Retrieved 2016-07-15.
  2. Evans, Douglas E.; Turkevich, Leonid A.; Roettgers, Cynthia T.; Deye, Gregory J.; Baron, Paul A. (2013-03-01). "Dustiness of Fine and Nanoscale Powders". The Annals of Occupational Hygiene. 57 (2): 261–277. doi:10.1093/annhyg/mes060. ISSN 0003-4878. PMC 3750099. PMID 23065675.
  3. Theodore F. Hatch; Paul Gross; George D. Clayton. Pulmonary Deposition and Retention of Inhaled Aerosols. ISBN 978-1-4832-5671-9.
  4. LIDÉN, GÖRAN (2006). "Dustiness Testing of Materials Handled at Workplaces". Ann Occup Hyg. 50 (5): 437–439. doi:10.1093/annhyg/mel042. PMID 16849593.
  5. Schneider T.; Jensen KA (2008). "Combined single-drop and rotating drum dustiness test of fine to nanosize powders using a small drum". Ann Occup Hyg. 52 (1): 23–34. doi:10.1093/annhyg/mem059. PMID 18056087.
  6. Yaobo Ding; Michael Riediker (2015). "A system to assess the stability of airborne nanoparticle agglomerates under aerodynamic shear". Journal of Aerosol Science. 88: 98–108. Bibcode:2015JAerS..88...98D. doi:10.1016/j.jaerosci.2015.06.001.
  7. Yaobo Ding; Michael Riediker (2016). "A System to Create Stable Nanoparticle Aerosols from Nanopowders". Journal of Visualized Experiments. 113 (113): e54414. doi:10.3791/54414. PMC 5091692. PMID 27501179.
  8. Yaobo Ding; Burkhard Stahlmecke; Araceli Sánchez Jiménez; Ilse L. Tuinman; Heinz Kaminski; Thomas A. J. Kuhlbusch; Martie van Tongeren; Michael Riediker (2015). "Dustiness and Deagglomeration Testing: Interlaboratory Comparison of Systems for Nanoparticle Powders". Aerosol Science and Technology. 49 (12): 1222–1231. Bibcode:2015AerST..49.1222D. doi:10.1080/02786826.2015.1114999. S2CID 53998736.
  9. Yaobo Ding; Burkhard Stahlmecke; Heinz Kaminski; Yunhong Jiang; Thomas A. J. Kuhlbusch; Michael Riediker (2016). "Deagglomeration testing of airborne nanoparticle agglomerates—stability analysis under varied aerodynamic shear and relative humidity conditions". Aerosol Science and Technology. 50 (11): 1253–1263. Bibcode:2016AerST..50.1253D. doi:10.1080/02786826.2016.1216072.
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