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Dustiness of fine and nanoscale powders.

Evans DE, Turkevich LA, Roettgers CT, Deye GJ, Baron PA - Ann Occup Hyg (2012)

Bottom Line: For many powders, a significant respirable dustiness was observed.Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size.It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Occupational Safety and Health, Chemical Exposure and Monitoring Branch, Division of Applied Research and Technology, 4676 Columbia Parkway, MS-R7, Cincinnati, OH 45226, USA. dje3@cdc.gov

ABSTRACT
Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3-37.9% and 0.1-31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300 nm to several micrometers, but no modes below 100 nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace.

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(a) Relationship between total dustiness Dtot and BET specific surface area. (b) Relationship between respirable dustiness Dresp and BET specific surface area.
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Figure 5: (a) Relationship between total dustiness Dtot and BET specific surface area. (b) Relationship between respirable dustiness Dresp and BET specific surface area.

Mentions: Relationship with BET Surface Area and Primary Particle Size. The dustiness values do not appear to be correlated with primary particle size. Primary particle size is directly related to the specific surface area provided by BET analysis (Hinds, 1999). Values for BET-derived specific surface area are provided in Table 1 for each test material. Fig. 5 displays (i) the total dustiness and (ii) the respirable dustiness, as a function of BET specific surface area. Attempts to fit to power laws resulted in the following:


Dustiness of fine and nanoscale powders.

Evans DE, Turkevich LA, Roettgers CT, Deye GJ, Baron PA - Ann Occup Hyg (2012)

(a) Relationship between total dustiness Dtot and BET specific surface area. (b) Relationship between respirable dustiness Dresp and BET specific surface area.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750099&req=5

Figure 5: (a) Relationship between total dustiness Dtot and BET specific surface area. (b) Relationship between respirable dustiness Dresp and BET specific surface area.
Mentions: Relationship with BET Surface Area and Primary Particle Size. The dustiness values do not appear to be correlated with primary particle size. Primary particle size is directly related to the specific surface area provided by BET analysis (Hinds, 1999). Values for BET-derived specific surface area are provided in Table 1 for each test material. Fig. 5 displays (i) the total dustiness and (ii) the respirable dustiness, as a function of BET specific surface area. Attempts to fit to power laws resulted in the following:

Bottom Line: For many powders, a significant respirable dustiness was observed.Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size.It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Occupational Safety and Health, Chemical Exposure and Monitoring Branch, Division of Applied Research and Technology, 4676 Columbia Parkway, MS-R7, Cincinnati, OH 45226, USA. dje3@cdc.gov

ABSTRACT
Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3-37.9% and 0.1-31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300 nm to several micrometers, but no modes below 100 nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace.

Show MeSH