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Characterization of exposures to airborne nanoscale particles during friction stir welding of aluminum.

Authors
Pfefferkorn-FE; Bello-D; Haddad-G; Park-JY; Powell-M; Mccarthy-J; Bunker-KL; Fehrenbacher-A; Jeon-Y; Virji-MA; Gruetzmacher-G; Hoover-MD
Source
Ann Occup Hyg 2010 Jul; 54(5):486-503
NIOSHTIC No.
20037324
Abstract
Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 microm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 microm) with 1-s resolution, lung deposited surface areas, and PM2.5 concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 microm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at 30 and 550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at 4.0 x 105 particles cm-3, whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm-3, depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10-100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) microg m-3; the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial operations.
Keywords
Particulate-dust; Particulates; Metal-dusts; Metal-finishing; Metallic-compounds; Metallic-dusts; Metals; Iron-compounds; Zinc-compounds; Aluminum-compounds; Breathing-atmospheres; Respirable-dust; Dust-exposure; Dust-inhalation; Dust-particles; Aerosol-particles; Nanotechnology; Author Keywords: aluminum; friction stir welding; nanoparticle exposures; occupational safety and health; size distribution; zinc
Contact
Dhimiter Bello, Department of Work Environment, University of Massachusetts Lowell, Lowell, MA 01854, USA
CODEN
AOHYA3
CAS No.
7429-90-5; 7439-89-6; 7440-66-6
Publication Date
20100701
Document Type
Journal Article
Email Address
dhimiter_bello@uml.edu
Funding Type
Grant
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-T01-OH-008424
Issue of Publication
5
ISSN
0003-4878
NIOSH Division
DRDS
Priority Area
Healthcare and Social Assistance
Source Name
Annals of Occupational Hygiene
State
WV; WI; MA; MN; PA
Performing Organization
University of Massachusetts - Lowell
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