A proposal of method for evaluating airborne MWCNT concentration.
As multi-wall carbon nanotubes (MWCNTs) come to be used in a wider range of products, increasing production is expected to result in greater exposure of workers to MWCNTs. In this research, we present a method for evaluating the concentration of MWCNT aerosols distinctively on the basis of the elemental carbon (EC) concentration. Respirable dust is sampled using a Sioutas cascade impactor (SCI) for a certain volume of workplace air. The SCI can collect size-segregated particles having aerodynamic diameters of 2.5 μm, 1.0 μm, 0.5 μm, 0.25 μm and <0.25 μm. MWCNTs in sampled particles are determined by carbon analysis. Based on the phenomenon that MWCNTs easily aggregate/agglomerate, the present procedure for distinguishing MWCNTs uses the EC in particles larger than 1 μm as an index of MWCNT; the EC is oxidized at a high temperature, 920°C, in carbon analysis. We propose a three-step procedure for distinguishing between MWCNT aerosol and atmospheric particulate matter, and for measuring MWCNT concentrations in workplace air on the basis of EC concentration.
Work Environment Research Group, National Institute of Occupational Safety and Health, Kawasaki, Japan. ono@h.jniosh.go.jp
Mariko
M
Ono-Ogasawara
Toshihiko
T
Myojo
D000395:Air Pollutants, Occupational / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D007564:Japan; D037742:Nanotubes, Carbon / Q000032:analysis*; D016273:Occupational Exposure / Q000032:analysis
D000395:Air Pollutants, Occupational; D037742:Nanotubes, Carbon