Biomedical Engineering Reference
In-Depth Information
et al. (2001) found that the particle number concentration was a more appropriate metric for lung
disease. Several toxicological studies have indicated that there is a better dose-response relationship
while using ultrafine and fine particle surface areas as exposure metrics (Oberdörster, 2000; Trans
et al., 2000; Brown et al., 2002). Therefore, the change in exposure metrics for nanoparticles from
a mass basis to both alternative metrics of particle number and surface area concentrations have
been proposed (Kreyling et al., 2006; Maynard and Aitken, 2007). However, at this moment, no
scientific consensus can be referred to for the selection of an appropriate exposure metric (Maynard
and Aitken, 2007; Paik et al., 2008). Therefore, a multimetric exposure assessment appears to be
reasonable, given the present situation.
2.3.2 M
easureMeNt
I
NstruMeNts
In principle, the sampling equipment for assessing occupational exposures should be personal, or at
least portable, from an easy-to-use point of view. In addition, the instrument should also be battery-
powered, robust, and relatively inexpensive in order to lower the cost. There are various devices
that can be used to measure the mass, surface area, or the number concentrations of particles in
workplaces. However, it should also be noted that not any developed instrument could be used
for simultaneously measuring the nanoparticle exposures of the above metrics. Since no health-
related sampling convention has been established for nanoparticles, the developed device could be
used for the specific aims that have been set for the given study. Table 2.1 shows a summary of the
sampling devices used in workplaces for nanoparticle exposure and assessment studies (ISO, 2007;
Kuhlbusch et al., 2011; CJ Tsai et al., 2012). A detailed description of instruments is presented in
the following subsections.
TABLE 2.1
Instruments and Techniques for Monitoring Nanoparticle Exposures
Metrics
Devices
Sampling Types
Size Range
Remarks
Mass
Personal
nanoparticle
sampler (PENS)
Time-integrated
Collection of both mass concentrations of
respirable particles and nanoparticles
simultaneously
<100 nm
and >4 μm
Nano-MOUDI
Time-integrated
0.01-18 μm
Particle size distribution by mass, chemical, and
morphology identification
Low-pressure
cascade
impactor
Time-integrated
Particle size distribution by mass, chemical and
morphology identification
>20 nm
Number
CPC
Time-resolved
0.01-1 μm
Real-time number concentration
SMPS
Time-resolved
2.5-1000 nm
Real-time size-selective (mobility diameter)
detection of number concentration
ELPI
Time-resolved
Real-time size-selective (aerodynamic diameter)
detection of active surface area concentration.
Size-selected samples may be further analyzed
off-line
6 nm-10 μm
FMPS
Time-resolved
5.6-560 nm
Same as SMPS
P-Trake
Time-resolved
Same as CPC
0.02-1 μm
Surface area
NSAM
Time-resolved
Deposited surface area concentration of TB and
AL regions
0.01-1 μm
EAD/MEAD
Time-resolved
0.01-1 μm
Aerosol length (EAD), lung-deposited surface
area (MEAD) of H, TB, and AL regions
AeroTrak 9000
Time-resolved
0.01-1 μm
Same as NASM
LQ1-DC
Time-resolved
0.01-1 μm
Active surface area
