Environmental Engineering Reference
In-Depth Information
A new instrument on the market, the Nanoparticle Surface Area Monitor (TSI 3550,
Nanoparticle Surface Area Monitor, 2005), is used for assessment of deposited surface area
(DSA) in the lung. Lung deposition estimates from this instrument are based on correlations
developed (Wilson et al., 2004) between the electrical signal and modeled DSA. The instrument
is said to be capable of detecting particles with diameters down to 10 nm.
One of the important problems in the safety of people working with nanomaterials is the efi-
ciency of respirators, discussed in many reports: (Strategic Plan for NIOSH).
16.1.5 n
anoParticle
r
esPirators
t
rue
e
FFiciency
M
easureMents
The problem of respirator eficiency is discussed in many reports: Nanotechnology (2005), Aitken
et al. (2004), White Paper on Nanotechnology, IRGC, Orwin Renn and Mike Roco Geneva,
Switzerland, Shaffer (2008). It is well known that the determining factor which governs the effec-
tiveness of respiratory protective equipment (RPE) is not absolute penetration through the ilter, but
rather face-seal leakage, which bypasses the device.
In Ruzer et al. (1995) the new idea for measuring the true eficiency of respirators was used.
Let us denote the terms as follows:
A
0
—measured gamma-activity in the lung of miners before entering radon atmosphere
(background measurement).
A
1
- A
0
—measured gamma-activity in the lung of miners without wearing respirator
A - A
0
—measured gamma-activity in the lung of miners with respirator
Then respirator eficiency will be (A - A
0
)/(A
1
- A
0
) 100%
Penetration coeficient {1 - [(A - A
0
)/(A
1
- A
0
)]} 100%
Our measurements in the mines demonstrated that true respirator eficiency varies from 67% to 95%
depending on individual training, duration, and type of work.
At the present time the data on the true eficiency of respirators, including the face-leakage
problem, are unavailable.
As discussed in Geraci, NIOSH (2009), in terms of nanoparticles we still do not know nature
and extent of hazard, nature and extent of exposure, nature and extent of risk, what measure to use,
limitation of controls, limitations of protection, and what limits are appropriate. There are no spe-
ciic exposure limits.
According to Friends of the Earth (2009) there is
no consistent nomenclature, terminology and measurement standards to chacterise and describe
nanoparticles and exposure. Inadequate understanding of nanotoxicity, in particular to determine
whether acceptable exposure limits exist. No effective methods to measure and assess workplace
exposure to nanoparticles; no data on existing or predicted workplace exposure. No effective control
methods to protect workers from exposure.
Despite the hundreds of products containing nanomaterials that are already being manufactured
commercially, and the emerging body of scientiic literature demonstrating the serious risk associated
with nanotoxicity, there are still no laws to manage workplace exposure and to ensure workers' safety.
This suggested that governments have learnt little from their experiences with asbestos.
16.1.5.1
Conclusions
1. Until now it is very dificult to ind studies on measurement of nanoaerosol concentra-
tion and correspondingly exposure, especially on surface area concentration in working
conditions.
2. There is a lack of experimental data on the assessment of exposure in occupational settings.
3. In the majority of studies even on animals still the mass concentration, not a surface area,
in contradiction to new scientiic data is used as a measure of dose.
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