Schneider T, Jensen KA. Relevance of aerosol dynamics and dustiness for personal exposure to manufactured nanoparticles. Journal of Nanoparticle Research 2009;11(7):1637-50.
Production and handling of manufactured nanoparticles (MNP) may result in
unwanted worker exposure. The size distribution and structure of MNP in the
breathing zone of workers will differ from the primary MNP produced.
Homogeneous coagulation, scavenging by background aerosols, and surface
deposition losses are determinants of this change during transport from
source to the breathing zone, and to a degree depending on the relative
time scale of these processes. Modeling and experimental studies suggest
that in MNP production scenarios, workers are most likely exposed to MNP
agglomerates or MNP attached to other particles. Surfaces can become
contaminated by MNP, which constitute potential secondary sources of
airborne MNP-containing particles. Dustiness testing can provide insight
into the state of agglomeration of particles released during handling of
bulk MNP powder. Test results, supported by field data, suggest that the
particles released from powder handling occur in distinct size modes and
that the smallest mode can be expected to have a geometric mean diameter
>100 nm. The dominating presence of MNP agglomerates or MNP attached to
background particles in the air during production and use of MNP implies
that size alone cannot, in general, be used to demonstrate presence or
absence of MNP in the breathing zone of workers. The entire respirable size
fraction should be assessed for risk from inhalation exposure to MNP.