Measurement and Monitoring Strategy for Assessing Workplace Exposure to Airborne Nanomaterials - Safety of Nanomaterials along Their Lifecycle - page 241

worker exposure. In this case, the operator of the facility will need to take additional
risk management measures to mitigate exposure (see Figure 11.1). This may include
closing leaks, adding an enclosure to the facility, or improving the local ventilation.
The effectiveness of such measures will need to be verified by tier 2 measurements.
11.3 CONCLUSIONS
The tiered approach described above presents a pragmatic approach to assess expo-
sure in workplaces, which is also feasible for small and medium enterprises. While
in the past, most exposure related measurements for nanomaterials were quite cost
and labor intensive, the possibility of doing a simplified screening or monitoring first
simplifies the whole process. Now, such intensive measurements are only required if
the screening revealed significantly increased concentrations. At the same time the
approach and the corresponding SOPs for the first time suggested clear data evalua-
tion procedures and clear decision criteria whether or not a measured particle concen-
tration in the workplace is significantly increased. The approach therefore provides
a first step towards a more harmonized and eventually standardized nanomaterial
exposure assessment. The approach and SOPs have been widely distributed and are
currently discussed within the framework of international harmonization activities.
It should, however, be noted that the presented tiered approach also has some limita-
tions. Strictly, it is more focused on the release of nanomaterials from processes rather
than the exposure itself. The assessment of exposure requires the use of personal sam-
plers or monitors, taking samples in the breathing zone of a worker, that is, within
a 30-cm hemisphere around mouth and nose. For assessing exposure to nanomateri-
als, such instruments have only very recently become available and are hence not yet
included here. Furthermore, the approach is only usable for materials that have been
shown to be not highly toxic. In the case of toxic materials, small amounts of such
substances in the workplace air may have dramatic effects. If these amounts are within
the typical fluctuations of the particle concentrations in the workplace, they cannot be
detected with the means described earlier. In such a case a measurement technique that
specifically detects the toxic material would need to be employed, similar to a gas alarm
sensor. Since as of now there are no such online measurement techniques, only the use
of particle sampling and subsequent offline analyses, as foreseen in tier 3 can be used.
ACKNOWLEDGMENTS
This research was conducted under the umbrella of the nanoGEM project, funded
by the German Ministry for Education and Research (BMBF) under grant number
03X0105. The financial support is gratefully acknowledged.
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