Measurement and Monitoring Strategy for Assessing Workplace Exposure to Airborne Nanomaterials - Safety of Nanomaterials along Their Lifecycle - page 233

databases, which eventually are the base for epidemiological studies. Furthermore,
especially small and medium enterprises may not have the financial means to carry
out such measurement campaigns. A pragmatic, clear, and harmonized approach is
hence required for both measurement and data evaluation.
Several groups across the globe have been working on the development of such
measurement strategies over the recent years (e.g., Methner, Hodson, and Geraci
2009a and 2009b; BAuA et al. 2011; Asbach et al. 2012b; Witschger et al. 2012, oth-
ers are still unpublished) and efforts have been taken to harmonize these approaches
(Brouwer et al. 2012). All these measurement strategies have many similarities. For
example, all the aforementioned approaches are tiered to be pragmatically applicable.
Tier by tier the measurement effort increases and the uncertainty hence decreases.
Clear decision criteria for moving to a higher tier are defined. One of these measure-
ment strategy frameworks was developed in the German project nanoGEM and is
described in detail here. Advanced standard operation procedures (SOPs) are freely
available for every measurement step of this approach (Asbach et al. 2012b) as well
as for the use of the various measurement instruments applied.
11.2 THE NANOGEM TIERED APPROACH
The aforementioned challenges in assessing exposure to airborne engineered nano-
materials were considered in the nanoGEM approach, particularly taking into
account that an exposure assessment strategy needs to be widely adopted, that is, in
large industry, in small and medium enterprises, and in research laboratories. The
approach therefore has to be pragmatic and also needs to offer means for a rather
simple assessment. The nanoGEM strategy is based on a publication by the German
Chemical Industry Association VCI (BAuA et al. 2011) which foresees three tiers.
The goal of tier 1 is to gather as much information as possible about the workplace
and the nanomaterial(s) considered. If a release of the nanomaterial into the work-
place air cannot be excluded, a rather simple measurement of the particle concentra-
tions in the workplace is done in tier 2. If these measurements reveal that the particle
concentration in the workplace is significantly higher than the background concen-
tration and this increase cannot be tracked back to other, not nanomaterial related
processes in the workplace, an extensive measurement campaign is carried out in
tier 3. If the result of a tier 3 measurement is that nanomaterials are released from
the process leading to worker exposure, additional risk management steps have to be
taken by the company. The overall three-tiered hierarchical structure of the concept
was maintained in the nanoGEM strategy, as shown in Figure 11.1.
11.2.1 t ier 1
The task in tier 1 is to clarify, if and how nanomaterials are used in the respective
workplace and whether there is a chance that they can be released from the cor-
responding processes. The latter usually requires an on-site inspection of the con-
sidered workplace(s). If a release cannot be excluded, the potential exposure has to
be determined in tier 2. Furthermore, the type of nanomaterials used in the process
has to be specified and information on its potential toxicity gathered. If the material