1 Contributions 1 . 1 Primary Particles – Agglomerates – Aggregates

The existence of nanosized particles at the workplace is not a new phenomenon . As early as in 1997, the Deutsche Forschungsgemeinschaft, Commission for the investigation of Health Hazards of chemical compounds in the work area, defined the term “ultrafine particles” in its List of Maximale ArbeitsplatzKonzentration (MAK) and Biologischer Arbeitsstoff-Toleranzwert (BAT) Values . The definition of “ultrafine particles” as it relates to the workplace corresponds primarily to the term nanoparticles as it is currently being used in research and technology . Nanoparticles are not a new discovery of science, nor are they an innovation, as regards their definition based on their particle size or as a technical achievement. They have, however, always been components of smoke. Their use as natural iron oxide and carbon black particles has already been applied in prehistoric cave paintings, such as in Altamira, etc. Nanosized particles differ from coarser particles by their increasing tendency to form agglomerates . Such agglomerates are macroscopically perceived as one particle and may break down into their primary particles in biological material; this dissociation is of toxicological relevance (Oberdörster et al. 2005).