The Measurement
The AEROTRAK 9000 monitor does not measure the total active surface area (i.e., Fuch’s surface area) of particles suspended in air. It indicates the surface area of the fraction of these particles thatdeposit in either the tracheobronchial or alveolar regions of the human respiratory tract.

Nanoparticle Exposure
Recent research (Oberd?rster, 2001) has shown that surface area plays an important role in the toxicity of nanoparticles and is the measurement metric that best correlates with particle-induced adverse health effects. The potential for adverse
health effects is directly proportional to particle surface area (Driscoll 1996; Oberd?rster 2001).

Lung Deposition
Inhalation is the most common route of exposure for aerosols. In industrial hygiene sampling, it is common to sample aerosols according to where they deposit in the lung. Inhalable, thoracic, and respirable size fractions are common examples of size-selective sampling currently done for mass-based exposure sampling.

For nanoparticle aerosols it is important to understand how and where they deposit in the lung. Comprehensive lung deposition models are well developed for a reference worker for use in industrial hygiene exposure assessment applications. Model results show that deposition rates differ for varying particle sizes in different areas of the lung. Exposure to inhaled particles by our body is determined by where they deposit in the respiratory tract.

Applications
The AEROTRAK 9000 monitor provides a simple
and fast solution for indicating the surface area
equivalent dose of particles in the size range of 10
to 1000 nanometers. The AEROTRAK 9000 is well
suited for the following applications:
Monitoring workplace exposure to nanoparticles
  Industrial hygiene surveys
  Ambient work area monitoring
  Baseline screening and trending
  Engineering studies
Material science and production processmonitoring
Inhalation toxicology research studies
Epidemiology research studies