MEASUREMENT OF AEROSOLS IN ENGINEERED NANOMATERIALS FACTORIES FOR RISK ASSESSMENT

In relation to potential health risks, there is little available information on exposure to aerosols containing nanometer-size particles in work environments in factories producing engineered nanomaterials. We measured the concentrations and size distributions of particles of nanometer-sized to coarse-sized particles in an engineered carbon nanomaterial factory and a titanium dioxide factory. In addition, particles were collected with a quartz fiber filter in the engineered carbon nanomaterial factory, and their morphology was examined by scanning electron microscopy and their carbon composition was examined with a carbon analyzer. In the carbon nanomaterial factory, the particle number increased to more than 10⁵ cm^-3 when a vacuum cleaner was used to clean the inside of the producing device, and the particle number increased for particles with a diameter of about 100 nm compared with the background. This is the only case an increase in particle numbers is observed during this measurement. The emitted particles appear to consist of agglomerates of carbon nanomaterial particles smaller than 100 nm. The major fraction was the EC3 fraction (EC: elemental carbon; combustion at 800°C in a 98:2 He/O₂ atmosphere), which is a minor fraction in diesel engine particulate matter. This suggests that the combustion temperature can be used to differentiate atmospheric particulate matter from engineered carbon material. Personal sampling conducted in addition to stationary measurements in the titanium dioxide factory indicated that stationary measurements can be used to generate representative data on the basis of the particle number but not the particle mass.