Protecting employees’ health

Technical precautions such as filters, extractors and protective clothing and equipment are taken as necessary to ensure suitable protection in the workplace. Regular measurement of particulates in the workplace and medical check-ups ensure that these measures are effective.

Safety precautions for research

In the labs and pilot plants in which Evonik uses carbon nanotubes, for example, as part of its contribution to the INNO.CNT alliance, there are standard operating procedures for handling CNTs and staff receive special trained. The precautions include mandatory wearing of disposable protective suits, dust masks and special gloves.

In view of its long-standing experience, Evonik assumes that employees working on the production of fine-particle substances and handling such products are not exposed to health risks, providing they observe the applicable safety standards. This assessment is based on measurements and scientific studies.

Measuring exposure in the workplace

Workplace measurements

Evonik regularly measures the concentration of fine particulates in the air in its production facilities. The overall concentration of alveolar dust (particles that can be breathed into the lungs) in normal production of fumed oxides and carbon blacks is well below the exposure limit (German Technical Rules on Dangerous Substances 900). In addition, Evonik measures particulate concentrations and particle size distribution in workplaces where CNTs are used to produce masterbatches. The results do not indicate any additional exposure resulting from the release of CNTs during such work.

Measurement of particles in the range below 100 nm comprises measuring the number of particles in a specific unit of volume, in this case particles per cm3. Various appliances are available to take such measurements. Condensation particle counters (CPC) measure particle sizes from 10-1,000 nm, while the scanning mobility particle sizer (SMPS) measures particles of 10 to 350 nm. The SMPS also classifies particles, thus mapping the particle size distribution in the area measured.

First measurements of exposure to ultra-fine particulates

The first ever measurement of exposure to particulates in the nanometer range was carried out by the carbon black industry in 2000 with support from the International Carbon Black Association (ICBA). The results of this first survey on exposure to ultra-fine particulates in carbon black facilities were published in 2004. Ultra-fine particulates measure less than 100 nanometers. The term ultra-fine particle is used as a synonym for nanoparticles. The investigation did not show any additional exposure in the workplace resulting from the entrainment of carbon black particulates. The study, which was commissioned by the International Carbon Black Association (ICBA) was carried out by Professor Heinz Fissan in three carbon black production facilities, including one of Evonik’s facilities. The ICBA’s members are leading producers of carbon blacks.

Further exposure measurements taken by Evonik and as part of the NanoCare project show that in normal operation, the concentration of particulates measuring less than 100 nm in the workplace is comparable to the concentration in the ambient air. Such products thus do not cause additional exposure to nanoparticles in the workplace.