Suchergebnisse

The use of real-time measurement techniques for objectifying occupational exposure situations is rapidly expanding. However, in many cases, the calibration data provided by manufacturers must be completed by aerosols representative of those present in occupational environments. Present on the market for about ten years, the DiSCmini device is one of the few devices that measures personal exposure to nanometer sized aerosols in real time. Laboratory work conducted on 13 devices provided knowledge about their metrological performance. The experimental data, established for a large range of test aerosols, indicate that this instrument tends to overestimate concentration by 30 to 100 %, and underestimate particle diameter by 20 to 30 %.

The use of the DiSCmini has developed considerably in the context of evaluating inhalation exposure to nanoparticles. This article presents the results obtained during measurement campaigns at workplaces. A few examples describe the applicability of the DiSCmini to measure nano-objects in different metrics complementary to standard exposure measurement methods.

This article is the follow up of the instrument's working principle description and laboratory comparison [1], that showed its ability to determine personal exposure to ultrafine particles and nano-objects in the size range below approximately 700 nm. Besides the number concentration, also the surface area concentration as well as a mean diameter of the aerosol is determined. The DiSCmini is one of the few instruments allowing person mounted use to measure directly the personal exposure to ultrafine particles. For a more comprehensive exposure determination, other instruments can be useful like direct reading instruments for the size range above 700nm, in addition to conventional aerosol samplers for mass concentrations. Although occupational exposure limit values for a number concentration are not in use for ultrafine particles or nano-objects, number based reference values can be chosen for an assessment of the exposure [2]. Such easy to use instruments like the DiSCmini can also be used in a tiered approach for exposure determination of nano-objects as described in a European Standard [3]. The first two phases of the latter approach is a suitable application to get an overview of the concentrations. Another application for such direct reading instruments will be the assessment of protective measures at particle emitting processes, e.g. the application of local exhaust ventilation [4]. Further experience in using the DiSCmini in the laboratory and the field was described in [5, 6, 7], while a review on exposure measurement methods for nano-objects is given in [8]. The following part describes examples of use of the DiSCmini and should help the reader to plan such applications and show which data can be expected.