Workplace atmospheres - Characterization of ultrafine aerosols/ nanoaerosols - Determination of the size distribution and number concentration using differential electrical mobility analysing systems

Within occupational hygiene, aerosol concentrations are usually measured in terms of mass concentrations. For ultrafine aerosols and nanoaerosols, the molecules on the particle surfaces, compared with the molecules inside the particles, shall be considered to have a higher significance with which the traditional measuring procedures cannot comply with. Due to this, other exposure metrics such as the number and surface area concentration are becoming more important for predicting health effects of certain aerosols, depending on chemical and physical properties. This standard provides a guideline for the determination of the number concentration and size distribution of ultrafine aerosols and nanoaerosols at workplaces by using mobility particle sizers (also called differential mobility analysers). The method can be used by occupational hygienists and researchers to effectively characterize and assess workplace exposure to ultrafine aerosols and nanoaerosols. Specifically, the differential mobility analysing system (DMAS), now available from several vendors, is discussed. Principles of operation, problems of sampling in the workplace environment, calibration, equipment maintenance, measurement uncertainty, and reporting of measurement results are covered. The standard has been prepared under the chairmanship of CEN/TC 137 "Assessment of workplace exposure to chemical and biological agents" (secretariat: DIN), in collaboration with Technical Committee ISO/TC 146/SC 2, "Workplace atmospheres" (secretariat: ANSI, USA), in accordance with the Vienna Agreement. The responsible German Committee is Working Group NA 095-03-01-01 "Staub" ("Particulate matter") of Working Committee "Messstrategien und Anforderungen an Messverfahren" ("Measurement strategies and requirements for test methods") of NASG.