The Identification of Exposure Metrics for Use in Evaluation of Inhalation Exposure to Nano‑Objects and their Aggregates and Agglomerates (NOAA) in the Workplace

This report provides a comprehensive review of methods for assessing inhalation exposure to nano-objects and their aggregates/agglomerates (NOAA) in workplace environments. It highlights the limitations of traditional mass-based metrics and recommends a multi-metric approach, such as particle number concentration, surface area and lung-deposited surface area, to improve correlation with toxicological effects. The document compares real-time instruments and offline analyses, and emphasises personal sampling for accurate exposure characterisation. Its tiered framework, from screening to detailed investigations, offers practical guidance for industry and regulators. This contribution supports occupational safety strategies by aligning measurement practices with the specific properties of nanoscale materials.