Overview
ISO/TS 21361:2025 is a technical specification in nanotechnologies that defines a validated method to quantify and identify air concentrations (#/cm³) of carbon black and amorphous silica in the nanoparticle size range within mixed-dust manufacturing environments. The method is based on air sampling with an electrical low pressure cascade impactor (ELPCI) and off-line particle identification using transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). It applies where particle types are chemically and physically distinct or where confounders (e.g., diesel aerosols) can be controlled.
Key topics and requirements
- Sampling equipment: Use of an ELPCI with stage cut-offs spanning roughly 6 nm to 10 µm to produce size-resolved particle counts (aerodynamic diameter basis).
- Analytical workflow: Combine ELPCI size-distribution counts with TEM–EDS (or optionally SEM–EDS) identification of particles collected on impactor stages.
- Quantification approach: Calculate material-specific concentration by multiplying total particle count in a size bin by the fraction of particles identified as carbon black or amorphous silica from TEM–EDS analysis.
- Instrument and lab requirements: TEM, EDS instrumentation and suitable substrates/grids; procedures for substrate preparation, instrument conditions, data collection and uncertainty assessment are specified.
- Performance and limitations: Addresses limits of detection, particle counting uncertainty, and TEM/EDS analysis uncertainty. Method is more sensitive than many mass-based techniques but is labor intensive and intended as a higher-tier exposure assessment tool.
- Applicability constraints: Intended for industrial manufacturing environments with mixed dusts where material types can be distinguished or confounders controlled.
Applications
- Occupational exposure assessment for workers in industries using carbon black or amorphous silica (e.g., rubber, coatings, insulation).
- Exposure characterization in process hot spots identified by screening methods (real-time monitors).
- Research and development where size-resolved, material-specific nanoparticle concentrations are required to inform health risk comparisons and PPE selection.
- Regulatory and standards alignment when developing nano-specific occupational exposure limits or validating control strategies.
Who should use this standard
- Industrial hygienists and occupational safety professionals conducting advanced nanoparticle exposure assessments.
- Analytical laboratories performing TEM–EDS characterization of airborne nanoparticles.
- Employers and consultants in manufacturing sectors using carbon black and amorphous silica.
- Researchers developing nano-specific exposure metrics or controls.
Related standards
Keywords: ISO/TS 21361:2025, nanotechnologies, ELPCI, TEM, EDS, carbon black, amorphous silica, nanoparticle air concentration, mixed dust manufacturing, occupational exposure.