1 Executive Summary
Scope and limitations of this study
Summary of main findings
Particle exposure and emission
Advice on particle assessment
Triggers for particle control strategies
Abbreviations
Glossary
2 Introduction
3 Overall Aim
4 Objectives
5 Scientific Literature Regarding Common Methods and Instrumentation Pertinent to the Characterisation of Airborne Engineered Nanoparticles
5.1 Properties of nanoparticles that influence measurement decisions
5.1.1 Particle size
5.1.2 The surface area and the reactivity of that surface area
5.1.3 Particle number
5.1.4 Solubility and biopersistence
5.1.5 Shape and fibres
5.1.6 Primary particle size, aggregation, and agglomeration
5.2 Measurement of nanoparticles
5.2.1 Metrics, methods, and instruments
5.2.2 Summary of some of the currently available instruments and methods for characterising particle emission and transport
5.2.2.1 Personal samplers for time resolved nanoparticle measurements
5.2.3 Response of instruments to aerosols dominated by specific particle characteristics
5.2.4 Sampling and measurement strategy issues
5.2.5 Conclusions from review of literature
6 Research Methodology
6.1 General Information
6.2 Instrumentation
6.3 Experimental design
6.4 Analyses
6.4.1 Transmission Electron Microscope, Scanning Electron Microscope and Energy-dispersive X-ray spectrometry
6.4.2 Thermal optical analysis of elemental carbon
6.4.3 Processing and Analysis of Data
7 Qualifying the Significance of the Results of Particle Measurement
7.1 Particle control values
7.1.1 Australian Workplace Exposure Standards
7.1.2 Recommended Exposure Limits
7.1.3 Proposed workplace exposure limits
7.1.4 Benchmark Exposure Level
7.1.5 Local Particle Reference Value
7.2 Criteria for assessing excursion above the particle control values
7.3 Factors that should be considered when comparing and interpreting particle measurement data
8 Results of the Characterisation of Particle Emission, Transport, Morphology, and Chemical Composition for Six Engineered Nanoparticle Aerosols
8.1 Mean particle metrics for all six nanomaterial aerosols
8.2 Process One – grinding and extrusion of modified TiO2
8.2.1 Experimental Design and Conditions
8.2.2 Results
8.2.2.1 Time series of particle number and mass concentration, count median diameter, and alveolar deposited surface area
8.2.2.2 Electron microscope
8.2.2.3 Discussion
8.3 Process Two – manufacture of clay-polyurethane nanocomposite material
8.3.1 Experimental Design and Conditions
8.3.2 Results
8.3.2.1 Time series of particle number and mass concentration, count median diameter, and alveolar deposited surface area
8.3.2.2 Influence of local extraction ventilation upon the particle concentration within the work area
8.3.2.2.1 Description of the local extraction ventilation servicing the extruder machine
8.3.2.3 Electron microscopy analysis of particles
8.3.2.4 Discussion
8.4 Process Three – grinding of titanium dioxide powder
8.4.1 Experimental Design and Conditions
8.4.2 Results
8.4.2.1 Time series of particle number and mass concentration, count median diameter, and alveolar deposited surface area
8.4.2.2 Discussion
8.5 Process Four – jet milling of modified clay particles
8.5.1 Experimental Design and Conditions
8.5.2 Results
8.5.2.1 Time series of particle number and mass concentration
8.5.2.2 Influence of local mechanical dilution ventilation upon the particle concentration within the work area
8.5.2.3 Discussion
8.6 Process Five – Decanting of single and multi-walled carbon nanotubes
8.6.1 Experimental Design and Conditions
8.6.2 Results
8.6.2.1 Time series of particle number and mass concentration, count median diameter, and alveolar deposited surface area
8.6.2.2 Electron microscopy analysis of particles
8.6.2.2.1 Methodology
8.6.2.2.2 Results
8.6.2.3 Estimating mass concentration of carbon nanotube aerosols - elemental carbon analysis and real time mass concentration measurements
8.6.2.4 Discussion
8.7 Process 6 – Synthesis of carbon nanotubes using Chemical Vapour Deposition
8.7.1 Experimental Design and Conditions
8.7.2 Results
8.7.2.1 Time series of particle number and mass concentration
8.7.2.2 Influence of process enclosure and fume cabinet upon the particle concentration within the work area
8.7.2.3 Discussion
9 Comparison and Evaluation of the Response of Different Instrumentation and Measurement Methodology to a Range of Airborne Engineered Particles
9.1 Methodology
9.2 Discussion
10 Discussion of, and Recommendations for, Characterisation and Reporting of Temporal and Spatial Concentrations of Airborne Engineered Nanoparticles
10.1 Recommendation 1: Utilise Particle Control Values when evaluating particle emission and exposure
10.1.1 Hierarchy of Particle Control Values for nanomaterials
10.2 Recommendation 2: Minimise the number of particle metrics to be characterised
10.3 Recommendation 3: Utilise real-time particle number and mass concentration data to identify sources of particle emission, spatial variation, and to validate effectiveness of engineering controls in containing particle emissions
10.4 Recommendation 4: comprehensively characterise background and incidental particle number and mass concentration
10.5 Recommendation 5 – utilise excursion guidance criteria relative to particle background to evaluate significance of temporal and spatial particle variation
10.5.1 Application of excursion guidance criteria to research data contained in this report
10.5.2 Examination of findings in relation to background particle reference values
10.5.3 Approach summary
10.6 Recommendation 6: Utilise a three-tiered particle evaluation process
10.6.1 Tier One - comprehensive survey of the process environment
10.6.1.1 Qualitative survey
10.6.1.2 Quantitative survey
10.6.2 Tier Two – comprehensive characterisation of real-time particle number and mass concentration
10.6.2.1 Characterisation of particle source emission
10.6.2.2 Estimation of exposure
10.6.2.3 Validation of effectiveness of particle emission controls
10.6.2.4 Summarising overall findings of Tier Two assessment
10.6.3 Tier Three - utilise sampling methods for off-line analysis of particle morphology, chemical composition, and mass concentration, and real-time SMPS
10.6.3.1 Collection of particles at emission point
10.6.3.2 Collection of particles in the breathing zone of workers
10.6.3.3 Case study of tier three assessment
10.7 Recommendation 7: calculate impact of instrument accuracy on measurement results
10.8 Recommendation 8: calibrate equipment
10.9 Recommendation 9: utilise same equipment for on-going measurement of same process
10.10 Recommendation 10: record and report the relative humidity and temperature of the work area
10.11 Recommendation 11: A minimum data set should be included in all reports of assessment of nanomaterial aerosol
11 References
12 Appendix A
13 Appendix B – Pearson’s Correlation Results
13.1 Grinding of titanium dioxide powder
13.2 Extrusion of titanium dioxide and polyethylene materials
13.3 Extrusion of clay platelets and polyurethane materials
13.4 Grinding of titanium dioxide powder
13.5 Jet milling of clay platelets
13.6 Decanting of single-walled carbon nanotube powder
13.7 Decanting of multi-walled carbon nanotube powder
14 Appendix C