Nanosafety assessment methodology

1. Nanosafety assessment methodology Kaarle Hämeri Professor in Aerosol physics University of Helsinki Finnish Institute for Occupational Health

2. Take home -message • Aerosol particles have wide range of sizes and other properties • Exposure assessment requires determination of relevant aerosol characteristics using right measurement techniques

3. Content • Exposure • Health effects • Aerosol particle properties: • Number • Size • Surface area • Case studies

4. Exposure assessment • Analysis of processes leading to human contact to pollutants after release: • inhalation, ingestion, dermal contact • Exposure - Event when there is contact with human and environment with pollutant for an interval of time • Dose - Amount of contaminant absorbed or deposited in the body

5. winter summer

7. Condensation particle counter (CPC) • Single particle is illuminated with laser and light scattering is measured. • Before counting, particles are grown by condensation process TSI CPC model 3776 TSI CPC model 3007

8. Particle properties: Size Shape (Shape factor χ) Surface area porosity Volume Mass, density Chemical compositon Hydrophobicity, solubility Surface charge Electromagnetic properties Collective properties: Mass concentration (μg/m3) Number concentration (1/cm3) Surface area (m2/m3) Size distribution (number, surface area, mass) Aerosol particle properties

9. Different sizes • Aerodynamic size • Impactor, APS • shape, density, size • Electrical mobility size • Electrostatic classification • shape, size • Optical size • Amount of scattered light • refractive index, shape, size • Geometric size • Microscope

10. Size and shape depends on the detection method and the physical principle used Kuva: Mikko Moisio Dekati Oy

11. Qsheath + Qexcess R ≈ Qaerosol + Qclassified Differential Mobility Analysis Qaerosol Qsheath Qexhaust E Qclassified • Aerosol particles are charged by gas ions • Charged particles migrate across a particle-free • sheath flow • Particles within a narrow range of mobilities • migrate to a sample flow where they are • extracted for counting • Pecision is determined by flow rates • Resolution is approximately

12. scanning mobility particle sizer, SMPS • Neutraliser, DMA and CPC (+ high voltage supply and flow controls)

15. NANO-DMPS CPC-PAIR APS ΔT CPC IMPACTOR FMPS AIS

16. Analogy Particle size classes 1 nm – 100 µm -> Football hall vs. globe Or spoonful vs. km3 (1012 l) Need for investigations of: -several properties, several intruments and methods...

17. Number Surface area Volume

18. Nanoparticle surface area monitor • Detects particles between 10 nm and 1 µm • Concentration range 0.01-2500 µm2/cm3 • 1 s time resolution • Counter-flow diffusion charging of particles • Detection of the total charge (corresponds to total active surface, condensation sink)

20. Nanoparticles Consepts of nanoparticles (NP) (~1 nm < Dp < 100 nm): • Natural NPs, i.e. ultrafine particles (UFP) (from vegetation, sea, volcanoes, …) • Incidental NPs (UFP) (combustion, cooking, welding, …) • Engineered NPs (NPs, purposely manufactured) NPs at work place: • Measurements are needed for exposure assessment and to control emissions. • NPs are concidered to be potentially most harmful for health. • In occupational environment inhalation is the most significant exposure route for nanoparticles.

21. Health effects • Mass? • Number? • Surface area? • Composition? Importance of the size distribution!

22. Main open questions: • Are engineered nanoparticles harmful and how harmful? • Main sources and emissions? • Health relevant properties and measurables? • What type of detectors and instruments should be used in determining exposure? • Chain: emission-concentration-exposure-dose-effect

23. Lung deposition Nanomaterials (CNTs, agglomerates, …) ENPs Lung deposition curves defined by International Comission on Radiological Protection

25. Occupational aerosols

29. Suburban, natural ventilation Suburban, mechanical ventilation Urban, high mech. ventilation Urban, low mech. ventilation

30. Paint shop

31. Particle concentration time series during the work day Nanocollection Nanocoatings TiO2 CuxOy MnxOy MnxOy

32. Particle size distribution time series Particles from burning of impurities Nanoparticles 1 Background particles 3 Residual particle Nucleated particles

33. Respirator protection factor Assigned protection factor (APF) Level of respiratory protection that can be expected to be achieved in the work place by 95% of adequately trained and supervised wearers using a properly functioning and correctly fitted respiratory protective device (European standard: EN529). TH2 class: APF = 20 Schematic of Filter Efficiency vs. Particle Size TH3 class: APF = 200

34. Summary Concentration levels • Discrimination of NPs from background particles is challenging • Contribution of NPs to particle number concentration was ~99% and to mass concentration was < 0.01% Exposure • 70 % of particles were deposited in alveolar region where ~99% was NPs • 70 % of mass was deposited in head airways where <0.01% was NPs Recommendations Mass concentration is not proper metric in exposure assessment for synthesized NPs.