Nanosafety assessment methodology

1. Nanosafety assessment methodology Kaarle Hämeri Professor in Aerosolphysics 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 andenvironment with pollutant for an interval of time • Dose-Amount of contaminant absorbed or deposited in thebody

5. winter summer

7. Condensation particle counter (CPC) • Single particle is illuminatedwith laser and lightscattering is measured. • Beforecounting, particlesaregrownbycondensationprocess 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. scanningmobilityparticlesizer, SMPS • Neutraliser, DMA and CPC (+highvoltagesupply and flowcontrols)

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)

21. 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) NPsat workplace: • Measurementsareneeded for exposureassessment and to controlemissions. • NPsareconcidered to bepotentiallymostharmful forhealth. • In occupationalenvironmentinhalation is the mostsignificantexposureroute for nanoparticles.

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

23. Main openquestions: • Areengineerednanoparticlesharmful and howharmful? • Main sources and emissions? • Health relevantproperties and measurables? • Whattype of detectors and instrumentsshouldbeused in determiningexposure? • Chain: emission-concentration-exposure-dose-effect

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

26. Occupationalaerosols

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

32. Paint shop

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

34. Particle size distribution time series Particlesfromburning of impurities Nanoparticles 1 Background particles Residual particle Nucleated particles

35. Respiratorprotectionfactor Assignedprotectionfactor (APF) Level of respiratoryprotectionthatcanbeexpected to beachieved in the workplaceby 95% of adequatelytrained and supervisedwearersusing a properlyfunctioning and correctlyfittedrespiratoryprotectivedevice (Europeanstandard: EN529). TH2 class: APF = 20 Schematic of FilterEfficiency vs. ParticleSize TH3 class: APF = 200

36. Summary Concentrationlevels • Discrimination of NPsfrombackgroundparticles is challenging • Contribution of NPs to particlenumberconcentrationwas ~99% and to massconcentrationwas < 0.01% Exposure • 70 % of particlesweredeposited in alveolarregionwhere ~99% wasNPs • 70 % of masswasdeposited in headairwayswhere <0.01% wasNPs Recommendations Massconcentration is notpropermetric in exposureassessment for synthesizedNPs.