ForewordIntroductionScopeNormative referencesTerms and definitionsAbbreviated termsConsiderations in CNT and CNF inhalation studiesGeneralWorkplace exposure scenarioExisting inhalation toxicity testing guidelinesPhysicochemical parameters related to the toxicity of CNTs and CNFsGeneralAerodynamic properties of aerosols for deposition of fibresSize and shape (including length, width, aspect ratio, state of aggregation/agglomeration, and rigidity)Specific surface areaCrystalline structure and defectsSurface chemistry, functionalization, surface charge, impurities, and radical generation/scavenging potentialBiodurabilityIssues for the characterization of CNT and CNF aerosolsGeneralCharacterization of physicochemical properties of CNT and CNF prior to aerosol generationGeneralSize and size distributionShape (rigidity and agglomeration/aggregation)Surface areaCrystalline structuresSurface chemistry, functionalization, surface charge, and radical generation/scavenging potentialComposition, purity, and impuritiesBiodurability (in vivo and in vitro tests)CNT and CNF aerosol characterization (sampling and measurement)GeneralSize and size distribution of CNT and CNF aerosolsGeneralMass median aerodynamic diameterCount median diameterCount median lengthThe shape of CNT and CNF aerosolsGeneralAspect ratioAggregation/agglomeration in the aerosol stateRigidityCrystalline structure and defectsSurface chemistryComposition analysisFibre densityConcentrationGeneralMassNumberSurface areaDirect and indirect measurementDirect measurementIndirect measurementPhysicochemical properties of CNT associated with biological activity (informative)CNT and CNF aerosol monitoring instruments (informative)Bibliography