Table 2: Distribution of selected particle characteristics and the allergy-promoting capacity for all particles tested (as measured by high levels of OVA-specific IgE and eosinophil airway inflammation). To simplify the identification of particle characteristics of importance for the modulated allergy responses after airway exposure, the levels of each particle property or allergic response are subjectively categorized into three levels, illustrated by roman, bold italic, or bold font.

Main carbon structureFraction of fibers/tubes versus disordered materialFiber/tube width (nm)Surface area (m2/g)Structural defects ( )Metallic contaminantsAllergy-promoting capacity

CNF AFibers, open channelsMedium37.01 ± 1.57 [11.25108.69] 1031.7High, mainly NiMedium
CNF BFibers, periodically closed channelsHigh83.14 ± 4.18  
18.90–302.21
610.7TracesMedium
CNF CFibers, open channelsLow35.82 ± 2.13 [14.46185.75] 1240.9High, mainly NiMedium
CNF DFibers, periodically closed channelsMedium70.57 ± 2.68 
18.52–286.85
560.6TracesMedium
swCNTTubes, open channelsMedium4.05 ± 0.23
[1.41–10.91 nm]
543n.a.High, mainly CoHigh
mwCNTTubes, open channelsHigh15.04 ± 0.47
[7.62–29.01 nm]
140n.a.Less, mainly Ni(Fe)High
ufCBPSphericalNot relevantNot relevant3211.2TracesMedium