Further based on a recent study (Scadding et al, unpublished data; mean 70.14, standard deviation 14.17 for cross-sectional area in cm2 at 8 hours for skin late phase response to intradermal grass pollen injection), inclusion of 7 participants per group will provide 80% power to detect a 30% reduction, whereas inclusion of 10 participants per group will provide 90% power to detect a 30% reduction.