In asthmatic children, fruit and vegetable index was negatively associated with IL-8 levels in nasal lavage (P=0.013); Mediterranean diet index was positively associated with FEV1 (P=0.045) and FVC (P=0.018). Fruit and vegetable index was a significant modifier for the effect of ozone on FEV1 (P=0.023) and FVC (P=0.008) and Mediterranean diet was a modifier for the effect of ozone on FVC (P=0.02).