Exhaled nitric oxide in 4-year-old children: relationship with asthma and atopy

To the Editors: The paper by Brussee et al . 1 describes the first large survey of the fraction of exhaled nitric oxide ( F eNO) in a young population. The authors should be congratulated for undertaking such a study in an age range where great patience and persistence are required to obtain data. Brussee et al . 1 reported only a marginal increase in F eNO among atopic and asthmatic children compared with the nonatopic nonasthmatic children studied. One explanation for the large overlap in the distribution of F eNO in children with and without …