“…14,15 In patients with asthma and atopy, serum total and allergenspecific IgE levels, serum eosinophil cationic protein (ECP) levels, and peripheral blood eosinophils are all associated with increased FeNO levels. [16][17][18][19] In healthy adult subjects male sex, height, upper respiratory tract infection (URI), and nitrate intake have been associated with increased FeNO levels, [20][21][22][23][24][25][26][27] whereas cigarette smoking 28 and hypertension 29 have been associated with low FeNO levels. There are conflicting reports about whether age is associated with differences in FeNO levels in adults, 20,27 whereas in children there is more consensus that increasing age is associated with higher FeNO levels.…”