Table 4

Factors affecting measured FeNO levels1

Factors which increase FeNOFactors that decrease FeNO
Allergic rhinitis in patients exposed to an allergen and atopic dermatitisCigarette smoking (acutely and cumulatively)
Increased heightChildhood (<12 years old). This is less important in adolescence and not significant in adulthood
Rhinovirus infection in healthy individuals
  • FeNO, fractional exhaled nitric oxide.