Short and long-term effects of cigarette smoking independently influence exhaled nitric oxide concentration in asthma

J Allergy Clin Immunol. 2005 Jul;116(1):88-93. doi: 10.1016/j.jaci.2005.03.025.


Background: The fractional concentration of nitric oxide in exhaled breath (FeNO) is elevated in asthma. FeNO measurement has been proposed as a noninvasive index of disease activity. Cigarette smoking suppresses FeNO, which limits its use in smokers.

Objective: To identify and model short-term and long-term influences of cigarette smoking on FeNO.

Methods: The smoking history, FeNO, and fractional concentration of carbon monoxide in exhaled breath (FeCO) were measured in 53 subjects with asthma and 51 control subjects. A mathematical model of the short-term and long-term effects of cigarette smoking on FeNO was derived.

Results: Subjects with asthma had higher FeNO than controls ( P < .001). Smokers had increased FeCO ( P < .001). The short-term effect (hours since last cigarette) was associated with increased FeNO ( P < .01) and decreased FeCO ( P < .05). The long-term effect (years smoked) was associated with decreasing FeNO only in the subjects with asthma ( r = -0.62; P = .005). These short-term and long-term effects were independent and were combined in a model predicting FeNO, predicted log 10 FeNO = 1.23 - 0.58 e -0.34t - 0.00000103 x (lifetime cigarettes), where t = hours since the last cigarette. This gave a convincing prediction of FeNO ( r = 0.83; P < .0001).

Conclusion: Short-term and long-term effects of smoking influenced the measurement of FeNO. We defined a model that describes these effects. The use of this formula may improve the value of FeNO measurements in smokers with asthma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Asthma / physiopathology*
  • Breath Tests
  • Carbon Monoxide / analysis
  • Cross-Sectional Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Models, Theoretical*
  • Nitric Oxide / analysis*
  • Smoking / adverse effects*
  • Spirometry
  • Time Factors


  • Nitric Oxide
  • Carbon Monoxide