Smoking history was not associated with pulmonary function decline in smokers between 18 and 35 years, though there were functional and inflammatory changes in the nasal and lower airways, which do correlate with smoking history, according to published results in the journal Chest.

The authors note that it is unlikely spirometry detects early physiologic changes in the airways of this population.

Researchers measured nasal mucociliary clearance (MCC), nasal mucus surface contact angle, cell counts, myeloperoxidase and cytokine concentrations in nasal lavage fluid, exhaled breath condensate (EBC) pH and lung function in 32 healthy nonsmokers and 40 smokers.

Smokers had faster nasal mucociliary clearance with a mean nasal saccharine transport time of 5.9 minutes compared with 7.7 minutes in nonsmokers. This may be due to increased ciliary beat frequency as a protective response to smoking, according to the researchers.

Investigators also found that smokers had an increased number of cells in nasal lavage fluid (macrophages, ciliated, and goblet cells) and decreased EBC pH, which is thought to reflect an inflammatory response of the airways. Those who smoked for less than 2.5-pack-years had significantly higher myeloperoxidase levels in nasal lavage fluid than both healthy nonsmokers and those with greater smoking histories.

“The lower airway EBC pH decrease in these young smokers contrasts with the lack of changes in spirometry suggesting that … there may be inflammation without sufficient air flow limitation to produce COPD,” the authors concluded.