The effect of exhalation flow on endogenous particle emission and phospholipid composition.

•Exhaled particles have potential as a tool for monitoring respiratory disease.•This potential would increase if particle formation was better understood.•Maximal forced exhalation generate particles mainly in central or upper airways.•Deep exhalations and inhalations generate particles mainly in small airways.•Particles from small airways contain a higher concentration of alveolar surfactant.