Changes in the composition of the cellular lipid pool are known to occur in response to various stimuli during cellular activation. However, long-term changes in the composition of this pool associated with the chronic inflammatory reaction, as seen in byssinosis, have not been assessed. In order to investigate such changes, we have developed methods for the screening of fatty acids obtained from lung lavage involving Fast Atom Bombardment Mass Spectrometry and Gas Chromatography-Mass Spectrometry. We now present data regarding the relative composition of fatty acids in the cellular fraction of bronchoscopic lung ravages obtained from human airways and discuss the implications of these findings for chronic byssinosis.