Tobacco smoking increases dramatically air concentrations of endotoxin.

We used a mass spectrometry-based assay for identifying the endotoxin (lipopolysaccharide, LPS) marker (R)-3-hydroxytetradecanoic acid in cigarette smoke particles and found that smoking involved inhalation of 17.4 pmol of endotoxin per each smoked cigarette. Indoor exposure to environmental tobacco smoke (ETS) entailed inhalation of 12.1 pmol of LPS/m3 air, an amount that was 120 times higher than the levels found in smoke-free indoor air. Endotoxin is one of the most potent inflammatory agents known, hence our results may help to explain the high prevalence of respiratory disorders among smokers, and they may also draw attention to a hitherto unknown or neglected risk factor of ETS