ABSTRACT
Fraction of exhaled nitric oxide (FENO) has gained a lot of interest as a biomarker for inammation since it was discovered in exhaled air at the beginning of the 1990s. Nonetheless, its utility in occupational lung disease is not fully established. The current concept underlying the relevance of FENO is that it is linked to Th2-driven inammation (Bjermer et al., 2014) and thereby to eosinophilic airway inammation. Numerous studies have shown that FENO is associated with eosinophils in sputum and in bronchoalveolar lavage (BAL), even if this association is only modest (Berry et al., 2005), whereas the association of FENO with the blood eosinophil concentration is poor. In the occupational lung disease eld, FENO has mainly been used in cross-sectional studies and in combination with specic inhalation challenge (SIC) testing. The results of these studies are summarized below.
