Exhaled breath condensate pH and FeNO as biomarkers of acute and chronic exposure to hazards at swine farms.

OBJECTIVE The noninvasive biomarkers of respiratory impairment were assessed in 15 swine confinement (SC) workers and 9 respiratory healthy, nonsmoking volunteers (HV). METHODS Spirometry, fraction of exhaled nitric oxide (FeNO), and exhaled breath condensate (EBC) pH were assessed in SC workers after one working shift and one working week and in HV after 5-hour exposure in SC. RESULTS Half of the respiratory symptoms (in 8 of 15 SC workers) were work-related. Basal FeNO values were 7.5 ppb higher in the SC workers compared with HV. In the SC workers, EBC pH increased for 0.17 at the end of a working week (P < 0.001). In HV, 5-hour exposure in SC induced 8% drop in forced expiratory flow at 25% of the pulmonary volume (FEF25) (P = 0.008), EBC pH drop for 0.10 units (P = 0.003), and FeNO drop by 1.8 ppb (P = 0.047). CONCLUSIONS EBC pH was suggested as a biomarker of acute airway acidification in HV, whereas the SC workers showed signs of the "healthy worker effect."