Cross-shift Reduction in Fractional Exhaled Nitric Oxide among Cement Workers

Objective: Assessment of changes in fractional exhaled nitric oxide (FENO) across the shift was performed among cement production workers and controls. FENO was used as a possible marker of eosinophilic inflammation in the airways. In addition, the relations between personal total dust exposure and FENO changes across the work shift were examined. Methods: Pre-and post-shift FENO levels were determined among 55 non-smoking dust exposed cement production workers and among 31 non-smoking mineral water factory workers as controls. The FENO levels were examined for three consecutive days among the exposed and two consecutive days among controls. Personal total dust levels were collected in the breathing zone of each participant using cellulose acetate filters on the first day of FENO examination. A three-piece Millipore cassette was used to place the filters and the cassette was connected to a Side Kick Cassela pump at a flow rate of 2 l/minute. Results: There was a statistically significant reduction in FENO levels among exposed workers, but not among controls. The reduction in FENO levels among the exposed was observed on each day of FENO examination. The cross-shift reduction in FENO levels among the exposed did not show possible associations with personal total dust exposure levels (r=-0.175, 95% CI: -0.36, 0.04). The geometrical mean for total dust exposure were 8.3 mg/m3 and 0.28 mg/m3, among exposed workers and controls, respectively. Conclusion: The results show a cross-shift reduction of FENO among cement workers and indicate that dust exposure is not associated with this finding. The reason for the reduction in FENO across the shift is unknown. Researchers in this field should be aware of potential unknown confounders when performing future studies.