Background Foundry work may involve exposure to respiratory sensitisers and irritants. There is limited evidence for the use of FENO in occupational settings, and particularly in foundries.
Aim To examine the usefulness of FENO in identifying foundry workers at risk of asthma.
Methods Foundry workers undertook a respiratory questionnaire. Spirometry (Ndd Easy on-PC Spirometer, Zurich) and FENO (NOBreath, Bedfont Scientific, Kent) were measured to ATS/ERS standards. The ATS upper limit of normal (ULN) of 50 parts per billion (ppb), or 45.9ppb for current smokers, determined the high FENO category (FENO >ULN). Workers with FENO >ULN were compared with those with at least one work-related respiratory symptom (WRRS) and those with obstructive lung function (FEV1/FVC <0.7) using Chi Square and Fisher’s Exact Tests.
Results 351 workers (350 men, 99%) participated. 350 workers had a valid FENO performed. Arithmetic mean FENO was 30.2ppb (95% CI: 27.3–33.2); geometric mean (GM) FENO20.8 (18.9–22.9) ppb.
FENO exceeded the ULN in 61 (17%) workers. Average age for the FENO >ULN group was 41.5 (95% CI: 38.3–44.7), with a mean of 15.8 (12.4 – 19.2) years working in the foundry industry.
Workers in the FENO >ULN group were significantly more likely to have a current diagnosis of asthma (12% vs 5%, p < 0.05), have ever suffered allergies (55% vs 31%, p < 0.01), or report work-related shortness of breath (3% vs 0%, p < 0.05).
Fourteen workers (4%) had a FENO >ULN and WRRS (Figure1). Of these 14, only 2 (14%) had a current diagnosis of asthma (Fisher’s p = 0.20). Eight (2%) workers had a FENO > ULN and FEV1/FVC <0.7, though only 2 (25%) had a current asthma diagnosis (Fisher’s p = 0.08).
Conclusion A significant proportion of foundry workers have FENO levels that exceed the ATS cut point for likely eosinophilic airway inflammation. Of these workers, most had a raised FENO but no WRRS or obstructive lung disease. Only a minority of workers with FENO >ULN and either WRRS or obstruction had a current diagnosis of asthma. FENO may be useful in identifying foundry workers at risk of asthma and warrants further study.