Exhaled nitric oxide among pulpmill workers reporting gassing incidents involving ozone and chlorine dioxide

Abstract

The aim of the study was to investigate whether measurement of nitric oxide in exhaled air could be used for assessing the effects of irritants on the respiratory system, in this case recurrent ozone gassing in an occupational setting.The study population comprised bleachery workers (n=56) from a Swedish pulpmill carrying out ozone-based pulp bleaching since 1992 and controls (n=39). Both groups were investigated by measuring NO in exhaled air, methacholine challenge test and answers to a questionnaire concerning history of respiratory symptoms and accidental exposure to ozone peaks.There was no significant difference in NO output between exposed subjects and controls (median 67.2 versus 55.0 nL . min -1 , p=0.64). However, among bleachery workers reporting ozone gassings, the median NO output was 90.0 nL . min -1 compared to 58.8 nL . min -1 among those not reporting such incidents (p=0.019). There was no relation between exhaled NO and the prevalence of respiratory symptoms or bronchial hyperresponsiveness. In a multiple regression model, only reported ozone gassings were associated (p=0.016) with NO output.The results indicate an association between previous response to ozone gassing and nitric oxide output. The increased nitric oxide output among the bleachery workers reporting peak ozone exposure may indicate that chronic airway inflammation is present. Further studies are needed to evaluate the extent to which nitric oxide can be used for biological monitoring of respiratory health effects, and to relate it to other markers of airway inflammation. Eur Respir J 1999; 14: 828±831.

Incidence of asthma among workers exposed to sulphur dioxide and other irritant gases

“…There is a longitudinal study from Quebec, Canada, showing that Cl 2 gassings increase airway responsiveness [26,27]. OLIN and coworkers [28][29][30] found increased nitric oxide in exhaled air among bleachery workers reporting ozone gassings, which may indicate chronic airway inflammation. Irritants are known to trigger inflammation through epithelial injury, but it has also been proposed that neuronal activity through neuropeptides gives rise to, and maintains, inflammation (i.e.…”

Exposure to ozone gases in pulp mills and the onset of rhinitis

“…Follow-up began for all the workers in 1992 and continued until either 1996 or the year of reported onset of rhinitis, whichever came first. Additional information on selection of the participants can be found elsewhere (4,5).…”

“…Workers are sometimes exposed to these gases at high levels due to accidental leakage. Several studies have shown an increase in lower respiratory symptoms due to these accidental gassings (2)(3)(4)(5). In addition, Olin et al (4) reported an increase in exhaled nitric oxide, which indicates possible respiratory inflammation, after exposure to ozone gassings.…”

Airflow limitation and changes in pulmonary function among bleachery workers

“…Each subject performed at least three technically acceptable trials, and the largest values for FVC and FEV1 were retained and compared with predicted values [18]. Details of spirometry measurements are documented in previous studies [14,15]. Each subject's average annual changes in FEV1 (DFEV1), FVC (DFVC), and FEV1/FVC (DFEV1/FVC) were calculated using the following equation:…”

“…In a study at one Swedish pulp mill, investigators found increased exhaled nitric oxide among bleachery workers reporting ozone gassings, suggesting airways inflammation may have been present [14]. The investigators also reported that the forced expiratory volume in one second (FEV1) was lower for bleachery workers compared with process workers from the adjacent paper mill (97.6% versus 104.0% predicted; p50.007), while there was no difference between the two groups in forced vital capacity (FVC) [14]. When comparisons were limited to the bleachery workers, those who reported ozone gassings did not have lower FEV1 or FVC.…”