SURVEY OF CONSTRUCTION WORKERS REPEATEDLY EXPOSED TO CHLORINE OVER A 3 TO 6 MONTH PERIOD IN A PULPMILL .2. FOLLOW-UP OF AFFECTED WORKERS BY QUESTIONNAIRE, SPIROMETRY, AND ASSESSMENT OF BRONCHIAL RESPONSIVENESS 18 TO 24 MONTHS AFTER EXPOSURE ENDED

Objective-The aim was to determine the prevalence of persistent respiratory symptoms and bronchial hyper-responsiveness due to reactive airways dysfunction syndrome in a population of construction workers at moderate to high Ask of developing the syndrome, at an interval of 18 to 24 months after multiple exposures to chlorine gas during renovations to a pulp and paper mill. Design and participants-71 of 289 exposed workers (25%) were identified on the basis of an exposure and the onset of respiratory symptoms shortly after this event (moderate to high risk). A standardised respiratory questionnaire was first presented, followed by spirometry and a methacholine inhalation test on those whose questionnaire suggested the persistence of respiratory symptoms. Results-64 of 71 (90%) subjects completed the respiratory questionnaire at the time of the follow up. The questionnaire suggested a persistence of respiratory symptoms in 58 of the 64 workers (91%). Of the 58 subjects, 51 underwent spirometry and assessment of bronchial responsiveness. All of them used bronchodilators as required (not regularly) and four required inhaled antiinflammatory preparations. Sixteen had bronchial obstruction (forced expiratory volume in one second) (FEV(1) < 80% predicted) and 29 showed significant bronchial hyper-responsiveness. Conclusion-Of the subjects (n = 71) who were at moderate to high risk of developing reactive airways dysfunction syndrome after being exposed to chlorine and were seen 18 to 24 months after exposure ended, 58 (82%) still had respiratory symptoms, 16 (23%) had evidence of bronchial obstruction, and 29 (41%) had bronchial hyper-responsiveness.