Bronchial reactivity in a general population of north Italy: relationships with occupational exposure

Two thousand eight hundred and forty one subjects, aged 8-73 yrs, took part in the second cross-sectional survey in the Po River Delta area: among them, a subsample of currently employed people, aged 14-71 yrs, was chosen to establish the relationship between occupational exposure to dusts, chemicals or gases and respiratory symptoms, lung function and bronchial reactivity. Each subject filled out the Italian National Research Council (CNR) standardized questionnaire concerning respiratory symptoms, diseases and risk factors. A variable proportion of subjects performed acceptable forced and slow vital capacity manoeuvres, diffusing capacity of carbon monoxide and bronchial challenge test to methacholine. Occupational exposure appeared to be related to prevalence rate of respiratory symptoms (wheeze, dyspnoea, presence of at least one respiratory symptom) and bronchial asthma. Consistent effects on lung function were not evident. With respect to the bronchial challenge test, using the measurement of the provocative dose producing a 20% fall in forced expiratory volume in one second (PD20) a significantly higher percentage of hyperreactive subjects was found among ex-smoker exposed men; a borderline higher percentage of hyperreactive subjects was also found in non-smoker exposed women. The study findings support the suggestion that occupational exposure may play a role in the development of airway obstructive diseases.