[The prevalence of chronic obstructive pulmonary disease and asthma. A cross-sectional study].

Four hundred sixty-seven patients between 35 and 65 years of age were studied, all taken from a random sample of the population of Health Area 5 of the Valencian Community. Figures for respiratory symptoms, smoking, previous lung disease, professional activity and lung function were obtained through questionnaires and spirometry. The prevalence of asthma found was 2.78% (C.I. 2.76-2.79); chronic bronchitis was 4.07% (C.I. 2.37-5.77) and airflow limitation was 6.4% (C.I. 4.5-8.3). Smokers represented 33.2% of the sample. A significant association was found between the level of intensity of symptoms and lung function. There were no differences between smokers and non smokers with respect to FEV1%. An association between workplace exposure and spirometry was found only for FEV1/FVC%.