Exposure-response relationships between occupational exposures and chronic respiratory illness: a community-based study.

Data from a random sample of 3,606 adults 40 to 69 yr of age residing in Beijing, China, were analyzed to investigate the association of reported occupational exposures to dusts and gases/fumes with the prevalence of chronic respiratory symptoms and level of pulmonary function. The prevalence of occupational dust exposure was 32%, and gas or fume exposure, 19%. After we adjusted for age, sex, area of residence, smoking status, coal stove heating, and education, an increased prevalence of chronic phlegm and breathlessness was significantly related to both types of exposures. Chronic cough was significantly related only to dust exposure, and persistent wheeze only to fume exposure. The global estimates of the relative odds of the four symptoms were 1.30 (95% CI [confidence interval] 1.09 to 1.48) and 1.27 (95% CI 1.09 to 1.48), respectively, for dusts and for gases/fumes. These two occupational exposures are associated with chronic respiratory symptoms independent of smoking, gender, and each other. There was an increasing prevalence of each symptom with increasing dust and fume exposure, represented by the index of cumulative exposure duration and exposure intensity. Linear trends for increased prevalence of chronic bronchitis and breathlessness were significant for both exposures, while the linear trend for wheeze was only significant for gases/fumes. Among subjects who did not report using coal stove heating, dust exposure was a significant predictor for FEV1, FEV1/FVC, FEF25-75, and peak expiratory flow rate (PEFR). There was also a significant decrease for FEV1 and FVC with increase of gas/fume exposure levels. Both current and former smokers appeared to be more susceptible to the effect of dusts than the never smokers.(ABSTRACT TRUNCATED AT 250 WORDS)