Introduction and Objectives It has been estimated that 15% of the population burden of chronic obstructive pulmonary disease population is attributable to occupational factors. Most of the evidence comes from studies conducted in high-income countries (HICs). Our aim was to examine the relationship between occupational exposures and respiratory health in both HICs and Low- and middle-income countries (LMICs) participating in the multinational, population-based, cross-sectional BOLD study.

Methods We analysed data from 28,823 adults aged ≥40 years who completed respiratory and occupational questionnaires and had acceptable and repeatable post-bronchodilator spirometry measurements. Occupational exposures comprised three categories (organic dust; inorganic dust; fume) and 11 high-risk occupations (farming; flour, feed or grain milling; cotton or jute processing; hard-rock mining; coal mining; sandblasting; working with asbestos; chemical or plastics manufacturing; foundry or steel milling; welding; and firefighting). The associations of respiratory symptoms and lung function with occupational exposures were estimated using multivariable regression models adjusted for potential confounders for each BOLD site and then pooled using meta-analysis. Sensitivity analyses by sex, national gross national income and smoking status were also performed.

Results We found that people working in any of three categories of occupational exposures and the 11 high-risk occupations under consideration were more likely to report respiratory symptoms than those who do not work in any of those occupations. Overall, we found no consistent associations between the occupational exposure categories and high-risk occupations and measures of lung function. Nevertheless, in sensitivity analyses, men in HICs exposed to organic dusts in the workplace for at least 20 years (median) had significantly decreased FEV₁/FVC (β=-0.34%; 95% CI -0.42% to -0.27%) and decreased FVC (β=-0.18L; 95% CI -0.32L to -0.04L). Men in LMICs exposed to fumes for at least 11 years had significantly decreased FEV₁/FVC (β=-0.29%; 95% CI -0.41% to -0.16%).

Conclusions In a large global study, we found respiratory symptoms to be associated with 11 high-risk occupations. The associations between occupational exposures and lung function varied by gross national income groups; more research is needed to understand these differences. Meanwhile, preventive measures and respiratory health surveillance should be enhanced among exposed workers.