Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in the world. UK statistics show that it is the third biggest cause of respiratory deaths, accounting for 23% of all respiratory deaths.1 In the USA COPD is the fourth leading cause of chronic morbidity and mortality.2 A study by the World Bank/World Health Organization predicted COPD to be the fifth leading cause of worldwide burden of disease in 2020.3 The role of tobacco smoking in the decline in lung function was shown in the classic study by Fletcher and Peto4 in the 1970s, and the US Surgeon General’s Report on smoking and COPD in 1984 established smoking as a causal factor for COPD.5 Epidemiological studies also reported a link between occupational exposures and chronic bronchitis as early as the 1940s and 1950s,6 7 but the role of occupation received less attention until Becklake8 highlighted the evidence for a causal association between occupational exposures and COPD in a review article in 1989.

Clinicians frequently encounter patients who themselves relate their respiratory symptoms to dusts or fumes in the workplace. Although almost two decades have passed since Becklake concluded that dust exposure at work is a causal factor for COPD,8 clinicians have still been left with considerable uncertainty concerning what advice to give to their patients, apart from the very general opinion that it is always good to reduce dust levels.

The early studies addressed the relationship between specific occupational exposures and COPD in workforce-based studies.8 9 To reduce potential healthy worker bias (ie, selection bias due to the possibility that people entering dusty and fumy jobs or remaining in them may be healthier …