Occupational asthma in Europe and other industrialised areas: a population-based study

Background There are no large population-based studies on occupational asthma, and few estimates of the proportion of asthma attributed to occupation, even though asthma is the most common occupational respiratory disorder in industrialised countries. Methods We assessed data on 15637 people aged 20–44, randomly selected from the general population of 26 areas in 12 industrialised countries. Asthma was assessed by methacholine challenge test and by questionnaire data on respiratory symptoms and use of medication. Occupation was defined by job-titles and a job exposure matrix was constructed. Findings Highest risk of asthma, defined as bronchial hyperresponsiveness and reported asthma symptoms or medication, was shown for farmers (odds ratio 2·62 [95% CI 1·29–5·35]), painters (2·34 [1·04–5·28]), plastic workers (2·20 [0·59–8·29]), cleaners (1·97 [1·33–2·92]), spray painters (1·96 [0·72–5·34]), and agricultural workers (1·79 [1·02–3·16]). Similar risks were shown for asthma defined as reported asthma symptoms or medication. The most consistent results across countries were shown for farmers and cleaners. Excess asthma risk was associated with high exposure to biological dusts, mineral dusts, and gases and fumes. The proportion of asthma among young adults attributed to occupation was 5%–10%. Interpretation The prevalence of occupational asthma in women and in specific occupations has been underestimated. Given a mean prevalence of asthma of about 5%, about 0·2%–0·5% of young adults become asthmatics or have their asthma exacerbated because of their occupations.