Respiratory diseases are strongly related with exposure in the workplace. A considerable proportion of adult onset asthma is associated with these exposures. The importance of occupational risk factors for asthma has been underestimated, particularly among women. The occupational asthma study (ECRHS-OA) forms part of a wider international multicentre survey on respiratory health (European Community Respiratory Health Survey-ECRHS). The first phase of the ECRHS was conducted in 1991/92 and examined risk factors for asthma and atopy in subjects aged 20-44 years. The study updated (ECRHS-II), following-up approximately 17,000 young adults from 12 countries (Australia, Belgium, France, Germany, Iceland, Italy, Norway, Spain, Sweden, Switzerland, UK and USA).