Occupational asthma remains a common disease in the UK with up to 3000 new cases diagnosed each year. The Health and Safety Executive (HSE) estimates the cost to our society to be over £1.1 billion for each 10-year period.1 In October 2001 the Health and Safety Commission agreed a package of measures aimed at reducing the incidence of asthma caused by exposure to substances in the workplace by 30% by 2010. Key to this aim are primary prevention by proper risk assessment and exposure control, together with secondary prevention to ensure reduction in the delay between the development of allergic symptoms at work (normally nasal or respiratory) and appropriate advice to the affected worker and workplace.

Conservative estimates suggest that one in 10 cases of adult onset asthma relate directly to sensitisation in the workplace,2 with a smaller subset of workers with acute irritant induced asthma. The latter—formerly termed reactive airway dysfunction syndrome (RADS)—relates to asthma caused by exposure to high levels of airborne irritants.

The prognosis of individuals with occupational asthma is better if they are removed from exposure quickly, particularly within a year of first symptoms.3^–5 However, removing individuals often leads to unemployment. If the diagnosis of occupational asthma is incorrect, advising individuals whose asthma is not caused by work to be removed from exposure may have unnecessary financial and social consequences.

• The reported incidence of occupational asthma may be underestimated by as much as 50% (ES3* SIGN 3). (ES, Evidence Statement with original BOHRF reference number6 as suffix.)

SCOPE AND BACKGROUND

The intent of this article is not to document the entire current evidence base related to occupational asthma, as the British Occupational Health Research Foundation (BOHRF) recently completed such an evidence review.7 The key points of this article are summarised in box …