Clinical aspects of occupational asthma

In about 1 in 10 cases, new or recurrent asthma in adulthood will be caused by work. In many cases the asthma will arise from the action of non-specific airway irritants on a background of bronchial hyperreactivity; in others the mechanism is one of hypersensitivity to a specific agent for which the label ''occupational asthma'' is generally reserved. Some 300 different workplace agents are capable of inducing asthma but most cases are attributable to a far smaller number to which exposure is incurred in a few high-risk occupations. The clinical diagnosis of occupational asthma is usually straightforward; problems occur in patients with pre-existing asthma or in those with unusual exposures, especially if these are to low molecular weight agents. Management is more difficult since there are often important employment and other social issues to be taken into account.