Prevention of occupational asthma.

Occupational asthma (OA) is a type of bronchial asthma due to causes and conditions attributable to a particular occupational environment. It is the most prevalent occupational lung disease in industrialized countries, accounting for approximately 5% of asthma in adults. Since OA has important medical, social and economic consequences, its prevention is mandatory, and the most important measure is primary prevention at the workplace. Control of environmental exposure can be realized by completely eliminating the causative substances, or, failing that, by reducing exposure to the lowest practicable levels. This goal may be achieved in a variety of ways, e.g. by automation of a process, improvement of ventilation, modification of the process or agents, and use of personal protection devices. However, the control of environmental exposure presents several difficulties. First of all, exposure levels that favour respiratory sensitization to high molecular weight (HMW) or low molecular weight (LMW) agents are not completely defined. There is a critical need for the development of methods able to quantify the airbone levels of sensitizing agents at the workplace and to establish limits of exposure for respiratory sensitization. Development of assays (e.g. immunochemical assays) able to quantify airbone allergen levels should facilitate determination both of exposure-response relationships and of exposure limits for preventing respiratory sensitization and development of OA. Quantification of risk at the workplace is also often rough and based on indirect markers of exposure. At present, the target for an optimal approach to the primary prevention of OA is the development of methods able to evaluate both the sensitizing and the asthmogenic properties of the substances before their introduction in the work environment.