In the past year, many advances were made in occupational asthma (OA). As in previous years, several new causes of OA were described and the prevalences of some causes of OA were studied. Animal studies suggested possible mechanisms for the induction of sensitization to low-molecular-weight chemicals, and a study in humans indicated the ability of diisocyanates to bind with lung epithelial cells and stimulate mononuclear cells in sensitized patients with OA. New diagnostic and research methods, such as induced-sputum assessment and measurement of exhaled nitric oxide, were evaluated. The effectiveness of protective respiratory devices in patients with OA was shown to be suboptimal (although these devices are necessary in some cases), and the need to prevent OA by reducing or eliminating exposures remains paramount.