Occupational and environmental lung disease is a vast topic. Therefore, this review focuses on areas that represent new clinical insights that have not been addressed recently in Current Opinion in Pulmonary Medicine. The topics are considered important for the future and emphasize diseases that strike large numbers of people or exposures that affect large segments of the population. This review highlights literature published between the years 2000 to 2001 related to air pollution, occupational asthma, lung diseases in agricultural workers, nylon flock workers lung disease, pneumoconiosis, and environmental exposure to biomass smoke, including environmental tobacco smoke. These publications highlight the changing world of occupational and environmental lung diseases. Traditionally, this field dealt with chronic diseases caused by very high levels of exposure to materials that affected virtually all workers to a similar degree. Disease could be recognized readily by characteristic symptoms, signs, and radiographic abnormalities. Dose-effect relationships were usually clear, and the solution to disease was generally to limit exposure for all workers. This approach served well for conditions such as coal workers pneumoconiosis or toxic responses to chlorine gas. The new world of occupational and environmental lung diseases often involves low levels of exposure to complex mixtures of materials that produce nonspecific or intermittent symptoms in a subgroup of exposed individuals. Interactions between genetic susceptibility, concomitant tobacco smoke exposure, and co-morbid diseases hugely complicate both diagnosis and prevention. New tools, and possibly new thought paradigms, are needed to detect, treat, and prevent occupational and environmental lung diseases in a changing world.