Exposure to wood dust is a common occurrence in all countries and may cause various diseases. These include extrinsic allergic alveolitis, organic dust toxic syndrome, occupational asthma, non-asthmatic chronic airflow obstruction, and simple chronic bronchitis (mucus hypersecretion). Of these conditions, the most common are simple chronic bronchitis and non-asthmatic chronic airflow obstruction. The level and pattern of occurrence of these conditions varies with the type of wood dust, climatic conditions, and the manner in which it is handled, particularly the use of fungicides. The prevalence and characteristics of the conditions associated with wood dust exposure are very similar to those due to grain dust exposure.