Asthma is a multifactorial disease and environmental influences have long been associated with its everyday symptoms. In recent years it has been proposed that environmental factors can also influence the actual development of the disease. Underlying genetic factors may interact with these common environmental factors. Thus, the environment may be involved in both the aetiology and the symptomatic manifestations of the disease. The discussion is completed by looking at the role of local authority Environmental Health Officers (EHOs) in combating asthma.