Lead is a highly toxic metal that is pervasive in the environment in industrialised countries. There is universal agreement that at some level of exposure, lead damages the haematopoietic, renal, and neurological systems. However there is less agreement about how much lead can be tolerated without harm. The use of leaded petrol was phased out between 1976 and 1996 in the United States, and was eliminated in the European Union by 2000, but concern is growing that petrol remains an important source of exposure in many countries, especially in Africa and Asia. Motivated by this concern, the Seychelles Bureau of Standards implemented an air quality monitoring project to measure airborne lead in Victoria, the capital, beginning in January 1998. In this paper, we describe the potential dangers of human exposure to lead, focusing on the neurobehavioural effects in children. We describe some of the common and not so common sources of lead in the environment, emphasizing exposure from inhalation of airborne lead particles from automobile exhaust. The Seychelles Ambient Air Quality Monitoring Programme is described, including the collection and analytical methods used to measure the lead concentrations in these samples. We present the findings from this investigation and discuss their public health implications.