This paper describes an on-going project to develop robotic systems for locating chemical sources in constrained environments. There is increasing interest in applying chemical sensing to mobile robots. Locating the source of a chemical plume is seen as an important use for a chemical sensing robot. Current research tends to concentrate on source location in open and relatively obstacle free environments. Many of the applications for this technology will be areas where airflow is constrained and deflected by obstacles such as inside buildings, mines and subway tunnels. It is this kind of situation that this project aims to address.