The growing sensibility on health has focused people interest on the air quality. Small monitoring systems are inexpensive solutions, requiring minimal equipment and installation time. In urban environment, as well as in special indoor areas, the air quality levels suffer from both time and space variations even over a very short scale. From this point of view, mobile sensors would allow for a more exhaustive mapping of the region of interest, including information of the dynamics affecting the possible pollution. However, the cost of the monitoring could become unacceptably high if the mobile robots must be controlled by human operators. This research proposes an autonomous guidance, navigation and control system for mapping the state and evolution of the pollution by means of a set of sensors (measuring LPE, CO, CO2, CH4, H2, NH4) purposely developed and mounted on a wheeled rover. GPS, inertial measurement units and stereo vision enable autonomous navigation of the monitoring system, proved to be effective in the presented tests.