An Aero-Laser AL5001 instrument for the measurement of carbon monoxide mixing ratios in background air has been installed at the National Centre for Atmospheric Science (NCAS) Cape Verde Atmospheric Observatory (CVAO) since October 2006 and there are no plans for the measurements to stop in the foreseeable future. At the University of York we also have an AL5002 instrument which is used for shorter deployments (e.g. for NAMBLEX and OP3 and has in the past been used as a back-up for both the Cape Verde system and the FAAM aircraft system.