Yorkshire Ambulance Service NHS Trust (YAS) is the NHS ambulance service covering most of Yorkshire in England. It is one of ten NHS Ambulance Trusts providing England with emergency medical services as part of the National Health Service it receives direct government funding for its role. It was formed on 1 July 2006 following the mergers of the former West Yorkshire Metropolitan Ambulance Service (WYMAS), South Yorkshire Ambulance Service (SYAS) and some services from the Tees, East and North Yorkshire Ambulance Service (TENYAS).