BGS identified a requirement to develop methane and carbon dioxide gas emission data holdings in a format that would be suitable both for BGS GeoReports and for value added resellers, such as Landmark, so that information on methane (CH4) and carbon dioxide (CO2) gas emission hazards from natural sources and coal mining can be included in reports for house buyers and developers. Rock strata and unconsolidated deposits can be classified using BGS 1:50,000 scale DiGMapGB data (or 1:250,000 for those sectors of Wales for which 1:50,000 scale geological data is not availabe) according to their susceptibility to gas seepages.