(51)In order to reflect the average characteristics of non-life insurance obligations, the modelling of mass accident risk in the standard formula should be based on the assumption that the exposure of insurance and reinsurance undertakings to mass accident risk situated in third countries, other than specific European countries, is not material for the insurance and reinsurance undertakings and insurance groups subject to Directive 2009/138/EC. It should also be based on the assumption that the mass accident risk in relation to workers' compensation insurance is not material