Employers have the right to reject certain persons for employment because of physical disabilities, or because of poor general health. Employer will exclude those obviously at high risk. Person selection may also be influenced by person habits and physical conditions such as weight, smoking, or alcoholism. This effect will vary according to the labor situation, i.e. during period of labor shortages less fit workers could be included into the labor force whereas during periods of of labor surpluses employers can be much selective.