Relief and Social Services   Added source reference and updated   Pared away following details but kept the  figure in the text  Fewer than six percent of refugees qualify as hardship cases with the largest number being in Lebanon where restrictions on Palestinians entering the Lebanese job market cause severe hardship  Rations are distributed to families in UNRWAs special hardship category every quarter  Finances permitting the Agency also provides small cash grants to very poor refugee families to help with the purchase of items such as school uniforms and school books or as crisis grants for example if they lose all their possessions in a house fire  Most of the concreteblock shelters in the refugee camps were built by UNRWA in the s to replace the tents in which refugees had lived since the  war Others were built after the  conflict Although most refugees have been able to make improvements and additions to their shelters over the years the very poorest refugees often live in shelters that are now in extremely bad condition Wet crumbling walls leaking zinc roofs and rodent infestation cause additional social and health problems UNRWA has been able to repair hundreds of shelters in recent years often simply by supplying materials while the families provide their own labour UNRWA is unable to keep up with the growing numbers of special hardship case families who each year join its waiting list for shelter rehabilitation