NIOSH warns that workers may be risking their lives when working in trenches or near potentially unstable ground. At least six workers have died this year in cave ins and an average of 60 workers die in these situations every year. In most cases these deaths could have been prevented if existing safety standards had been met. The deaths of six workers involved in cave ins during construction work were described. These included: a 35 year old man building a manhole in a 10 foot deep sewer trench without the safety of a steel trench box; a 68 year old man buried when the unshored walls of a 16 foot by 4 foot ditch collapsed; a 62 year old man buried when a 40 foot long section of a dirt embankment collapsed; a 51 year old foreman asphyxiated when the unfortified walls of a ditch caved in; a 34 year old man killed when two concrete slabs and 6 feet of dirt buried him while he was repairing a sewer line; and a 29 year old man who was standing on the edge of a 7 foot deep trench when it gave way. Precautions which should be taken when working with trenches include using a shield or trench box system, shoring sides of excavations, sloping the sides of excavations, or securing sides by equivalent means such as bracing.