Ventilated containment structures for protecting workers from exposure to lead (7439921) containing dusts while performing maintenance on steel structures coated with lead based paint were evaluated. The structures, designed by NIOSH, consisted of a containment system around a process tank at an oil refinery, and two containment structures at a bridge, where workers used abrasive blasting to remove old paint. At the oil refinery, a nylon reinforced polyethylene enclosure enclosed an aluminum scaffolding around the process tank. Exhaust ventilation was through three high efficiency air filters using pneumatic blowers. At the bridge site, the first containment structure was made of interconnected canvas tarps suspended from the top of the roadway down to the ground with an exposure volume of 5,600 cubic meters (m3). Ventilation was with two exhaust ducts suspended from a street light pole with no air supply inlets. The second containment was a 85m3 enclosure made of an alloy piping frame, rigid corrugated polycarbonate side panels, and an aluminum grate floor suspended from two adjacent I-beams under the bridge. Ventilation was through a supply air fan at one end and an exhaust duct and fan at the other. Workers in all three structures wore continuous flow loose fitted hood respirators. During blasting in the three structures the personal lead exposures ranged from 6,200 to 22,000 micrograms (microg) per m3 and area air lead exposures ranged from 10,000 to 15,000microg/m3. Lead concentrations inside the enclosures decreased rapidly after blasting. Area lead exposures measured outside the oil refinery structure and the large and small bridge enclosures averaged 1, 210, and 18microg/m3, respectively. The author concludes that general ventilation alone cannot effectively control airborne lead exposures generated during abrasive blasting of steel structures painted with lead based paint.