Lead, chromium, and cadmium emission factors during abrasive blasting operations by bridge painters

Work space airborne concentrations of lead, chromium, and cadmium were measured during abrasive blasting by bridge painters for the determination of emission rates. The operation used compressed air to blast steel grit at steel or metal surfaces, removing lead-based paint. It was enclosed with plastic tarpaulins to prevent the release of lead- and chromium-laden dust. Consequently, workers were at increased risk from exposure by inhalation or ingestion. Area samples were collected in 13 contained work areas on a 4-leaf bridge and adjacent viaduct while blasting was performed. Enclosure volume and exhaust air flow rate were measured for each containment area. Work space airborne concentrations ranged from 196-31,410 micrograms/m3 for lead, 1-657 micrograms/m3 for chromium, and 1-19 micrograms/m3 for cadmium. Mass balance models were used to calculate emission rates and emission factors using the measured area concentrations. Average emission factors on the bridge were 20,400 mg/m2 for lead, 75 mg/m2 for chromium, and 16 mg/m2 for cadmium; and on the viaduct were 8790 mg/m2 for lead, 568 mg/m2 for chromium, and 2.0 mg/m2 for cadmium. These values were validated using estimates of total paint volume and composition on the structure and total waste generation. All estimates were within 50% of each other except chromium estimates for the bridge. The emission factors allow prediction of work space airborne concentrations during similar operations and are a first step in the design and implementation of control measures.