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Environmental Informatics Archives

ISSN 1811-0231 / ISEIS Publication Series Number P002

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  Paper EIA06-021, Volume 4 (2006), Pages 244-261 = complimentary

Emission Factors Development for the Control of Lead and other Metals during Bridge Paint Removal

E. A. Iyiegbuniwe1, L. M. Conroy2 and P. Scheff2

1. Western Kentucky University, Department of Public Health, College of Health and Human Services, Bowling Green, KY.

2. University of Illinois at Chicago, Environmental and Occupational Health Sciences, School of Public Health, Chicago, IL. *Corresponding author: .

 

Abstract

A large number of bridges in the United States are in deteriorating condition and need repainting. Repainting requires the initial removal of old lead-based paint from affected bridges and other steel structures. A number of studies have documented increased risk of exposures and potential environmental pollution of surrounding areas during bridge paint removal. This study was conducted to evaluate emission rates and emission factors for lead, cadmium, chromium, and iron during abrasive blasting and power tooling operations on two bridges in the Midwestern United States. Emission factors modeling is useful in controlling process emissions through engineering controls since the results depend largely on process variables and therefore allows for the extrapolation of emissions from one process to another related process. Area samples were collected on 37-mm cellulose ester filters inside the bridge containments for the two construction activities. Lead concentrations ranged from 8038 to 22,990 μg/m3 (15,530 μg/m3 average) for abrasive blasting, and from 4.1 to 350 μg/m3 (82.04 μg/m3 average) for power tooling. Concentrations of iron ranged from 223,240 to 291,960 μg/m3 (250,330 μg/m3 average) for abrasive blasting, and from 6.83 to 675 μg/m3 (126 μg/m3 average) for power tooling. In comparison, cadmium and chromium concentrations were much lower than those reported for lead and iron. Inside containment average emission rates were 107, 0.01, 1.27, and 1,725 mg/s for lead, cadmium, chromium, and iron respectively, for abrasive blasting. The average emission rates for power tooling were 2.45, 0.029, 0.01, and 3.78 μg/s in the same order. The average emission factors for abrasive blasting were 34,000, 2.92, 350, and 515,840 mg/m2 for lead, cadmium, chromium, and iron, respectively. Analysis for power tooling using total airborne emissions generated inside the containment yielded 10.1, 0.12, 0.01, and 15.5 mg/m2 for lead, cadmium, chromium, and iron respectively. The total component mass on the surface of the bridge during abrasive blasting was 8,090 g for lead, 0.70 g for cadmium, 83.3 g for chromium, and 122,800 g for iron while the total mass of contaminant collected was 803 g for lead, 0.46 g for cadmium, 3.25 g for chromium, and 196.3 g for iron during power tooling. The average containment efficiencies for lead and iron measured during abrasive blasting were 91% and 95%, respectively. The average collector efficiency for the vacuum extractor obtained for the individual metals during power tooling was above 99.9%. The emission factors determined in this study are necessary to effectively design a general ventilation system or choose appropriate respiratory protection. Although several studies have documented high lead exposures during construction activities, only a few of them have calculated emission rates and emission factors. Additionally, most studies have focused on lead exposure, while this study presents area concentrations, emission rates, and emission factors for other metals of public health concern. In conclusion, power tooling was shown to be a better environmental engineering design than abrasive blasting, for the control of exposures to chemical hazards in this group of construction workers.


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