Airborne Lead, Dust, and Asbestos-like Fibers in Mechanical Street Cleaner Environments and an Evaluation of Some Contributory Factors

Abstract

Exposures of mechanical street sweeper operators to lead, asbestos, and dust were determined, and an evaluation of the factors contributing to the level of exposure was conducted. Factors evaluated included rain, frequency of sweeping, traffic volume, and age of the dwellings in the sweeping areas. Sampling was conducted during the months of July through September. Sweeping routes were categorized according to building age and were sampled under rain and no rain conditions. Sweeping frequency and traffic volumes were addressed retrospectively.

Twenty-nine samples were collected. Total dust concentrations ranged from 0.26 to 3.55 mg/m³ (mean, 2.09 mg/m³). Lead concentrations ranged from 0.99 to 6.64 μg/m³ (mean, 3.16 μg/m³) and were higher than ambient levels measured by the local air pollution control agency (0.41–0.80 μg/m³). The range of lead concentrations in the street sweepings was 324–3228 μg/g (mean, 1700 μg/g). Lead concentrations in the airborne dust ranged from 400 to 5000 μg/g with a mean of 1838 μg/g. Total fibers ranged from < 0.005 to 0.024 fibers/cc.

Multiple regression analysis indicated that rain, building age, and sweeping frequency interacted to affect the concentrations of dust in the air. Rain appeared to be the strongest factor. Rain and housing were the factors with the strongest influence on total fiber concentration. All values of dust concentration, lead concentration, and total fibers were below the Occupational Safety and Health Administration Permissible Exposure Levels (PELs). The data supported a positive correlation between dust concentration and lead concentration. The factors of rain, age of structure, sweeping frequency, and traffic volume did not appear to influence the levels of lead found in the air, dust, or dirt. Based on the results of this study, it is recommended that street cleaner cabs be equipped with air cleaning systems. Specially designed window panels can be installed to allow the operator to have a direct view downward of the pavement area. The data provided by this study can be applied by industrial hygienists in assessing exposures of workers employed in the expanding residential and soil lead abatement industry, particularly where lead-contaminated dust and dirt must be removed from paved areas adjacent to abatement areas.