Hammond-DR; Blade-LM; Shulman-SA; Zimmer-J; Cecala-AB; Joy-GJ; Lo-L-M; Chekan-GJ
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB-282-18a, 2011 Dec; :1-26
In 2010, NIOSH researchers and the Silica/Milling-Machines Partnership coordinated by the National Asphalt Pavement Association (NAPA), evaluated dust emission-control systems for five pavement-milling machines on State Highway 47 south of Bonduel, Wisconsin. To suppress dust, water spray controls were installed on all five milling machines and a local exhaust ventilation control was installed on one machine. The tests consisted of numerous, replicate short-term milling trials (nominally about 6 minutes each in duration). During a trial, a test milling machine removed approximately 3 inches of depth of the asphalt surface while operating either its existing production water-spray system (the "baseline configuration"), or one of its modified test emission-control configurations. During the trials, respirable-dust concentrations were measured at ten selected locations around each mill using continuous real-time data-logging dust monitors. The results from six key monitoring locations (from among the ten) together are considered to best represent dust-emission rates, because they surround the low-to-the-ground dust-generating areas of the machine where the modified emission controls are located. Trial-mean concentrations from these "lower-six" locations were averaged together to obtain a single lower-six-location average for that trial. The average lower-six result for the baseline dust-control configuration in a set was compared with that for each of the modified test configurations in that set. Dust-emission reductions were computed for each test configuration versus the baseline in that set. Average reductions across all sets for that machine were computed, along with their statistical confidence intervals. For the lower six sampling locations, statistically significant reduction in mean respirable dust concentrations of 81% and 69% occurred during testing of configurations D21 and D3 which were local exhaust ventilation configurations at medium and low fan speeds of approximately 1500 actual cubic feet per minute (acfm) and 1000 acfm of air. The reductions in mean respirable dust concentrations at the lower-six sampling locations were not statistically significant for any of the evaluated water spray configurations. For the operator bridge sampling location, statistically significant reductions in mean respirable dust concentrations of 77%, 65%, 59%, and 44% were measured during testing of configurations D21, D3, E23, and E22, respectively. No other evaluated configurations resulted in statistically significant reductions at the operator bridge. Based on the results from this and previous studies, the NIOSH researchers recommend additional testing of the wet drum design and optimization of local exhaust ventilation systems as the primary control method for reducing respirable crystalline silica during asphalt pavement milling.
Control-technology; Engineering-controls; Region-5; Construction; Ventilation; Ventilation-systems; Exhaust-ventilation; Laboratory-testing; Machine-operation; Milling-industry; Construction-equipment; Road-construction; Simulation-methods; Engineering; Equipment-design; Control-equipment; Control-systems; Dust-collection; Dust-control; Dust-control-equipment; Equipment-reliability; Performance-capability; Emission-sources; Testing-equipment; Qualitative-analysis; Quantitative-analysis; Gases; Analytical-instruments; Infrared-spectrophotometry; Vacuum-cleaning-systems; Vacuum-equipment; Testing-equipment
7631-86-9; 14808-60-7; 2551-62-4
Field Studies; Control Technology
NTIS Accession No.
National Institute for Occupational Safety and Health