In-depth survey report: control of dust in a textile dyeing operation at Multicolor Industries, Inc., Brooklyn, New York, report no. CT-226-04.
Researchers from the National Institute for Occupational Safety and Health conducted an evaluation to determine the efficiency of three techniques for controlling workers' exposure to powdered dyes. These techniques were: 1) a down draft hood to move dust away from the employees' breathing zone; 2) the addition of a "de-dusting agent," typically a light oil, to the dye to reduce the dye's tendency to become and stay airborne; and 3) the size of the large containers used to ship and store the dyes. Two series of measurements were made under varying control conditions to quantify the inhalation exposure of a weigh-out operator to airborne dye dust. A Crompton and Knowls Azoanthrene Jet Black K Crude was used for the first series of measurements and a Dystar Remazol Red RB for the second. This "weigh-out" process, where the powders are scooped from open containers and dumped into smaller containers for weighing, is the time of greatest potential exposure to employees. In the first (February, 1999) series of tests, the use of ventilation was shown to significantly reduce the airborne dust exposure to the worker, producing an 88% decrease. Barrel size seemed marginally effective in reducing dust exposure. The use of small barrels produced an estimated reduction of 80% when high dustiness dye was used. The use of a de-dusted dye produced an estimated reduction of about 60% when large barrels were used. The corresponding estimate for small barrels indicated no reduction due to de-dusted dye. The second (September, 1999) series oftests confirmed the effectiveness of ventilation in reducing airborne dust levels, and also indicated that the de-dusted dye, used when the ventilation is off, significantly reduced airborne dye conC'entration by approximately 80%. This effect would have been greater but for the one sample (identified as R3 in the September results) which appears to be inconsistent with the others. However, no other justification can be developed for regarding this sample as an outlier. The small number of total tests and particularly the limited replication are considered to be the primary factor responsible for lack of statistical significance. It is recommended that additional tests be conducted to investigate the effects of the dye dustiness of drum size. Because the availability of a downdraft ventilation system such as was evaluated during this study is limited, this additional testing would be most appropriately conducted with no such ventilation system.