Objectives
HAC Industries, a speed towboat manufacturing plant requested assistance from Aero-Environmental Consulting in controlling worker exposures to styrene at a plant that produces fiber-reinforced speed towboats. The plant requested Aero-Environmental assistance because previous air sampling conducted by the Cal/OSHA and The Hartford Insurance indicated concerns about elevated styrene concentrations in the lamination area of this production facility. Aero-Environmental, Certified Industrial Hygienist, Jorge Vizcaino, CIH 9814 conducted a site visit and collected personal breathing zone and area air samples while workers performed the manufacturing tasks of lamination of the towboats.
Methods
All samples were collected during the course of normal employee work activities and analyzed for styrene using NIOSH Method 1501. All sampling conducted was full-shift sampling since full-shift sampling from a prior California Occupational Safety and Health Administration (Cal/OSHA) compliance inspection showed one (1) employee exposure to styrene above the Cal/OSHA permissible exposure limit. During this Cal/OSHA initial site visit, 6 personal breathing zone and 1 area air samples were collected while workers performed tasks of Lamination and Pull/Grinding in the Lamination, Pull/Grinding, and Gel Coat Departments of Building 485. After the initial site visit, the company made changes to the Spray resin/fiberglass system (according to Mr. Joe Hart) that reduced exposures to the spray resin and made the application process more efficient. In addition, according to John Doe, CEO, several engineering and administrative controls have been implemented including increased dilution ventilation (exhaust), administrative controls (mandatory breaks), and implementation of Respiratory Protection Program (RPP) and proper respiratory usage. The ventilation according. To Rick Lee is now up to 8,700 cubic feet per minute. During this follow-up site visit conducted by Aero-Environmental, 4 personal breathing zone and 2 area air samples were collected from workers performing the lamination tasks and in the lamination area.
Results
During the initial Cal/OSHA site visit, the geometric means of the personal breathing zone styrene air samples were 59 parts per million (ppm). (n = 4) for workers performing the Lamination task, where n is the number of workers sampled for a given mean result. The geometric mean of the personal breathing zone styrene air samples from the lamination tasks measured during this follow-up site visit conducted by Aero-Environmental was 22 ppm. (n = 4). The 8 hr Time Weighted Average (TWA) for one employee (Sergio Villanueva) was 33 ppm and 44 ppm for a second employee (Jose Zaragoza).
Conclusions
Engineering changes made to the spray resin fiberglass system, ventilation system, and administrative controls have been effective at controlling worker exposures to styrene. Personal breathing zone styrene air samples were below the Cal/OSHA Permissible Exposure Limit (PEL) of 50 ppm. It appeare that the additional local/exhaust ventilation changes, and work/shift rotations to eliminate styrene exposure during the lamination process, has been effective in reducing TWA exposures to employees in the lamination area to below 50 ppm.
Engineering and Administrative Changes
The following engineering and administrative controls have been implemented in the lamination/gel coat areas of Building 485:
- A complete maintenance overhaul of the air exchange system. Air is now exchanged every six minutes.
- No open containers in this area.
- An administrative analysis of labor cycles and ensuring policies that minimize exposure.
- Changes in equipment
- Implementation of an on-going maintenance cycle every six months.
CONCLUSIONS
Initial site visit-Cal/OSHA
The gel-coating and pull/grind tasks were very effective at controlling worker exposures to styrene as demonstrated by the air samples collected during the initial site visits. Air sampling results from the lamination tasks indicated that control measures were needed to reduce styrene concentrations.
During the initial site visit, the plant was using respiratory protection to reduce average styrene exposures of workers during the lamination task but inadequate respirator usage was observed by Cal/OSHA personnel.
Follow-up site visit
At the time of the follow-up evaluation conducted by Aero-Environmental, some design changes were made to the spray rack resin application system, as well as drastic engineering and administrative controls. These changes were very important according to Joe Hart since they could potentially reduce exposures to styrene for workers in the lamination area. These changes to the lamination process, engineering controls, and administrative controls did indeed reduce worker exposures to styrene. Aero-Environmental recommends the continued use of organic vapor charcoal filter respirators for workers performing the lamination tasks and all workers using respirators should strictly follow OSHA's Respiratory Protection Program 1910.134.
Administrative controls requiring workers to leave the room and take a break every 2 hours or after the lamination was finished have been effective at reducing styrene exposures. Administrative control efforts should continue and all workers in the lamination area should continue to leave the room to take advantage of the administrative control.
The TWA sampling approach was effective in identifying that engineering, administrative, and Personal Protective Equipment (PPE) controls have been effective in reducing styrene concentrations during lamination tasks.
Jorge Vizcaino, MA, CIH, REA, CMC, CAC, CDPH, is a Certified Asbestos Consultant (CAC) and Certified Industrial Hygienist (CIH). He has over 15 years of experience in Industrial Hygiene Safety, Hazardous Material Assessments, Indoor Air Quality. He is an active member of the American Industrial Hygiene Association.
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