Control of Welding F ume E xposures in S hipbuilding Confined Spaces

1. Control of Welding Fume Exposures in Shipbuilding Confined Spaces

2. purpose of the study To develop and assess a ventilation training program to reduce welding exposures in confined spaces. To determine if training welders can change ventilation practices.

3. Motivation: excessive exposures to welding fume • welding fume • ultrafine particles • hazardous components • metals, gases, particulate matter • health risks: • respiratory • lung disease (COPD, Asthma) • “metal fume fever” (galvanized) • Cancer (SS) • cardiovascular diseases

4. Study Overview • Develop training concepts • Validation of training concepts • Develop training program • Pre-intervention assessment • Post intervention change • Directions for future

5. Ventilation “lab” tests • After observations in shipyards, we used a more controlled space to test which parameters had the most effect on fume control, such as: • Duct height • Duct proximity • Air flow • Room mixing This helped us develop ventilation training guidelines.

6. Training concepts • Simple, pictorial • Box model • Exhaust placement • Local, General • New concept: Regional Exhaust Ventilation • Mixing • Exhaust vs. Supply • Cross draft • “Mini-fan” • Common problems • Short circuiting • Dead space

7. ventilation training: Basic Ventilation Concepts

8. ventilation training: Practical Questions

9. Cross Draft and Mixing Minifan-induced crossdraft

10. ventilation training: Short circuit

11. ventilation training Common Problems

12. verifying our recommendations We tested our recommendations by monitoring the fume exposure by measuring exposure before and after adjustments. Exhaust at floor: Poor control Exhaust high: Good Control

13. verifying our training principles Simple ventilation adjustments reduce worker’s exposure

14. Intervention Assessment • Pre-Assessment • Questionnaire on trainees • Monitoring in typical conditions • Training • In groups of up to 20 at a time • Primarily new construction at Vigor and Dakota Creek • Post-Assessment • Questionnaire on same trainees • Monitoring in typical conditions

15. ventilation training About 100 workers participated in the ventilation training program at Vigorin Seattle and Dakota Creek, in Anacortes. • Five sessions with about 20 people • Combination of discussion, lecture, and ventilation problem-solving exercises • Training was led by an industrial hygienist with a background in designing temporary ventilation for welding in similar situations in refineries. Participants filled out a survey about their knowledge and use of ventilation before the class and again several weeks later.

16. Observed conditions and welding fume exposure levels

17. Questionnaire ResultsChange in Score ~ 1 Month Post Training Mean score based on a 1 to 5 scale

18. Questionnaire resultsChange in % Correct ~ 1 Month post training ** McNemar’s test of proportions, p<0.05

19. Study results and conclusion • Shipyard environment is very challenging • For environmental control • For conducting research • Ventilation CAN be set up in confined spaces to significantly reduce exposure to welders • Sufficient fresh air supply • Strategically placed for fume removal • Dissipation where appropriate • But it is not being effectively used in many conditions • A single training for welders is NOT sufficient to change practices • Many barriers and organizational constraints which training alone cannot overcome

20. Recommendations • Continue to develop expertise within welding and support trades to increase effectiveness of ventilation • Develop system to identify adequacy of ventilation during work • Continue supporting use of respirators as needed

21. Next steps: • Further analysis • Dissemination of results and training materials through: • Scientific journals • Research group website: https://blogs.uw.edu/uwseixas/ • Suggestions for additional dissemination? • THANK YOU! • We greatly appreciate the participation and support from: • Puget Sound Shipbuilders Association • Vigor Shipyards • Dakota Creek • Foss Maritime • Lake Union Dry Dock • Contributors: • Faculty: Noah Seixas, HendrikaMeischke, Mike Yost, Lianne Sheppard • Staff: Chris Warner, Rick Neitzel, Marc Beaudreau, Bert Stover, Gerry Croteau • Students: Jane Pouzou, Jeff Walls, Lea Duffin, Eddie Kasner

22. air monitoring and observations We measured how well different ventilation setups worked in real situations by observing and monitoring the fume levels in the spaces where welders were working. Hundreds of assessments of ventilation were made at Vigor, Dakota Creek, Foss, and Lake Union Dry Dock.

23. common ventilation problems • “Short-circuiting” of the air • Excessive bends or kinks in duct • Inadequate equipment for space and amount of welding (many spaces that needed multiple blowers only had one) • Poor placement of the duct • Too far from the fume • Too low to the ground

24. a preliminary study in other shipyards showed: • Use of ventilation: • 3% used local exhaust ventilation • 29% used dilution ventilation (either exhaust or supply) • 68% did not use LEV or DV • Use of a respirator: 41% • Exceedance of the 5 mg/m38-hour TWA PEL: • Overall: 82% • Confined spaces: 94% • Enclosed spaces: 70% • Spaces with dilution ventilation: 31% • Spaces with local exhaust ventilation: 100%