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Control of Welding Fume Exposures in Shipbuilding Confined Spaces.

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Presentation on theme: "Control of Welding Fume Exposures in Shipbuilding Confined Spaces."— Presentation transcript:

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  Develop training concepts  Validation of training concepts  Develop training program  Pre-intervention assessment  Post intervention change  Directions for future STUDY OVERVIEW

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  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 TRAINING CONCEPTS

7 ventilation training: Basic Ventilation Concepts

8 ventilation training: Practical Questions

9 Minifan-induced crossdraft CROSS DRAFT AND MIXING

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  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 INTERVENTION ASSESSMENT

15 ventilation training About 100 workers participated in the ventilation training program at Vigor in 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 RESULTS CHANGE IN SCORE ~ 1 MONTH POST TRAINING n Post-Pre improvement SE Worthwhile setting up for short job 710.110.13 Too much work for any length job. 700.170.14 Takes too much time to set up 6900.13 Confidence in my ability to decide what vent works best 700.170.1 Confidence in my ability to set up ventilation 710.10.83 Properly used vents can reduce my exposure 71-0.010.08 Properly used vents will increase the comfort and visibility 71-0.280.09 Properly used vents will reduce exposures of others 71-0.030.07 Mean score based on a 1 to 5 scale

18 Pre-training % correct Post-training % correct Change in % correct You may need a respirator even when using vents100 0 When exhausting the length of duct does not matter8685 Weld quality is always reduced if air is moving past you7869-9 Welding smoke is heavy and settles72753 The number of blowers needed depends on number of welders697910** How many blowers are needed to ventilate 9x9x9 ft space?567115** Which of the images shows short-circuiting?2218-4 Which type of exhaust ventilation is practical and effective?25349 What advantage does blowing have over exhausting?6056-4 QUESTIONNAIRE RESULTS CHANGE IN % CORRECT ~ 1 MONTH POST TRAINING ** McNemar’s test of proportions, p<0.05

19  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 STUDY RESULTS AND CONCLUSION

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:  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, Hendrika Meischke, 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  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/m 3 8-hour TWA PEL: Overall: 82% Confined spaces: 94% Enclosed spaces: 70% Spaces with dilution ventilation: 31% Spaces with local exhaust ventilation: 100% a preliminary study in other shipyards showed:

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