Manganese and Welding Fume Exposure and Control in Construction

Abstract

Overexposure to welding fume constituents, particularly manganese, is of concern in the construction industry due to the prevalence of welding and the scarcity of engineering controls. The control effectiveness of a commercially available portable local exhaust ventilation (LEV) unit was assessed. It consisted of a portable vacuum and a small bell-shaped hood connected by a flexible 2 inch (50.8 mm) diameter hose, in both experimental and field settings. The experimental testing was done in a semienclosed booth at a pipefitter training facility. Five paired trials of LEV control vs. no control, each approximately 1 hr in duration and conducted during two successive welds of 6 inch (152.4 mm) diameter carbon steel pipe were run in random order. Breathing zone samples were collected outside the welding hood during each trial. In the field scenario, full-shift breathing zone samples were collected from two pipefitters welding carbon steel pipe for a chiller installation on a commercial construction project. Eight days of full-shift sampling were conducted on both workers (n = 16), and the LEV was used by one of the two workers on an alternating basis for 7 of the days. All samples were collected with personal sample pumps calibrated at 2 L/min. Filter cassettes were analyzed for total particulate and manganese concentration by a certified laboratory. In the experimental setting, use of the portable LEV resulted in a 75% reduction in manganese exposure (mean 13 μg/m ³ vs. 51 μ g/m ³ ; p < 0.05) and a 60% reduction in total particulate (mean 0.74 mg/m ³ vs. 1.83 mg/m ³ ; p < 0.05). In the field setting, LEV use resulted in a 53% reduction in manganese exposure (geometric mean 46 μ g/m ³ vs. 97 μ g/m ³ ; p < 0.05) but only a 10% reduction in total particulate (geometric mean 4.5 mg/m ³ vs. 5.0 mg/m ³ ; p > 0.05). These results demonstrate that LEV use can reduce manganese exposure associated with welding tasks in construction.

Keywords:

• construction
• exposure control
• local exhaust ventilation
• manganese
• welding

ACKNOWLEDGMENTS

This work was made possible by a grant from the National Institute for Occupational Safety and Health.

The authors wish to acknowledge the contribution of the following who provided information on welding practices and materials commonly used by the trades they represent: Gary Batykefer, Sheet Metal Occupational Health Institute; David Haggerty, Mobilization, Optimization, Stabilization, and Training (MOST) Fund-International Brotherhood of Boilermakers, Iron Ship Builders, Blacksmiths, Forgers and Helpers (IBB); Frank Migliaccio, International Association of Bridge, Structural, Ornamental and Reinforcing Ironworkers; Travis Parsons, Laborer's Health and Safety Fund of North America; Milan Racic, IBB; William Rhoten, United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry of the U.S. and Canada (UA).

We also recognize the following members and staff of UA 120 in Cleveland, Ohio, who helped conduct the experimental evaluation: Terry Urbanek, Dave Feldscher, and Fred Webber. For assistance gaining site access for the field evaluation we thank Jim Kennedy, Facilities Manager for the University of Michigan School of Public Health, and Ron House and Bryce Mitchell, UA 190 representatives in Ann Arbor, Mich. Dave Feldscher and Christopher Cole, LMG Inc., assisted in air monitoring in both experimental and field settings, and Ryann Fisher assisted with literature review.

Finally, we wish to acknowledge the welders who participated in the evaluation and provided valuable input regarding the successful use of portable ventilation for construction welding operations.

The contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institute for Occupational Safety and Health.