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pH Increase Observed in Exhaled Breath Condensate from Welding Fume Exposure

Boyce, Paul D. MD, MPH; Kim, Jee Young SD; Weissman, David N. MD; Hunt, John MD; Christiani, David C. MD, MPH

Journal of Occupational and Environmental Medicine: April 2006 - Volume 48 - Issue 4 - p 353-356
doi: 10.1097/01.jom.0000205988.50907.d8
Original Articles

Objectives: We sought to investigate changes in exhaled breath condensate (EBC) pH in healthy workers exposed to welding fumes.

Methods: Fourteen exposed participants (median age 39 years, 5 smokers) and 8 nonexposed controls (median age 44 years, 1 smoker) were monitored at an apprentice welding school. Exposure to fine particulate matter less than 2.5 μm (PM2.5) was assessed using cyclone samplers. EBC samples were collected at baseline and at the end of the work shift. EBC samples were deaerated using argon and pH values were measured using standard pH microelectrodes.

Results: Mean ± SEM PM2.5 levels were 1.17 ± 0.18 mg/m3 for exposed subjects and 0.03 ± 0.01 mg/m3 for controls. Baseline median (range) EBC pH values for the control and exposed group were similar (P = 0.86), 7.21 (4.91 to 8.26), and 7.39 (4.85 to 7.79), respectively. The exposed subjects had a small-but-marginally significant (P = 0.07) pre- to post-work shift increase in pH of 0.28, whereas the control group showed a minimal increase of only 0.03 (P = 0.56). Compared with the control group, the exposed group had a median cross-shift pH increase of 0.25 (P = 0.49).

Conclusions: The aerosolized fine particulate matter contained in metal fumes may be associated with an acute increase in EBC pH values. Further study is necessary to investigate the acute rise in EBC pH after acute exposure to welding fume.

From the Department of Environmental Health, Occupational Health Program, Harvard School of Public Health, Boston, Massachusetts (Drs Boyce, Christiani, Kim); Pulmonary and Critical Care Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts (Drs Boyce, Christiani); National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina (Dr Kim); Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV (Dr Weissman); and Division of Pediatric Respiratory Medicine, University of Virginia, Charlottesville, Virginia (Dr Hunt).

Paul Boyce has no commercial interest related to this research.

The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.

Address correspondence to: Paul D. Boyce, Department of Environmental Health, Occupational Health Program, Harvard School of Public Health, Boston, MA 02115. E-mail:

©2006The American College of Occupational and Environmental Medicine