When selecting the proper welding process for the task, evaluating the potential for fume generation and the availability of different, lower-fume welding processes may help lower your exposure to harmful compounds in welding fumes.
Hazard Analysis — Welding fumes
Workers who fabricate metal structures in shop and field may be exposed to welding fumes.
Welding and associated processes such as arc-cutting, are routinely performed by pipefitters, ironworkers, boilermakers and sheet metal workers; other trades may also weld and perform thermal cutting of metals. This work often occurs in tanks or boilers or in other poorly ventilated settings. The fume generated during welding contains fine particles composed of the constituents in the base metal, the electrodes, fluxes, and the filler rods; these particles can deposit in the lungs or enter the blood stream by passing through the lungs. Welding can also create hazardous gases (see Table 1 below). Construction workers can be exposed to the hazards of chromium and manganese; the exposure varies with the welding process and the specific metals used. Estimates of the number of workers exposed to welding fumes range from 410,000 full-time welders to over one million workers who weld intermittently.
The American Welding Society has identified over 80 different types of welding and allied processes in commercial use. Of these processes, some of the more common types include shielded manual metal arc welding, gas metal arc welding, flux-cored arc welding, gas tungsten arc welding, and others such as submerged arc welding, plasma arc welding, and oxygas welding.
The chemical properties of welding fumes can be quite complex. Most welding materials are alloy mixtures of metals characterized by different steels that may contain iron, manganese, silica, chromium, nickel, and others. Fumes are released from the base metal and from welding rods, and gases are produced from some of the arc welding processes; see table 1.
Table 1. Hazardous Byproducts of Welding
|FUME||GASES||RADIANT ENERGY||OTHER HAZARDS|
|Chromium III & VI||Nitrogen Oxide||Infrared||Vibration|
There are a number of health effects caused by exposure to welding fume, including:
- metal fume fever
- COPD/bronchitis and asthma
- lung cancer
- neurological injury from manganese, like Parkinson’s disease
One study, “A case-control study of airways obstruction among construction workers”, examined occupational exposures to vapors, gases, dusts and fumes (VGDF) among older construction workers between 1997 and 2013, comparing 834 workers with COPD and 1,243 controls. Approximately 18% (95% CI=2-24%) of COPD in this population can be attributed to workplace exposures associated with construction tasks. After adjusting for smoking habits in this population, the study also revealed among construction workers who never smoked, 32% (95% CI=6-42%) of COPD was attributable to the workplace.
Parkinson-like disease: Manganese is a component of nearly all steels and is present in many welding rods and wires. Manganese has been known to cause neurological injury for many years. The first cases were reported in 1837. A paper in 1955 on manganese poisoning among miners described “manganese madness” with mood swings followed by the development of tremor, abnormal gait, and other symptoms akin to Parkinsonism.
Level of Risk:
Risk for lung cancer: The Occupational Safety And Health Administration estimates that there are almost 200,000 construction workers exposed to chromium, and that a substantial proportion of these workers are exposed above the current OSHA PEL. The current OSHA PEL of 5 ug/m3 still leaves exposed workers with a significant risk of lung cancer, and the National Institute for Occupational Safety and Health recommends a lower exposure level of 1 ug/m3.
Table 2 Exposure to Cr (VI) Hexavalent Chromium in Construction
|TASK||Total Exposed||% Exposed >1 mg/m3 (NIOSH REL)||% Exposed > 5mg/m3 (OSHA PEL)|
|Stainless steel welding||60,449||41.9%||26.7%|
|Carbon Steel Welding||80,404||18.0%||6.0%|
Risk for Parkinson-like disease: Numerous studies indicate that welders may be at increased risk of neurological and neurobehavioral health effects when exposed to metals such as lead, iron and manganese. Some studies indicate that welders exposed to low levels of manganese (<0.2 mg/m3 ) perform more poorly on tests of brain function and motor skills. These effects include changes in mood and short-term memory, altered reaction time, and reduced hand-eye coordination. It is not known if these findings have clinical significance. The current OSHA permissible exposure limit (PEL) is 5 mg/m3 for a ceiling level. The recommended NIOSH recommended exposure level (REL) is 1 mg/m3 for an 8 hour time weighted average (TWA) and 3 mg/m3as a short term exposure limit. Health effects have been reported at exposure levels lower than both the OSHA PEL and the NIOSH REL.
More information is available at the NIOSH web site: http://www.cdc.gov/niosh/topics/welding/
CPWR Construction Chart Book, 4th Ed. CPWR-The Center for Construction Research and Training. Silver Spring, MD. March 2008.
Occupational Safety and Health Adminisration, Department of Labor. February 28, 2006. Federal Register, 71(39), Rules and Regulations, Table VIII-2.
Pam Susi, Mark Goldberg, Pat Barnes, and Erich (Pete) Stafford. 2000. The Use of a Task-Based Exposure Assessment Model (T-Beam) for Assessment of Metal Fume Exposures During Welding and Thermal Cutting. Applied Occupational and Environmental Hygiene, 15(1); 26-38.
Bowler RM, Roels HA, Nakagawa S, Drezgic M, Diamond E, Park R, Koller W, Bowler RP, Mergler D, Bouchard M, Smith D, Gwiazda R, Doty RL. Dose-effect relationships between manganese exposure and neurological, neuropsychological and pulmonary function in confined space bridge welders. Occup Environ Med. 2007 Mar;64(3):167-77.
Santamaria AB, Cushing CA, Antonini JM, Finley BL, Mowat FS. State-of-the-science review: Does manganese exposure during welding pose a neurological risk? J Toxicol Environ Health B Crit Rev. 2007 Nov-Dec;10(6):417-65.
Blanc PD, Torén K. Occupation in chronic obstructive pulmonary disease and chronic bronchitis: an
update. Int J Tuberc Lung Dis. 2007 Mar;11(3):251-7.
Sørensen AR, Thulstrup AM, Hansen J, Ramlau-Hansen CH, Meersohn A, Skytthe A, Bonde JP. Risk of lung cancer according to mild steel and stainless steel welding. Scand J Work Environ Health. 2007 Oct;33(5):379-86.
The hazards posed by welding are dependent on the materials (e.g. base metal, electrodes and filler metals, shielding gases, etc); the welding process; and environmental conditions, such as the degree of enclosure or whether or not effective ventilation is in place. Personal air monitoring of workers conducted under the supervision of a professional industrial hygienist is used to determine whether exposure levels pose a health risk and are below legal and recommended exposure limits.
(Note) A professional industrial hygienist is a person possessing either a baccalaureate degree in engineering, chemistry, or physics or a baccalaureate degree in a closely related biological or physical science from an accredited college or university, who also has a minimum of three years of industrial hygiene experience. For more detail visit: http://www.aiha.org/Content/AboutAIHA/whatisIH.htm.
The type and magnitude of exposure will depend on the materials being welded. Stainless steel welding may generate nickel and hexavalent chromium and if stainless welding is performed with Sheilded Metal Arc Welding (SMAW) w/ Flux Cone Arc Welding (FCAW) the flux generates manganese as well. Mild steels generate manganese. Torch-cutting or welding through coated steels may generate organic vapors or fumes generated from coatings (such as lead in the case of lead painted steel). Stick (or shielded metal arc) and flux core welding typically generate the most fume and TIG welding the least.
Welding carbon steel does not necessarily produce Mn in the fume. Almost all of the Mn comes from the flux in FCAW and SMAW consumables. Gas Metal Arc Welding (GTAW) (TIG) does not use flux and one would not find Mn in that fume when used for welding carbon steel. SMAW and FCAW are the most common welding processes used on carbon steel and those processes on that metal are the primary sources of Mn over exposure in welders.
Material Safety Data Sheets (MSDS) should provide information on the hazardous components of steels, electrodes and filler metals, however, this information is not always accurate. Because of the very high temperatures associated with welding, metals containing relatively low percentages of metals (such as nickel, Hexavalent chromium and manganese) can generate hazardous levels of fume. Personal air monitoring methods used to assess welding fumes vary depending on the specific hazardous agent being addresses. Both OSHA and NIOSH publish sampling methods for specific hazardous agents such as total particulate, Hexavalent chromium and other metals including manganese and nickel.
NIOSH Manual of Analytical Methods: http://www.cdc.gov/niosh/nmam
US Department of Labor Sampling and Analytical Methods: http://www.osha.gov/dts/sltc/methods/index.html
Regulations & Standards:
Regulations adopted by a state must be at least as protective as the corresponding federal standard. Work may also be subject to rules of other federal, state and local agencies. Even where there is no hazard specific standard, OSHA prohibits employers from to work in surroundings or under working conditions which are unsanitary, hazardous, or dangerous to his health or safety.
Occupational Exposure Limit
1 mg/m3 (TWA) and 3 mg/m3 (STEL)
5 mg/m3 (ceiling)
REL: recommended exposure limit
STEL: short-term exposure limit
TLV: threshold limit value
TWA: time-weighted average
Federal OSHA Standards are enforced by the U.S. Department of Labor in 26 states. There are currently 22 states and jurisdictions operating complete State plans (covering both the private sector and state and local government employees) and 5 - Connecticut, Illinois, New Jersey, New York and the Virgin Islands - which cover public employees only. If you are working in one of those states or jurisdictions you should ensure that you are complying with their requirements.
BIM is a concept that offers software application to integrate building information for hazard identification and safety planning.