TITLE:	ES&H Manual
DOCUMENT ID:	6122 Appendix T4 Respiratory Health Effects Due to Inhalation of Fumes from Welding and Brazing

1.0 Exposure Assessment Requirements for Chemical Exposure through Inhalation Route

Examples of potential exposure to chemicals while welding include exposure to welding fumes, welding gases, decomposition gases, and decomposition products of the welding consumables:

· Fumes are fine, solid particles. Fumes can be formed as a result of welding operations.

· Gases may be produced in certain welding processes in the following ways:

o Decomposition of flux or electrode coatings and base metal coatings such as paints and solvents.

o Reaction products of the shielding gases.

o Oxidation of elements present in the arc or flame.

o Photochemical reaction of atmospheric gases due to ultraviolet radiation from the arc or flame.

· The electrode coating is a complex mixture of various components such as:

o Molding Agents (aluminum and magnesium silicate)

o Extruding Agents (alginates, starch, glucose and methyl cellulose)

o Binders (potassium and sodium silicates)

o Strengthening Agents (mostly mica which has replaced asbestos)

o Slag Formers (carbonates, silicates, oxides-rutile (TiO2) and fluorides)

o Metal Powders (e.g., iron) to act as alloying additions, to increase deposition rate or act as deoxidants

o Shielding Gas Formers (cellulose, calcium carbonate)

o Fluxing Agents (fluorspar, calcium carbonate and sodium silicate)

The welder must avoid the breathing the welding fume: In order to control exposure, local or general exhaust ventilation must be provided during welding to maintain concentrations of toxic materials within acceptable limits. The table lists examples of potential respiratory hazards associated with welding:

Substance	Source	Potential Health Effects
FUMES
Cadmium	welding or cutting of metal coated with cadmium some brazing pastes contain cadmium	acute irritation of the respiratory passages, delayed pulmonary edema; lung and kidney damage
Chromium	use of chrome-plated, or stainless steels or of hard-facing and chrome alloy electrodes	some forms of chromium have been found to be carcinogenic; other forms are biologically inert
Cobalt	welding or cutting of certain alloys	shortness of breath, inflammation of the lungs
Fluorides	certain fluxes contain fluoride and can give rise to dust, fume and vapor	irritation of eyes, throat, respiratory tract and skin; long-term exposure can lead to bone hardening
Iron	welding or cutting of ferrous materials	siderosis (temporary): inflammation of the lung due to iron deposition
Lead	welding or cutting of metal coated with lead or lead-based paints	central nervous system & gastro-intestinal effects
Manganese	use of manganese-containing electrode cores, coatings or wire; welding of manganese steel	metal fume fever, nervous system
Molybdenum	welding or cutting of molybdenum-containing alloys	bronchial irritation, liver and kidney changes
Nickel	welding and cutting of nickel-plated and stainless steels	irritation of respiratory tract; potentially carcinogenic
Silica (and silicates)	certain fluxes or dirt contamination could cause silica fume emissions	amorphous and not regarded as harmful
Vanadium	use of certain filler wires and special alloy steels	eye and respiratory tract irritation; chemical pneumonia
Zinc	welding or cutting of galvanized steel	metal fume fever
Other Metals	welding may produce fumes of other metals such as aluminum, copper, magnesium, tin, titanium and tungsten	no known serious health disorders are known to be due exposure to these fumes
GASES
Oxides of Nitrogen	formed by the direct combination of oxygen and nitrogen in the air surrounding the arc or flame	not a problem in outdoor or open shop welding; in confined spaces can build up to levels that can cause respiratory irritation or delayed pulmonary edema
Ozone	formed by certain welding operations, particularly when high amperages are involved, by the action of ultraviolet radiation on oxygen in the air	very irritant to the upper respiratory tract and lungs (effect may be delayed)
Carbon Monoxide	reduction of carbon dioxide shielding gas and to some extent in all welding operations due to reduction of consumables or incomplete combustion of acetylene	can cause drowsiness, headaches and nausea; unconsciousness and death can result in extreme cases
Carbon Dioxide	shielding gas or combustion product	can be an asphyxiant
Phosgene	formed by the oxidation of chlorinated hydrocarbons (trichloroethylene, etc.) in the atmosphere or on the weld piece	irritation to the respiratory tract (and lung damage) after a latent period of several hours
Phosphine	formed when welding steel coated with rust proofing compound	irritating to the eyes, nose and skin; may also cause serious effects on lungs and other organs
Lack of Oxygen	inert gases (argon, helium, etc.) exclude oxygen from confined spaces (as can carbon dioxide)	can cause asphyxiation
Pyrolysis Products	formed by the thermal decomposition of the resins in primers and paints - could include phenol, formaldehyde, acrolein, isocyanates and hydrogen cyanide	can cause a wide variety of health effects

2.0 Ventilation Requirements

Mechanical ventilation must be provided when:

· there is less than 10,000 cubic feet of space per welder

· ceiling height is less than 16 feet

· welding in a confined space

· fluxes or coatings contain fluorine compound

· base metal or other products involved in the weld include zinc or copper: fumes containing zinc or copper compounds may produce symptoms of nausea, dizziness, or fever, commonly known as metal fume fever.

· Oxygen cutting using a chemical flux or iron powder

· Gas shielded arc cutting

Contaminated air exhausted from a working space must be discharged into the open air and away from sources of fresh intake air.

When work permits, welders should be enclosed in an individual noncombustible booth or screened-in area with an internal, non-reflective surface, with at least 2 feet of circulation at floor level.

ISSUING AUTHORITY	APPENDIX AUTHOR	APPROVAL DATE	EFFECTIVE DATE	EXPIRATION DATE	REV.
ESH&Q Division	Brian Murphy	04/12/05	04/12/05	04/12/08	0

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