Welding Fumes and Gases Safety 121

The class Welding Fumes and Gases Safety helps students to understand the dangers of fume and gas generation in welding. The fume plume, a visible cloud of smoke rising from the molten metal, consists of complex metallic oxides and particles formed from the consumable and base metal. Shielding gases used in welding may also produce potentially harmful fumes. Exposure to fumes can be managed through engineering controls, ventilation, proper PPE, and adherence to exposure limits set by OSHA or other organizations. After taking this class, the student will understand the potential dangers of welding fumes and gases, as well as the acute and chronic symptoms that may develop after overexposure. This class discusses how workplace practices and engineering controls can be used to control exposure, in addition to following Permissible Exposure Limits and using air-supplied respirators when necessary.

  • Difficulty Beginner

  • Format Online

  • Number of Lessons 22

  • Language English


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Course Outline
  • Welding Fumes and Gases
  • Welding Fume and Gas Generation
  • Acute and Chronic Exposure
  • Iron Oxides
  • Manganese and Silica
  • Chromium and Nickel
  • Lead, Cadmium, and Zinc in Base Metals
  • Metal Fumes Review
  • Shielding Gas in Welding
  • Dangers of Shielding gases
  • Process Gas
  • UV Rays and Fumes
  • Fume Generation Rate and Welding Processes
  • Gas Fumes Review
  • Fume Control Regulation
  • Engineering Controls and Work Practice Controls
  • Hazard Communication and PPE
  • Controlling Fumes and Reducing Exposure with Natural Ventilation
  • Exhaust Systems
  • Measuring Fume Exposure
  • Handling Fume Overexposure
  • Final Review
  • Describe the dangers posed by the fume plume.
  • Describe the fume plume.
  • Distinguish between acute exposure and chronic exposure.
  • Describe the dangers of iron oxides in welding fumes.
  • Describe the dangers of manganese and silica in welding fumes.
  • Describe the dangers of chromium and nickel fumes.
  • Describe the dangers of common base metals and coatings.
  • Describe the dangers of shielding gases.
  • Describe the dangers of shielding gases.
  • Describe the dangers of process gas generation.
  • Explain the danger of fumes and UV rays.
  • Contrast between different fume generation rates in welding processes.
  • Describe fume control regulation.
  • Explain how engineering controls and work practice controls can be used to control fume exposure.
  • Explain how hazard communication and PPE can lower exposure.
  • Explain how to control fumes with natural ventilation.
  • Explain how to control fumes with exhaust systems.
  • Explain fume exposure measurement.
  • Explain how to handle overexposure to welding fumes and gases.
Vocabulary Term

abrasive blast cleaning

The process of removing surface contaminants by forcibly spraying grit onto a surface. Abrasive blast cleaning can be used to remove base metal coatings before welding.


American Council of Governmental Industrial Hygienists. A member-based organization that recommends and reviews threshold limit values for chemicals used in the workplace. ACGIH guidelines can change if new information about a toxic substance becomes available.


A type of gas that reacts with other elements. Active, inactive, and inert gases are used as shielding gases in some welding processes.


The immediate effects of toxic exposure. Acute exposure symptoms occur during or directly after exposure to fumes.

air-line respirator

Consists of a continuous flow of respirable breathing air with a hose attached to a face piece. An air-line respirator can be used instead of mechanical ventilation.

alloying elements

An element that is intentionally added to a metal in order to change its properties. Alloying elements include nickel and chromium.

ambient sources

Potentially harmful contamination from immediate surroundings in a welding facility. Pollution from ambient sources can include emissions from secondary processes and background welding operations.

arc welding

A welding process that uses the heat generated from electricity to melt filler metal and base metals to form an airtight weld. Arc welding generates intense heat and an electric current.


An inactive gas commonly used as a shielding gas. Argon is much heavier than air and can effectively shield the weld area.


When breathing is obstructed because of inadequate supplies of oxygen. Asphyxiation can lead to death.

Assigned Protection Factor

APF. The workplace level of protection that a respirator is expected to provide 95% of the time. The higher the APR, the more protection provided by the respirator.

base metal

One of the two or more metals to be welded together. The composition of the base metal, and any coatings, adds to the flume plume.

boiling point

The temperature at which a liquid changes to a vapor. When metal is heated above its boiling point, the vapors condense into fine particles.


A soft, bluish-white metal found in zinc ores. Cadmium is commonly used in metal alloys and as a coating on base metals.

carbon dioxide

CO². An active gas commonly used as shielding gas. Carbon dioxide is inexpensive and yields a violent arc.

carbon monoxide

CO. A colorless, odorless, poisonous gas composed of carbon and oxygen. Carbon monoxide may be generated by some welding processes.


Having the potential to cause cancer. Welding fumes are internationally classified as possible carcinogenic risks.

cardiopulmonary resuscitation

CPR. A technique designed to temporarily circulate oxygenated blood through the body of a person whose heart has stopped. CPR can be used when a person has stopped breathing.

ceiling limits

An acceptable exposure limit over a short period of time, usually 15 minutes long. Some substances used in welding may have ceiling limits as the legal exposure limits.

Certified Industrial Hygienist

A person employed to protect and enhance the health and safety of people in the workplace. A Certified Industrial Hygienist is certified by the American Board of Industrial Hygiene.

chlorinated hydrocarbon solvents

Cleaning agents sometimes used on machine-cut parts. If UV rays interact with chlorinated hydrocarbon solvents, phosgene gas can form.


An alloying element commonly used in stainless steel to improve corrosion resistance. Chromium may be converted into hexavalent chromium during welding.


The long-term effects of toxic exposure. Chronic exposure symptoms may occur after a person has spent years working around a specific substance.


Any material that has been applied to the surface of the base metal. Coatings include primer, paint, zinc, and chrome.

complex metallic oxides

A combination of metal oxides and other compounds bound together in an intricate molecular structure that forms in the welding arc. Metal complexes often form the core structure of metal fume particles.


A substance consisting of the atoms of two or more different elements in fixed proportions. Compounds can only be broken down by chemical processes.

confined space

An area with limited means of entry or exit that is large enough for an employee to enter and perform work. Confined spaces in welding include tanks, sewers, and silos.


An electrode that provides filler material for the workpiece when it becomes part of the weld. Consumables generate fumes as they burn into the workpiece.


The deterioration of a material due to chemical reaction with another substance. Some alloying elements or base metal coatings will help to prevent corrosion.

corrosion resistant

The ability of a material to resist chemical destruction from an environment. Chromium and nickel are used as electrode coatings to improve corrosion resistance properties.


A skin condition that causes a red itchy rash. Welders may develop chronic dermatitis due to exposure to hexavalent chromium or nickel.


The device on the welding gun that carries a secondary electric circuit that terminates at the arc. An electrode can be either consumable or non-consumable.


A basic form of a substance that cannot be further subdivided by chemical methods. Elements include substances such as oxygen, hydrogen, and carbon.


A chronic disease of the lungs in which the air sacs of the lung are damaged and enlarged. Low levels of cadmium exposure for an extended period may lead to emphysema.

engineering controls

The primary means of reducing and maintaining employee exposures to at or below the PELs. Engineering controls include substitution, isolation, and ventilation.

exhaust booth

A booth used in welding that provides protection from fumes, spark, heat, and welding splatter. An exhaust booth can be used instead of mechanical ventilation.

exhaust hood

A local fume control device designed to capture and remove harmful welding emissions from the welder’s breathing zone. A local exhaust hood can be used instead of mechanical ventilation.

exhaust systems

Any of various devices used to remove harmful fumes in welding. There are two main types of exhaust used for ventilation in welding: low-vacuum and high-vacuum.


Compounds containing fluorine. Fluoride compounds tend to be corrosive irritants.

flux-cored arc welding

FCAW. An arc welding process that requires a continuously fed consumable electrode. The flux-cored electrode generates a substantial amount of fumes.

fume generation rate

FGR. The rate at which welding fumes are created during a specific, defined welding operation. Each welding process has a different FGR.

fume plume

A cloud-like area above the arc containing welding gases, metallic fumes, and particulates. The fume plume can present an inhalation risk if safety precautions are not followed.


Potentially hazardous gases and particulate matter generated at the electric arc during welding. Welding fumes include particulates from the electrode, flux, shielding gas, base metal, and any coatings included in the weld area.


Metal that has been plated with zinc to improve corrosion resistance. Welding galvanized steel can produce dangerous fumes.

gas metal arc welding

GMAW. An arc welding process in which a bare wire electrode and an inert or active shielding gas are fed to the weld through a welding gun. GMAW can release a combination of shielding gas fumes and fumes generated in the arc that can be dangerous without proper ventilation.

gas tungsten arc welding

GTAW. A precise arc welding process that uses a nonconsumable tungsten electrode. GTAW is also referred to as tungsten inert gas, or TIG, welding.

gas tungsten arc welding

GTAW. A very precise welding process that uses a nonconsumable tungsten electrode. GTAW is also referred to as tungsten inert gas, or TIG, welding.


Gas metal arc welding. An arc welding process in which a bare wire electrode and inert or active shielding gas are fed to the weld through a welding gun. GMAW can release a combination of shielding gas fumes generated in the arc that can be dangerous without proper ventilation.


Gas tungsten arc welding. A very precise arc welding process that uses a nonconsumable tungsten electrode. GTAW is also referred to as tungsten inert gas, or TIG, welding.


A metalworking process in which a harder or tougher material, especially chrome, is applied to base metals. Hardfacing adds a wear-resistant layer to a part and may require more frequent fume measurement.

hazard communication

The means through which employers inform their employees about hazards in the workplace, including training and SDS. Efficient hazard communication can help to limit fume exposure levels.


An inactive gas commonly used as a shielding gas. Helium is much lighter than air and can escape the weld area quickly.

hexavalent chromium

A grayish metal that contains chromium and oxygen. Hexavalent chromium may be added to electrodes to help prevent rust and corrosion in the base metal.

high-alloy steels

A type of steel with high percentages of alloying elements. Stainless steel is a type of high-alloy steel.

high-vacuum low volume

A ventilation system that is meant to exhaust a smaller area. High-vacuum low volume systems are positioned two to six inches (50.8 - 152.4 mm) above the arc and are portable.


A semi-inert shielding gas used in welding. Hydrogen is colorless and odorless.


A type of gas that is inactive and is not chemically reactive. Many welding shielding gases are inert.

International Agency for Research on Cancer

IARC. An intergovernmental agency that conducts and coordinates research on different causes of cancer. The IARC has classified welding fumes as carcinogenic risks.

International Agency for the Research on Cancer

IARC. An intergovernmental agency that conducts and coordinates research on different causes of cancer. The IARC has classified crystalline silica as a carcinogenic risk.

iron oxide

A chemical compound that is a combination of iron and oxygen. Iron oxide forms during a welding operation and can generate harmful fumes.


A soft, heavy, toxic metallic element. Lead produces toxic fumes that can cause health problems after prolonged exposure.

lead oxide

A chemical element containing oxygen and lead. Lead oxide inhalation can lead to lead poisoning.

low-alloy steel

A plain mild steel that contains small amounts of intentionally added materials that change the properties of the metal. Common alloy elements include manganese and nickel.

low-vacuum high volume

A ventilation system commonly used in welding that is designed to remove welding fumes from a large area. Low-vacuum high volume systems are positioned six to fifteen inches (152.4 - 381 mm) above the arc.


A hard, brittle, gray-white metal often added to electrodes. Manganese removes oxides and increases strength and hardness in the weld.

mechanical ventilation

A system for filtering or extracting contaminants from the air. Mechanical ventilation can include exhaust systems and fume extractors.

metal fume fever

An illness caused by exposure to certain welding fumes, typically from galvanized steel or stainless steel welding. The flu-like symptoms normally disappear after one or two days.

National Toxicology Program

NTP. An agency run by the United States Department of Health and Human Services that coordinates, reports on, and evaluates toxicology in public agencies and occupational exposure. The NTP studies the toxicity of welding fumes.

natural ventilation

Supplying and removing air without using a mechanical system. Natural ventilation is provided when welding outdoors.


A corrosion-resistant nonferrous metal. Nickel is commonly added to electrodes and stainless steels to prevent corrosion.


National Institute for Occupational Safety and Health. A federal research agency tasked with researching and developing workplace health and safety recommendations. The NIOSH sets recommended exposure limits for the workplace.


National Institute of Occupational Safety and Health. A federal research agency tasked with researching and developing workplace health and safety recommendations.

nitric oxide

A colorless gas that forms into nitrogen dioxide in the air. Adding nitric oxide to a shielding gas reduces ozone emissions.


A semi-inert gas commonly used as a shielding gas. Nitrogen is commonly used as a shielding gas with stainless steel tube welding.

nitrogen dioxide

A yellow-brown or red-brown gas with an acrid odor. Welding can generate small amounts of nitrogen dioxide, but exposure problems can arise during cutting operations in confined spaces.

nitrogen dioxides

A toxic gas that is created when UV radiation hits the air. Nitrogen dioxide exposure can cause symptoms including headaches, chest pains, and itchiness of the eyes.

occupational exposure limit

OEL. A limit on the allowable concentration of a hazardous substance or class of materials in the workplace. OELs are set by industrial organizations and usually supplement OSHA limits.

Occupational Safety and Health Administration

OSHA. A government agency that sets the standards for working conditions in the United States and ensures that employees work in safe and healthy environments. OSHA welding standards regulate employees’ exposure to chemicals.


A compound containing oxygen and one other element. Complex metallic oxides are created from welding on metal.


A fusion welding process that uses a flame produced by gas containing oxygen and a gas fuel. Oxyfuel welding can create harmful gas fumes.


A colorless, odorless, tasteless gas that naturally exists in the atmosphere. A small amount of oxygen is sometimes used for shielding gas.


A toxic gas that is created when UV radiation hits the air. Ozone can cause symptoms including headaches, chest pains, and itchiness of the eyes.

particulate matter

Solid contaminants including metal, dirt, sand, and dust. The particles formed from welding vapors can be harmful if inhaled.

permissible exposure limit

PEL. The amount of time, based on a time-weighted average for an eight-hour shift, that someone can be exposed to a harmful substance. PELs are set by OSHA.

personal protective equipment

PPE. Articles of clothing or safeguarding devices that employees use to prevent injury in the workplace or on worksites. Wearing the proper PPE can help to limit fume exposure.


A colorless, toxic gas that can form when chlorinated cleaning compounds react with UV radiation produced during arc welding. Phosgene gas overexposure can cause eye irritation and breathing difficulties.

process gas

A gas used in welding to protect the weld puddle and arc from reacting negatively with the atmosphere. Process gases combine with oxygen to form oxides.

pulmonary edema

A respiratory condition resulting in excess fluid that collects in the air sacs of the lungs. Pulmonary edema makes it difficult to breathe.

recommended exposure limits

REL. Fume and chemical occupational exposure limit recommendations set by the National Institute for Occupational Safety and Health. These limits are intended to protect worker safety and health over a working lifetime if used in combination with other safe work practices.


A breathing device worn to prevent inhalation of particles and hazardous substances. Respirators may purify air from the environment or supply air to the wearer.

robot work cell

An automated system used in welding and other industries that includes the robot and the controller. Robot work cells can limit exposure to fumes by isolating the operation.

Safety Data Sheet

SDS. Mandatory information that must accompany almost every chemical in the workplace. An SDS includes sixteen specific sections with details such as the hazards, warnings and precautions, physical and health hazards, and other information associated with overexposure.


A type of gas that can react with other elements. Carbon dioxide is a type of semi-inert shielding gas used in welding.

shielded metal arc welding

SMAW. An arc welding process that uses a flux-coated consumable electrode. Shielded metal arc welding is also referred to as stick welding or manual welding.

shielding gases

A layer of inert gas that protects the weld puddle and arc from atmospheric contamination. Shielding gases are nontoxic, but can be dangerous because they can displace breathable oxygen from the air.


A lung condition in which iron flakes are deposited in lung tissue. Siderosis may be the result of inhaling iron oxides.


A hard compound that is present in a dust form in submerged arc flux welding. Welding flux is also sometimes coated in silica.


A respiratory disease caused by breathing in silica dust. Silicosis can be acute, accelerated, or chronic.

source capture systems

A moveable ventilation device that removes harmful fumes inches away from the arc. Source capture systems are also called source extraction systems.

stainless steel

A high alloy steel with at least 15% chromium or more. Welding on stainless steel can produce hazardous fumes.

submerged arc flux

Granular, fusible material consisting of lime, silica, manganese oxides, and other compounds. Submerged arc flux material protects the welding arc from atmospheric contaminants and also helps to prevent sparks and spatter.

threshold limit value

TLV. A level to which it is believed that a worker can be exposed to a chemical daily and for a prolonged period of time without adverse side effects. TLVs are set by the American Conference of Industrial Hygienists.

time-weighted average

An average exposure over a specified period of time, usually eight hours. OSHA PELs are given as time-weighted averages.


An erosion or lesion that develops on skin or mucus membrane. Stomach ulcers can damage the intestinal tract and are a possible side effect of iron inhalation.

ultraviolet rays

Harmful invisible rays emitted by the arc during arc welding. UV rays can damage vision and burn skin, and can also interact with fumes to form harmful gases.

welding hood

A stationary ventilation device installed above the weld area. The welding hood removes harmful fumes in its surrounding area.

work practice controls

Reducing or maintaining employee exposure by making necessary adjustments in a process and inspecting or repairing engineering control equipment. If work practice and engineering controls cannot lower exposures, employers must provide respirators.

zinc oxide

A combination of zinc and oxygen that is formed during the welding process. Zinc oxide inhalation can lead to metal fume fever.