Welding Fumes and Gases Safety 121

abrasive blast cleaning

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

ACGIH

American Conference of Governmental Industrial Hygienists. A member-based organization that works to advance occupational and environmental health. The ACGIH recommends and reviews threshold limit values for chemicals used in the workplace.

active

A type of gas that reacts with other elements. Active gases used as shielding gas for welding include carbon dioxide and oxygen.

acute

Occurring as a result of a single event. Acute exposure symptoms present during or immediately after exposure to fumes.

administrative controls

A modification made to workplace procedures or practices to minimize exposure to hazards. Administrative controls include scheduling breaks, rotating welders, and providing hazard communication training.

air-purifying respirator

APR. A negative-pressure respirator that uses filters, cartridges, or canisters to remove contaminants from ambient air as it passes through them. Air-purifying respirators include simple gas or dust masks as well as powered air-purifying respirators.

alloying elements

A material that is added to a metal in order to change its properties. Alloying elements include nickel and chromium.

aluminum

A silvery-white nonferrous metal that is soft and light and has a high strength-to-weight ratio. Aluminum base metals often contain chromium and nickel.

arc

The area in which electricity moves between the electrode and the workpiece. The heat generated by the arc melts the base metals and filler metal during welding.

arc welding

A group of welding processes that use electricity to generate the heat needed to melt base metals and any filler metal. Arc welding generates intense heat and ultraviolet radiation.

argon

A heavy inert gas commonly used for shielding in arc welding processes. Argon is much heavier than air and can effectively shield the weld area.

asphyxiation

The obstruction of breathing due to an inadequate supply of oxygen. Asphyxiation can lead to death.

assigned protection factor

APF. A number that indicates the level of protection a respirator is expected to provide when used properly. Higher assigned protection factors indicate greater reductions in contaminant concentration within the respirator face-piece and therefore better protection.

asthma

A chronic lung disease characterized by fits of obstructed breathing or coughing. Asthma can be induced or worsened by exposure to welding fumes.

atmosphere-supplying respirator

ASR. A respirator that provides respirable breathing air from a source other than the ambient atmosphere. Atmosphere-supplying respirators include supplied-air respirators and self-contained breathing apparatuses.

atmospheric contaminants

Any element of the surrounding environment that can impact the quality and strength of a finished weld. Atmospheric contaminants are usually ambient gases such as oxygen and nitrogen.

base metals

One of the two or more metals to be welded together to form a joint. The composition of the base metals partially determines the contents of the fume 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 microscopic solid particles.

cadmium

A bluish-white nonferrous metal that is soft and malleable. Cadmium is often used in metal plating because it has excellent corrosion resistance.

cadmium oxide

A chemical compound made of cadmium and oxygen. Cadmium oxide fumes can cause mucous membrane irritation, breathing difficulties, and more severe respiratory issues.

carbon dioxide

CO². A heavy active gas composed of carbon and oxygen that is commonly used for shielding in arc welding processes. Carbon dioxide breaks down into carbon monoxide in the heat of the arc.

carbon monoxide

CO. A colorless, odorless, poisonous gas made of carbon and oxygen. Carbon monoxide is produced when carbon dioxide is heated to high temperatures and dissociates.

carcinogenic

Having the potential to cause cancer. Welding fumes are classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC).

cardiopulmonary resuscitation

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

ceiling limits

The absolute maximum fume concentration to which a person can safely be exposed for any amount of time. Ceiling limits should not be exceeded.

central nervous system

The system that includes the brain, spinal cord, and complex nerve tissues. The central nervous system controls all bodily functions and may be affected by overexposure to some welding fumes.

Certified Industrial Hygienist

CIH. A person trained to anticipate, recognize, evaluate, and develop controls for occupational health and environmental hazards. A Certified Industrial Hygienist is accredited by the American Board of Industrial Hygiene.

chlorinated hydrocarbon solvents

A cleaning agent that contains chlorine. If chlorinated hydrocarbon solvents interact with UV rays, phosgene gas can form.

chromium

A steel-gray nonferrous metal that is hard and shiny. Chromium is often used as an alloying element because it has excellent corrosion resistance.

chronic

Occurring over a period of time. Chronic exposure symptoms present after prolonged, repeated exposure to fumes.

coatings

Any material that is applied to the surface of a base metal to improve its properties. Coatings include paint and plating materials such as zinc and chrome.

complex metallic oxides

A combination of metal oxides and other compounds bound together in an intricate molecular structure. Complex metallic oxides form in the welding arc and constitute a large part of the fume plume.

compounds

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 spaces

An area not designed for continuous human occupancy with limited means of entry or exit that is large enough for an employee to enter and perform work. Welding in confined spaces poses an increased health risk and may require a supplied-air respirator or air quality testing.

consumable electrode

An electrode that conducts electricity to the arc but also melts into the weld as filler metal. Some consumable electrodes also provide shielding that protects the arc and weld puddle.

consumables

Any material that is used up during a welding process. Common welding consumables include electrodes and filler metal, which become part of the weld.

corrosion

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

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Corrosion resistance can be improved by adding alloying elements like chromium and nickel.

current

The flow of electricity through a circuit. Current is measured in amperes (A), or amps, and controls the heat of the arc.

dermatitis

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

elements

A basic form of a substance that cannot be further subdivided by chemical methods. Elements can combine to form compounds.

emphysema

A chronic lung disease that occurs when the air sacs in the lungs are damaged and enlarged. Emphysema is a possible health effect of overexposure to cadmium oxide and nitric oxide.

engineering controls

A modification made to equipment or the workspace to prevent hazards from reaching employees. Engineering controls include installing mechanical ventilation systems and isolating welding processes in robotic workcells.

exhaust booth

A welding enclosure that extracts fumes from the area inside it. Exhaust booths also provide protection from sparks, heat, and spatter.

exhaust hood

A local fume control device designed to capture and remove fumes from the welder's breathing zone. An exhaust hood is positioned over the welding area.

exhaust system

A group of components that draws air out of an area to remove harmful fumes and gases. Exhaust systems for welding are categorized as either low-vacuum, high-volume systems or high-vacuum, low-volume systems.

ferrous metals

A metal that contains iron. Ferrous metals are the most common type of welded materials.

filler metal

Metal deposited into the weld to add strength and mass to the welded joint. Consumable electrodes provide filler metal in some welding processes.

fluoride

A compound containing fluorine, which is a highly toxic gas. Fluoride compounds are typically corrosive irritants.

flux

A nonmetallic material that is intended to protect the weld puddle and solid metal from atmospheric contamination. Flux is often a part of an electrode.

flux-cored arc welding

FCAW. An arc welding process that uses a continuously fed consumable electrode with an inner core of flux. Flux-cored arc welding generates a substantial amount of metal fumes but lower levels of gases.

fume generation rate

FGR. The rate at which welding fumes are created during a specific, defined welding operation. Fume generation rate is measured in milligrams per second or milligrams per minute.

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.

fumes

Airborne particulate matter that behaves similar to a gas. Welding fumes include particulates from the electrode, base metal, and any coatings included on the welding materials.

galvanized

Plated with zinc. Galvanized steel has better corrosion resistance than regular steel.

gas metal arc welding

GMAW. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. Gas metal arc welding releases more gases but less fumes than other arc welding processes.

gas tungsten arc welding

GTAW. A precise arc welding process that uses a nonconsumable tungsten electrode and inert shielding gas. Gas tungsten arc welding releases low levels of metal fumes but high levels of gases.

gases

A fluid phase of matter characterized by the tendency to flow and to expand indefinitely. Gas can be hazardous and undetectable by the five senses.

Globally Harmonized System

GHS. An international standard for communicating chemical hazards through signs, labeling, and Safety Data Sheets. The Globally Harmonized System of Classification and Labeling of Chemicals is intended to make similar hazard communication information available worldwide.

GMAW

Gas metal arc welding. An arc welding process in which a bare wire electrode and shielding gas are fed to the weld through a welding gun. GMAW releases more gases but less fumes than other arc welding processes.

Group 1 agents

A substance classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC). Group 1 agents include welding fumes.

GTAW

Gas tungsten arc welding. A precise arc welding process that uses a non-consumable tungsten electrode and inert shielding gas. GTAW releases low levels of metal fumes but high levels of gases.

hardfacing

A metalworking process that welds a harder or tougher material, especially chrome, to base metals. Hardfacing adds a wear-resistant layer on top of the base metals.

Hazard Communication Standard

HCS. An established OSHA policy that sets guidelines for communicating information about hazardous materials. The Hazard Communication Standard emphasizes the importance of training, labels, and Safety Data Sheets and is aligned with the Globally Harmonized System (GHS) of Classification and Labeling of Chemicals.

helium

A lightweight inert gas sometimes used for shielding in arc welding processes. Helium is much lighter than air and can escape the weld area quickly.

hexavalent chromium

A chemical compound that contains chromium atoms in the +6 oxidation state. Hexavalent chromium fume overexposure can irritate the skin, eyes, nose, and throat, and may lead to cancer in severe cases.

hierarchy of controls

A set of guidelines established by the Occupational Safety and Health Administration that ranks and categorizes workplace safety measures based on level of effectiveness. The hierarchy of controls includes elimination, substitution, engineering controls, administrative controls, and the use of personal protective equipment (PPE).

high-alloy steels

A steel that contains higher amounts of intentionally added materials that change the properties of the metal. Stainless steel is a type of high-alloy steel.

high-vacuum, low-volume systems

An exhaust system designed to remove fumes from a smaller area. High-vacuum, low volume systems are source capture systems that are positioned 2-6 inches (5.08-15.24 cm) above the arc.

hydrogen

A colorless, odorless active gas that is the most abundant element on the planet. Hydrogen is sometimes used for shielding in arc welding processes.

IARC

International Agency for Research on Cancer. An agency dedicated to the promotion of international collaboration in cancer research. The IARC is part of the World Health Organization (WHO).

industrial hygiene

The field concerned with identifying and controlling workplace factors that can cause illness or injury. Members of the industrial hygiene field measure exposure levels and work to establish occupational exposure limits and other guidelines to ensure safety.

inert

A gas that does not react with other elements. Inert gases used as shielding gas for welding include argon and helium.

International Agency for Research on Cancer

IARC. An agency dedicated to the promotion of international collaboration in cancer research. The International Agency for Research on Cancer is part of the World Health Organization (WHO).

iron

A common silver-white metal found in nature as ore. Iron is alloyed with carbon to make steel.

iron oxide

A chemical compound made of iron and oxygen. Iron oxide fume inhalation can cause irritation and respiratory disorders like pulmonary siderosis.

lead

A dull gray nonferrous metal that is soft and heavy. Lead may be present in some painted base metals.

lead oxide

A chemical compound made of lead and oxygen. Lead oxide fume inhalation may cause lead poisoning.

low-alloy steel

A steel that contains small amounts of intentionally added materials that change the properties of the metal. Low-alloy steels include manganese and nickel.

low-vacuum, high-volume systems

An exhaust system designed to remove fumes from a large area. Low-vacuum, high volume systems can be general ventilation systems or source capture systems that are positioned 6-15 inches (15.24-38.10 cm) above the arc.

manganese

A silver-gray nonferrous metal that is hard and brittle. Manganese is often added to steels and electrodes to increase the strength and hardness of a weld.

manganese oxide

A chemical compound made of manganese and oxygen. Manganese oxide fume inhalation can lead to various respiratory and neurological disorders.

mechanical ventilation

A means of supplying fresh air to and removing hazardous fumes and gases from an area that uses a system of devices. Mechanical ventilation is required for many welding processes.

metal fume fever

An acute illness caused by inhaling certain constituents of welding fumes, most commonly zinc oxide. Metal fume fever has flu-like symptoms that normally disappear after one or two days.

micron

A metric measurement equal to 0.001 of a millimeter, or 1/25 of a thousandth of an inch (0.00004 in.). The particles in the fume plume are usually the size of a micron or smaller.

mild steel

A carbon steel that contains less than 0.30% carbon. Mild steels, also known as low-carbon steels, are generally tough, ductile, and easily welded.

mucous membranes

A lining that coats body parts exposed to the outside world and internal organs. Mucous membranes are often irritated by hazardous fumes.

natural ventilation

The movement of air that occurs within an area under normal conditions without the use of specific mechanical devices. Natural ventilation can be used when welding outdoors or indoors if specific regulations are met.

nickel

A silver-white nonferrous metal that is hard but malleable. Nickel is often used as an alloying element to improve corrosion resistance.

nickel oxide

A chemical compound made of nickel and oxygen. Nickel oxide fume exposure can irritate the skin, eyes, nose, and throat, and may lead to cancer in severe cases.

NIOSH

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

nitric oxide

A colorless gas composed of nitrogen and oxygen. Nitric oxide exposure can irritate the eyes, ears, nose, and throat and may cause more severe respiratory diseases.

nitrogen

A colorless, odorless, tasteless active gas that naturally makes up 78% of breathable air. Nitrogen is commonly used for shielding in arc welding processes.

nitrogen dioxide

A toxic yellow-brown or red-brown gas composed of nitrogen and oxygen that has an acrid odor. Nitrogen dioxide can result from UV radiation interacting with atmospheric nitrogen or nitric oxide interacting with atmospheric oxygen.

nitrogen oxides

Any gas composed of nitrogen and oxygen. Nitrogen oxides include nitric oxide and nitrogen dioxide.

occupational exposure limits

OELs. The maximum acceptable concentration of hazardous fumes to which a person can be exposed in the workplace without the potential for adverse health effects. Individual companies may set their own occupational exposure limits based on those established by regulatory organizations or their own internal guidelines.

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. The Occupational Safety and Health Administration sets the only legally enforceable occupational exposure limits (OELs) in the United States, which are known as permissible exposure limits (PELs).

OSHA

Occupational Safety and Health Administration. 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 sets the only legally enforceable occupational exposure limits (OELs) in the United States, which are known as permissible exposure limits (PELs).

oxidation

A material's chemical reaction with oxygen. Oxidation takes place in the welding arc when the heated metal reacts with oxygen in the atmosphere.

oxides

A chemical compound containing oxygen and one other element. Oxides form when metals and gases are heated during welding.

oxygen

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

ozone

A toxic gas that forms when UV radiation interacts with oxygen in the air. Ozone exposure can cause headaches, chest pains, and itchiness of the eyes.

particulate matter

A solid contaminant that consists of microscopic particles of metal, dirt, sand, or dust. The metal vapors created by welding condense into particulate matter that can be harmful if inhaled.

parts per million

ppm. A measurement of the ratio of one substance to another. One part per million means a ratio of one to one million.

PELs

Permissible exposure limits. An occupational exposure limit set by the Occupational Safety and Health Administration that is legally enforced. PELs are usually given as a time-weighted average over eight hours.

permissible exposure limits

PELs. An occupational exposure limit set by the Occupational Safety and Health Administration that is legally enforced. Permissible exposure limits are usually given as a time-weighted average over eight hours.

personal protective equipment

PPE. Any clothing or device used to minimize exposure to hazards and prevent injury. Personal protective equipment such as respirators can help limit fume exposure.

phosgene

A colorless toxic gas released when chlorinated cleaning solvents react with UV radiation during arc welding. Phosgene exposure can cause eye irritation, breathing difficulties, and low blood pressure.

plating

The process of adding a thin layer of metal to serve as a decorative or protective coating on a part. Plating is used to improve the appearance or functionality of parts.

powered air-purifying respirator

PAPR. An air-purifying respirator that uses a motorized fan to force ambient air through filtering devices. Powered air-purifying respirators are commonly used in welding.

PPE

Personal protective equipment. Any clothing or device used to minimize exposure to hazards and prevent injury. PPE such as respirators can help limit fume exposure.

pulmonary diseases

An illness that affects the lungs and respiratory system. Pulmonary diseases include emphysema and edema.

pulmonary edema

A chronic respiratory condition that occurs when excess fluid collects in the air sacs in the lungs. Pulmonary edema is a possible health effect of nitric oxide and cadmium oxide exposure.

pulmonary siderosis

A lung condition that occurs when flakes of iron are deposited in lung tissue. Pulmonary siderosis may result from prolonged inhalation of iron oxides.

recommended exposure limits

RELs. An occupational exposure limit set by the National Institute for Occupational Safety and Health. Recommended exposure limits are not legally enforced, but they are often used to supplement the legal limits set by OSHA.

red blood cell

A component of the body that transports oxygen from the lungs to other tissues. A low red blood cell count can cause symptoms like tiredness and weakness.

respirator

A breathing device worn to prevent the inhalation of hazardous substances. Respirators may filter particles, dust, fumes, and gases from air in the environment or supply clean air from a different source.

respiratory system

The system composed of the organs involved in the breathing of air. The respiratory system includes the nose, trachea, and lungs.

robotic workcell

An enclosed area that contains a robot and any external devices or equipment that interact with the robot to perform work, such as welding. Robotic workcells can be used as an engineering control to isolate hazardous fumes.

Safety Data Sheets

SDSs. A mandatory document containing important information that must accompany almost every chemical in the workplace. A Safety Data Sheet consists of several sections that detail information such as the components of a chemical and the hazards, precautions, and first aid procedures associated with the chemical.

SAR

Supplied-air respirator. An atmosphere-supplying respirator that consists of a face mask with a hose that connects to a compressed air system. An SAR provides a continuous flow of breathable air.

scientific consensus values

A quantity or measurement attributed to a specific variable by the majority of scientists in the corresponding field. Scientific consensus values for industrial hygiene are used to establish occupational exposure limits.

shielded metal arc welding

SMAW. An arc welding process that uses a flux-coated rod as a consumable electrode. Shielded metal arc welding can produce high levels of metal fumes but generates less gases than other arc welding processes.

shielding gas

A gas that protects the weld puddle and arc from atmospheric contamination. Shielding gases are nontoxic but can displace breathable oxygen from the air and some can form other hazardous gases in the arc.

short-term exposure limits

STELs. The maximum fume concentration to which a person can safely be exposed for short periods of time. Short-term exposure limits are usually given as a time-weighted average over 15 minutes.

source capture systems

A portable exhaust device that is positioned inches away from the arc to remove harmful fumes. Source capture systems, also known as source extraction systems, can be either high-vacuum, low-volume systems or low-vacuum, high-volume systems.

source extraction systems

A portable exhaust device that is positioned inches away from the arc to remove harmful fumes. Source extraction systems, also known as source capture systems, can be either high-vacuum, low-volume systems or low-vacuum, high-volume systems.

stainless steel

A high alloy steel that contains at least 10.5% chromium and exhibits excellent hardness and corrosion resistance. Measuring fume exposure levels is especially important when welding stainless steel.

steel

An alloy of iron and carbon containing less than 2.0% carbon. Steels often contain other elements to enhance various aspects of the metal.

supplied-air respirator

SAR. An atmosphere-supplying respirator that consists of a face mask with a hose that connects to a compressed air system. A supplied-air respirator provides a continuous flow of breathable air.

threshold limit values

TLVs. An occupational exposure limit set by the American Conference of Governmental Industrial Hygienists. Threshold limit values are not legally enforced, but they are often used to supplement the legal limits set by OSHA.

time-weighted average

TWA. The average concentration of fumes to which a person is exposed over the course of a specified period of time. Time-weighted averages for occupational exposure limits, such as PELs, are typically given for eight-hour time periods.

TLVs

Threshold limit values. An occupational exposure limit set by the American Conference of Industrial Hygienists. TLVs are not legally enforced, but they are often used to supplement the legal limits set by OSHA.

ulcers

An erosion or lesion that develops on skin or mucous membranes, such as the stomach. Stomach ulcers can damage the intestinal tract and are a possible side effect of iron inhalation.

ultraviolet

UV. Harmful invisible light rays emitted by the arc during arc welding. Ultraviolet radiation can damage vision, burn skin, and form hazardous gases if it interacts with certain elements or compounds.

vaporize

To change from a liquid to a gas. Metals vaporize when heated above their boiling point.

velocity

An object or substance's speed in a given direction of motion. Low-vacuum, high-volume systems move air at low velocities and high-vacuum, low-volume systems move air at high velocities.

ventilation

A means of moving air to remove contaminants and provide clean air. Ventilation reduces the hazards posed by welding fumes and gases.

weld puddle

The small area of molten metal that forms during welding. The cooled weld puddle forms the permanent joint.

welding helmet

A heat-resistant head covering that consists of a hard face-guard and a dark-tinted filter plate. Welding helmets protect welders from flying debris and the intense ultraviolet light produced by the arc and may reduce exposure to welding fumes.

zinc

A bluish-white nonferrous metal that is corrosion-resistant and has a relatively low melting point. Zinc is used to plate galvanized steel.

zinc oxide

A chemical compound made of zinc and oxygen. Zinc oxide fume inhalation is a common cause of metal fume fever.