Escape the 'Silent Killer'

How proper protection can help prevent respiratory disease

Practical Welding Today March/April 2003
March 27, 2003
By: David S. Luther

It was just a 20-minute welding job in a basement boiler-room, but it left the plumber feeling lightheaded and nauseated and gave him a headache that lasted until the next morning.

Like this plumber, many professionals who occasionally weld, braze, or cut metals don't wear respirators because they think infrequent exposure to fumes and gases produced by the process won't cause lasting damage.

However, numerous health hazards are associated with even short exposure to fumes, gases, and vapors released during welding, cutting, and brazing. These hazards vary, depending on the type of welding materials and welding surfaces.

Although the plumber got a headache, welders might not experience any immediate physical effects from limited exposures to welding fumes and gases. While certain environments can cause immediate illness and even death, serious health damage typically comes from effects that slowly accumulate over many years. This is why the causes of respiratory disease often are called "silent killers."

So how do you avoid the silent killer? Basic steps are identification, evaluation, and control.


Contaminants in your environment will depend on the composition of the materials you use; their coatings; and the fluxes, filler materials, and cleaning and degreasing compounds you use.

Fumes are particulates and are distinct from gases in that they contain metals and other substances that are generated in the welding process and then condensed into microscopic particles that you can breathe in easily.

You also might use or produce gases that either are toxic or can displace oxygen in poorly ventilated areas, causing dizziness, unconsciousness, and death. Gases commonly found in welding, brazing and cutting environments are carbon monoxide, carbon dioxide, nitrogen oxide, nitrogen dioxide, and ozone. Depending on the materials you weld, their coatings, and solvents or fluxes used, other harmful gases, such as fluorine, can result.

Material Safety Data Sheets (MSDSs) serve as the primary reference for determining the hazards associated with a particular substance. You can get these sheets from the company that supplies or manufactures the material in use. MSDSs define a substance's characteristics; fire, explosion, and health hazards; precautions for safe handling and use; and ways to control its dangers.

Air sampling or monitoring is necessary to give you a more precise picture of the hazardous gases or fumes that your particular welding or brazing process produces in your workspace.

When requiring such services, contact your company's workers' compensation insurance carrier to see if it can help; it might be able to do this type of testing as part of its coverage program. Other resources for these services include your state health department, commercial industrial hygiene service providers, and the Occupational Health and Safety Administration (OSHA).


To help you evaluate your exposure level to workplace contaminants and select a respirator, you will need to compare the results of your air sampling tests with the permissible exposure limit (PEL) published by OSHA and the threshold limit value (TLV®) of the American Conference of Governmental Industrial Hygienists (ACGIH®) for each contaminant.

TLVs are not standards; they are guidelines designed for use by industrial hygienists in making decisions regarding safe levels of exposure to chemical substances and physical agents found in the workplace. The ACGIH publishes its TLVs annually.

When using a TLV, industrial hygienists are cautioned that it's only one of many factors to consider in evaluating specific workplace conditions. An occupational health consultant or respirator manufacturer can help you determine which respirator to use by consulting a respirator selection guide.

Figure 1

Figure 1 shows excerpts from a respirator selection guide. It includes a sampling of substances found in welding, brazing, and cutting operations and the recommended respirator for various concentrations of the substance. The second column shows the Chemical Abstracts Service (CAS) registry number, a universal reference number that can be used to search for more information. The next two columns list the PEL and TLV—the permissible exposure levels that OSHA and the ACGIH recommend for each substance.

The immediately dangerous to life or health, or IDLH, value column lists a concentration value at or above which a self-contained breathing apparatus (SCBA) or pressure-demand air-line respirator with an emergency escape cylinder must be used. Below that value, you can use an air-purifying respirator with cartridges and/or filters or a continuous-flow supplied-air respirator.

The next column provides a hierarchy of maximum use concentrations. You must compare the concentrations of the same substance or contaminant found in your work area against these concentrations.


How you control the fumes, vapors, and gases from welding, brazing, and cutting depends first on engineering solutions, such as proper ventilation, and reducing the danger through safe work practices, administrative controls, and substitution of less hazardous materials and processes.

Ventilation requirements are specified in OSHA's 29CFR1910.252 regulation, which covers welding, cutting, and brazing.

Respiratory protection is the last line of defense against the silent killer. Respiratory recommendations based on workplace exposure concentrations are shows in Figure 1.

Filtering facepiece. This respirator type protects against particulates but not against toxic gases or vapors. Filtering facepieces rated at N-95 provide a minimum efficiency of 95 percent for particulates free of oil.

Replaceable filter. These filters are available in three classes: N, R, and P, and three efficiencies: 95, 99, and 100. Any R or P filters can be used for any particulates, including those in oily environments.

Reusable half-mask particulate respirator with replaceable filter. The reusable half-mask has an inhalation valve to keep the filter dry and allows you to perform a positive-pressure seal check. A stainless steel mesh cover on some welding versions protects you from heat, sparks, and slag.

Half-mask respirator combined with cartridge and filter. This respirator type is designed to protect against specific gases, vapors, and particulates when their concentration levels exceed the PEL or TLV, but is below the concentration level that requires a full-facepiece air-purifying respirator.

Full-facepiece respirator combined with cartridge and filter. This respirator provides eye, face, and respiratory protection in non-IDLH environments. Many full-facepiece welding respirators are designed with a flip-up welding lens; some also have a flip-up welder's shield that covers the respirator's complete lens and releases to provide even wider range of vision.

Backpack adapter. This accessory is particularly suited to welding. It enables filters and cartridges in air-purifying respirators to be placed outside the heated plume of welding gases, vapors, and particulates. Extension tubes enable you to place the filter elements in a pack on your back instead of on your facepiece.

Supplied-air respirator (SAR). These are available with either a half or full facepiece that connects to a source of breathable air with an air supply hose.

Self-contained breathing apparatus (SCBA) or a pressure-demand air-line respirator (PDAR) with emergency escape cylinder is required in IDLH areas.

Beyond Respirator Selection

These are a few of the practical considerations in selecting respiratory protection for use in welding, brazing, or metal cutting operations. In addition to selecting an appropriate respirator, you should participate in a written respirator program and follow appropriate guidelines for testing for fit; changing cartridges; and properly cleaning, sanitizing, maintaining, and storing respirator equipment.

Pertinent details describing the elements of a respirator program are specified in OSHA's 29CFR1910.134 respiratory protection regulation.

All of these issues, as well as prerequisite engineering solutions such as size of welding booths and ventilation systems are addressed in the "Small Entity Compliance Guide for the Revised Respiratory Protection Standard 29CFR1910. 134." The guide can be found on OSHA's Web site.

Without taking proper precautions in an environment that requires respiratory protection, you—like the plumber—at first may be only a few minutes away from being quickly overcome by or becoming one of many who face debilitating respiratory diseases in later life. Treat all welding fumes, vapors, and gases as potentially harmful, and use all available protection.

David S. Luther is product support manager of North Safety Products, 2000 Plainfield Pike, Cranston, RI 02921, 800-430-4110, fax 800-572-6346, North Safety Products is an occupational health and safety products manufacturer that offers personal protective equipment, including head, hearing, eye, face, respiratory, hand, and fall protection; lockout-tagout equipment; protective footwear; first-aid, and controlled environment safety products.

American Conference of Governmental Industrial Hygienists, 1330 Kemper Meadow Drive, Cincinnati, OH 45240, 513-742-2020,

Occupational Safety and Health Administration, 200 Constitution Ave. N.W., Washington, DC 20210, 800-321-6742,

David S. Luther

Contributing Writer

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