Airborne hazards in welding
Tips for how to manage them safely
Selecting a respirator for welding is serious business. Choosing the wrong respirator for a job, or using it incorrectly, may cause serious health issues.
Everyone knows that welding can be hazardous, but not everyone realizes just how critical respiratory protection for welders really can be. In fact, the consequences of selecting the wrong respirator for a job, or using it incorrectly, may cause serious health issues. The Occupational Safety and Health Administration’s respiratory protection standard 29 CFR 1910.134 is in place to ensure that workers have the protection they need to protect their health and well-being while working in hazardous environments.
But what are the airborne hazards common in welding, and why are they so worrisome?
Particles, Gases, and Vapors
Studies show that full-time welding may be associated with instances of bronchitis, airway irritation, lung function changes, and other serious health issues. The respiratory hazards welders may encounter primarily fall into one of two categories: particles (including welding fume) and gases and vapors.
Welding fume, the most common airborne contaminant in arc welding, is a complex mixture of very small metal oxide particles. The composition of the base metal, surface coatings, shielding gas or flux, and welding electrode determines which elements are present.
Zinc and hexavalent chromium are both commonly found in welding fume, especially when welding on stainless steel or using stainless steel filler metals.
When burned or exposed to ultraviolet arc rays, electrode coatings, fluxes, shielding gases, and surface coatings can generate gases such as carbon monoxide, ozone, and gaseous fluoride. Operators must be especially careful when welding in enclosed areas or confined spaces, as these locations may have poor ventilation that could lead to very high exposure levels.
Determining Allowable Exposure Levels
As a general rule, the higher the welding amperage used, the more it will generate welding fume and contaminants. Fume generation is also typically much higher when using flux-shielded processes such as shielded metal arc welding (stick) and flux-cored arc welding, as opposed to gas-shielded processes such as gas metal arc welding (GMAW, or MIG) and gas tungsten arc welding (GTAW, or TIG).
However, the amount of fume the welding process generates is only one factor. Other important factors are the position of the welder’s face in relation to the rising smoke plume and the effectiveness of his or her ventilation system.
Since many variables are involved, estimating exposure levels can be difficult. Also, given that each component of the welding fume, gas, or vapor presents unique effects and varying exposure limits, the exposure level to each component must be measured separately. This is why an independent consultant or qualified occupational health specialist such as a certified industrial hygienist, who collects and studies air samples, typically conducts these exposure assessments.
Note that determining exposure levels is a matter of law, as OSHA requires employers to evaluate respiratory hazards in the workplace to determine what hazards are present, what the various exposure levels are, and whether those levels are acceptable.
In addition, employers are required to reassess exposure levels whenever there is a change in the production, process, control equipment, personnel, or work practices that could introduce new hazards or increased exposure levels.
Determining Acceptable Exposure Limits
Occupational exposure limits are typically based on an eight-hour workday. However, for more toxic substances, a ceiling limit may determine the maximum amount of time (for example, 15 minutes) a welding operator may safely be exposed to them.
OSHA’s published permissible exposure limits (PELs) clearly outline the legally enforceable standards, and companies must always ensure that exposures comply with those levels. Companies may also choose to consult other publications, such as threshold limit values (TLVs) published by the American Conference of Governmental Industrial Hygienists (ACGIH), or set other exposure levels—so long as the level selected remains below the PEL.
If an assessment indicates that exposure levels to an airborne contaminant are above OSHA’s allowable limits, a fabricator has two main courses of action to consider: limiting exposure through (1) administrative or (2) engineering means.
The administrative route includes factors such as adjusting an operator’s position, using work breaks, and rotating in relief workers to limit exposure, while the engineering route involves actions such as altering ventilation methods and eliminating hazards.
If there is still no way to effectively reduce the exposure to acceptable levels, respiratory protection must be provided and a formal respiratory protection program must be established.
Creating a Respiratory Protection Plan
Per 29 CFR 1910.134, a written exposure control plan should include a description of the workplace tasks that may expose employees to respiratory hazards; an outline of the engineering controls, work practices, and respiratory protection used to limit exposure to these hazards; and any additional details regarding how the company is taking precautions to limit exposure.
Every respiratory protection program must be reviewed at least once annually, according to 29 CFR 1910.134. To ensure compliance, companies should make sure their program includes documentation and written, worksite-specific procedures for the following:
- Proper respirator selection.
- Fit-testing procedures used when fitting employees with respirators.
- Proper use of respirators in routine as well as potential, foreseeable emergency situations.
- Medical evaluations of employees who are required to use respirators.
- Procedures and schedules for cleaning and disinfecting respirators.
- Procedures for inspecting and repairing respirators.
- Procedures for storing, maintaining, and discarding respirators.
- Precautions taken to ensure adequate quality, quantity, and flow of breathable air for atmosphere-supplying respirators.
- Training given to employees regarding the proper use of respirators, any limitations on their use, and their proper handling and maintenance.
- Training provided to employees regarding the respiratory hazards to which they are potentially exposed during routine work as well as in emergency situations.
- Regular evaluations of the program’s effectiveness.
Selecting a Respirator
Whenever possible, local and area ventilation systems should be used as the first defense against harmful fumes and gases. However, in many cases, engineering and administrative controls are not enough to reduce exposure levels adequately; when this occurs, respiratory protection is required.
Three primary types of respiratory protection equipment are commonly used for welding applications:
- Half-mask respirators. These tight-fitting respirators extend from the nose to the chin and require a tight seal to the face to be effective. Employers should always ensure the half-mask selected fits comfortably underneath a welding helmet without obstructing the operator’s vision.
- Powered-air-purifying respirators (PAPR). A PAPR is an air-purifying respirator that pulls ambient air through an air-purifying element such as a filter or cartridge. It offers a higher level of protection than a half-mask respirator.
- Supplied-air respirators (SAR): Atmosphere-supplying respirators also provide a higher level of protection than a half-mask respirator by providing clean air from an uncontaminated source. However, they reduce mobility because the operator must be attached to an air line. This style of respirator not only allows welders to regulate the airflow, but it also enables them to heat or cool the air entering their helmet.
Any respirator used in a U.S. workplace must be National Institute for Occupational Safety and Health (NIOSH)-approved. OSHA lists the assigned protection factor (APF), which is the level of protection a class of respirator provides when selected and used properly.
When selecting a respirator, first consider the APF needed for the job along with any other protective equipment the operator must wear. For example, if a welder must wear safety glasses, a half-face respirator may compete for space on the bridge of the nose. Next, ensure all options being considered are recommended for welding applications, as not all respirators are flame- and spark-resistant.
The Importance of Fit-Testing
Since faces come in many shapes and sizes, operators may need to try on a variety of models and sizes to find the right fit. Note that welders must watch out for facial hair or anything that breaks the seal between the face and the respirator. This is especially true if they use tight-fitting face pieces (half-mask respirators and certain powered- or supplied-air respirators), as even one-day stubble can cause tight-fitting respirators to leak significantly.
The OSHA standard requires all tight-fitting respirators be fit-tested and that the wearer obtains a satisfactory fit. Fit tests must be repeated for each respirator model considered for use, as well as whenever a physical change occurs that could affect how the respirator fits on the face.
Conducting Medical Evaluations
Certain lung and heart conditions can make wearing a respirator dangerous. For this reason a physician or licensed health care professional must always conduct a medical examination and provide clearance before a welding operator uses a respirator.
In fact, OSHA states that all operators must complete a questionnaire about medical conditions that could affect their ability to safely wear a respirator as well as any workplace conditions or hazards they may encounter.
- All welding operators using a respirator should be re-evaluated by a medical professional whenever:
- They experience symptoms that may affect their ability to safely use a respirator.
- A physician, supervisor, or respiratory program administrator requests an evaluation.
- Information revealed during a fit-testing or program evaluation indicates a need for re-evaluation.
- Changes in workplace conditions increase the burden on the worker, such as higher temperatures, levels of exertion, or equipment needs.
Evaluating a Respiratory Protection Program
Each element of a respiratory protection program should be evaluated regularly, and an assigned respiratory protection administrator should examine all records to ensure tests and inspections are up-to-date.
This program administrator also should observe and talk to those who wear the respiratory protection equipment to ensure the respirators are meeting their needs and being used properly. It is also important to record all evaluations and findings, to note any deficiencies, and to document any necessary corrective measures. Enlisting an outside professional that specializes in safety and compliance, in some cases, may be useful.
Ultimately, implementing and periodically evaluating potential airborne hazards are extraordinarily important. Workers need to breathe, and the air—inhaled directly or through a respirator—should do them no harm.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.