Effectively controlling hazardous welding fumes and gases

Every day thousands of welders worldwide are exposed to dangerous welding fumes and gases that make them sick, sometimes permanently. At the same time, the Occupational Safety and Health Administration (OSHA) specifies comprehensive regulations and standards designed to help ensure safety when welding and avoid welding fumes polluting the work environment.

The problem is that hazardous fumes and gases are invisible, which makes it impossible to visually gauge the effectiveness of ventilation. Further, the reality is that many companies underestimate the impact of fume exposure and don't use effective means to extract, filter, or purify the air welders work in.

Health Risks of Hazardous Fumes

The U.S. Department of Labor warns that breathing welding fumes can cause both short-term and long-term negative health effects, including:

• Eye, throat, and nose irritations; nausea; and dizziness.
• Metal fume fever, with flu-type symptoms that include coughing, muscle and joint pain, fever, and chills.
• Kidney damage, stomach ulcers, and damage to the central nervous system.
• Respiratory disease and lung damage, including pneumoconiosis (black lung).
• Cancer.
• Parkinsonian syndrome.
• Suffocation, and even asphyxiation, when gases like helium, argon, and carbon dioxide displace the oxygen in the air in enclosed or confined spaces.

The type and degree of potential damage depends on what is being welded and which welding process is used. It also depends on where welders are working and. ultimately, the amount of air movement and what ventilation controls are in place.

Those welding in confined spaces are at greatest risk.

While OSHA provides the minimum safety standards for the industry, many companies misinterpret these, seriously underestimating the need for air filtration and effective ventilation.  

OSHA Guidelines to Reduce and Minimize Exposure to Welding Fumes

OSHA gives good basic guidelines that help to reduce exposure to welding fumes. However, it does not specify what equipment should be used within the workplace. Instead it is up to those in the industry to identify and use the proper equipment available to keep employees safe.

OSHA warns that simply working outdoors does not guarantee adequate ventilation, and proper positioning is essential if ventilation and exhaust systems are not used.

It also advises that local exhaust ventilation systems can successfully remove fumes and gases from welders' breathing zones. For instance, a portable vacuum extraction exhaust system can be positioned to draw fumes and gases away from the welder.

Additionally, OHSA's permissible exposure limit (PEL) for an eight-hour working day is 5 mg/m3, which is the equivalent of five cubes of sugar dissolved in a 164-ft. by 65.6-ft. swimming pool full of water 3.28-ft. deep. Anyone who is exposed to more fumes than this is at risk.

The shocking reality is that most welders are exposed to 25 to 1,000 times this limit daily.

Unfortunately, the truth is that companies often think they are complying with OSHA's minimum specifications, and therefore keeping their employees safe, but often they are not. For instance, a common misconception is that simply keeping windows open and using fans to circulate air stop harmful fumes from affecting welders. Nothing could be further from the truth.

Equipment to Control Hazardous Welding Fumes

OSHA's regulations for mechanical ventilation require that welding fumes and smoke must be kept within safe limits. General mechanical ventilation must be able to produce as many air changes as possible to do this. Local exhaust ventilation must consist of freely movable hoods that can be placed as close as possible to the metal being welded. Contaminated air must be discharged into open air, or somewhere that is clear for the source of clean intake air.

Opening windows to allow fumes to escape does not meet OSHA specifications. Furthermore, when welders work in confined spaces, where ventilation is poor, where several welders work together indoors, or when welders work outside on windless days, they are at increased risk to illegal exposure limits.

The solution is to use smoke filters to remove the fumes and toxic gases. But these need to work efficiently and not get in the way of welders; if they are in the way, welders won't use them despite the health risks.

The most effective way to remove hazardous smoke, gases, and fumes is at the source (which is the work being welded) via an extraction system. The next best solution is ventilation equipment, although in many instances it is advisable to use both together.

Removing Fumes at the Source

An example of an effective exhaust unit design is one that has a pivoting hood that rotates in all positions and catches fumes and gases in front, at the side, or underneath the work being welded. It should also have a good suction action.

A wall-mounted mechanical unit needs to be able to swivel 360 degrees and have lightweight, flexible arms that reach the welder, but do not get in his way.

Cartridge filter units should extract smoke and be self-cleaning. Rotating nozzles are preferable.

Good-quality portable devices work on vacuum extraction. High-quality filters, capable of 99.9 percent efficiency, typically require minimal maintenance.

Effective Ventilation

Where local extraction is insufficient or impractical, a good ventilation system removes fine dust and fumes.

Traditionally, push/pull systems are used, particularly in large welding halls and on large, complicated components. A circular airflow is maintained as warm, contaminated air rises and is pulled into the pipe system, while what is assumed to be clean air is pushed out into the production hall. Push/pull systems incorporate pipes with ventilation grilles that, unfortunately, can mix the clean air with welding fumes and dust.

Another option is a system that uses layer ventilation and displacement flow principles with cleanable filters. Instead of an extensive pipe system, this relies on a central air tower without ductwork or hoses. These are particularly useful where local exhaust ventilation isn't possible, and where the source of fumes and welding dust changes.

As the warm contaminated air and fine welding dust rise, they are pulled into the top of an automatic filter system. Purified air then is returned via low-level outlets, directly into the welders' breathing zone. Air turbulence is minimal, so dust and fumes don't get mixed with the clean air.

At the end of the day, there is no doubt that welders are healthier, happier, and more productive if they are using  good-quality extraction, filter, and ventilation systems that effectively remove smoke, dust, and welding fumes. Better still, employers and welders are better able to rest assured that they won't become sick or permanently disabled.