The ABC's of Welding Fumes.

Welding gases and fumes can be hazardous to your health. The health risks and effects associated with welding gases and fumes are determined by, the length of time that you are exposed to them, the types of welding you do, the protection you use, and the work environment.

All welding processes produce hazardous gases. Gases are invisible to the eye, and may/may not have an odor. The heat in both the flame and the arc, and the ultraviolet radiation from the arc, produce gases such as carbon monoxide, carbon dioxide, oxides of nitrogen and ozone. Other gases and vapors may be produced as by-products from the breakdown of solvents or coatings on the metal. Gases used for arc shielding, or as a fuel, are also given off during welding. Which fumes are produced during welding?

Aluminum
Beryllium
Cadmium Oxides
Chromiun
Copper
Molybdenum
Nickel
Vanadium
Zinc Oxides
Fluorides
Iron Oxide
Lead
Manganese

Welding also produces fumes. Fumes are formed when hot metal vapors cool and condense into very small particles that stay suspended in the vapor or the gas. The particles may be metal or metal compounds, and are often smaller than one micrometer (one fiftieths the width of a human hair). Fumes may be visible or not. Welding “smoke” is an example of a visible fume. But even if the fume can’t be seen, its particles are still present. Which gases are produced during welding?

Carbon Monoxide
Hydrogen Fluoride
Nitrogen Oxide
Ozone

Welding fumes and gases enter our body through the lungs, that is, we inhale them together with the air we breathe. Different gases and fumes affect us in various ways. A healthy body can rid itself of some gases and fumes without lasting effects. Gases such as carbon dioxide and argon, for example, are relatively non-toxic unless inhaled in large quantities. However, gases such as carbon monoxide, nitrogen oxides and ozone are extremely toxic.

The health effects of inhaling fumes depend on the type of fume inhaled. Iron oxides, which are produced during most manual welding processes, are relatively non-toxic. The effects, as currently known, are not permanent unless tobacco smoke or other substances, such as silica and asbestos, have already affected your lungs. Effects such as breathing problems tend to disappear over time - once exposure is reduced or stopped. Exposure to different types of welding fumes produce different health effects. If over the years you breathe in gases, fumes, and vapors in large quantities, your health will suffer.

Some short-term health effects are:

irritation of the eyes, nose, and chest
coughing
shortness of breath
bronchitis
fluid in the lungs (edema)
inflammation of the lungs (pneumonitis)
loss of appetite
cramps
nausea / vomiting

Some long-term health effects are:

chronic lung problems (bronchitis, pneumonia, asthma, emphysema, silicosis, siderosis)
lung cancer
cancer of the larynx
cancer of the urinary tract

Other health problems that may be related to welding fumes are:

skin diseases
hearing loss
gastritis, ulcers of the stomach
kidney damage
heart disease

Smoking puts you at greater risk!

Individual toxic fumes can cause the following health problems:

chromium can cause breathing difficulty, sinus problems, “holes” between the nostrils, and cancer;
manganese can cause Parkinson’s disease, which attacks the nerves and muscles;
cadmium can cause kidney problems and cancer.

The early symptoms of harmful exposure to most substances produced during welding are similar. These may consist of irritation of the eyes, nose, respiratory system and sometimes the skin (such as “nickel itch,” caused by exposure to nickel fumes). Coughing, a tight chest or chest pains, headaches, nausea, vomiting and fatigue may also be some persistent symptoms. Since these symptoms are common to many other illnesses, it is important to determine whether or not they are related to work. If you experience these symptoms, report them to your doctor and explain what you do for a living.

Welding gases and fumes do not normally cause immediate health problems. However, if over the years of working as a welder, you breathe in gases, vapors and fumes in quantities greater than the occupational exposure limits, it is likely that your health will suffer. The seriousness of the hazard depends on the welding process, including the type of metal being welded, and the type of fume generated, but not the total number of fume particles generated. For example, E6010 electrodes used on low-carbon steel generate a large quantity of iron oxide particles. These are relatively non-toxic. However, an E316-15 electrode produces small quantities of highly toxic chromium fumes. The hazard is obviously greater with the E316-15 electrode. The quantity of gases and fumes generated by welding depend on the welding process and other variables such as the type of shielding gas, current, voltage, type of electrode, and the polarity.

If the metal is painted or coated, or has a residual solvent on its surface, welding may generate toxic organic vapors. Research shows that welding polyurethane-coated steels may expose welders up to 25 times the occupational exposure limits for di-isocyanates. It only takes small amounts of chlorinated solvents, such as trichloroethylene or carbon tetrachloride, used for degreasing, to produce dangerous amounts of phosgene gas. Binders and solvents on metal can expose welders to formaldehyde at twice the permitted level. Thus it is essential to allow metals cleaned with chlorinated solvents to dry in a well-ventilated place removed from the welding area. Containers of these fluids must not be stored in the welding area, as welding radiation can react with the vapors.

The amount of ventilation and the welder’s proximity to the work are two other important variables that influence exposure to a welding gas or fume. The amount of available ventilation determines how much of the gases and fumes stay in a welder’s breathing area and for how long. Carbon monoxide levels may reach 500 ppm when the ventilation is not adequate, while the 8-hour OEL for carbon monoxide is 25 ppm. In tests performed under poor ventilation, thermal cutting of steel coated with red lead produced a level of exposure to lead 1000 times the occupational exposure limits. The position and posture of the welder’s body relative to the job also influences the risk to exposure. For example, if you crouch over your work while welding on pipe racks, your breathing area may be directly above the arc.

You can reduce exposure to welding fumes and gases by taking these four steps:

substituting less hazardous flux materials
introducing engineering controls, by using enclosures and improving ventilation
developing administrative controls, such as implementing work-rest schedules and safe-work practices
wearing respiratory protection.

A welder’s work area can be ventilated in several ways. Each method, however, has its limitations. The first one is prevailing winds.In outdoor or semi-outdoor situations, air movement can provide natural ventilation. Its effectiveness, however, depends on whether the day is windy or calm, and whether you are working upwind or downwind. Using welding curtains, spark enclosures or hoardings when working outside prevents exposure to natural air movement and therefore prevents effective ventilation.

The second is general ventilation. In indoor locations and confined spaces, draft fans or air-movers provide general or dilution ventilation. A well-designed and well-maintained ventilation system is usually effective for most situations involving clean, uncoated, mild steels. However, the only means of judging if the system is doing its job is to take regular airflow measurements and to sample for exposure. As a guide, there should be a minimum of 65 cubic meters (2000 cubic feet) of air be moved per minute for each welder in a room. These figures will change if, for example, a plasma-arc machine is being used in the room. Since welding curtains may interfere with airflow, make sure that they are at least 20 centimeters off the floor. Hoardings should have sufficiently large openings to allow good airflow. A rule of thumb often used is that if the visible fume clears within 30 seconds after the welding stops, ventilation is probably adequate.

The third is local exhaust systems.Vent hoods or gun-mounted exhausts can provide local exhaust ventilation. Local exhausts are the most effective ventilation systems for all situations that generate fumes containing heavy metals and, particularly, for stainless steel or plasma-arc welding. In field locations portable hoods may be available. The effectiveness of local exhaust ventilation depends on the distance the hood is from the source of gases and fumes, on the air velocity and on the hood placement. When using local exhaust systems, in general, place vent hoods close to the source of the airborne contaminants, ensure that air moves across the arc at about 0.5 m/s (100 ft./min.)(In processes that use shielding gases, higher air velocities may strip them away.), and place the hood above and to the side of the arc to capture the contaminants. Vent hoods often fail to protect welders because they are poorly designed and located. To properly design and locate the vent hood system you must have a good understanding of the types of contaminants being produced, and of the work procedures and characteristics of the work area. Airflow checks must also be done regularly with a measuring instrument. The checks will ensure that the equipment is working as designed. When using vent hoods, make sure that the exhaust discharges outside the room or confined space.

Know what you can do to help protect yourself. Effective ventilation is the first step to controlling exposure. Check the ventilation system regularly. Before starting work, check that the fan operates properly and the filters are clean. Learn how to use the exhaust system correctly. Secondly, know what materials and hazards you are dealing with. Make sure you read the Material Safety Data Sheet (MSDS) supplied with welding electrodes. It contains information you need to know and understand. You can ask your contractor or supplier for a copy of the MSDS if you do not have one already. Read the MSDS and take the precautions it describes. Thirdly, evaluate the work situation. Are you in a confined space with little or no ventilation? What type of metals are you welding? Are the work pieces clean? Are the work pieces coated, painted or covered with a film of degreasing solvent? When possible, weld on clean metal only. Remove all coatings or paints that are within 5 - 10 centimeters of the weld area. And last, but not least, use respiratory equipment when necessary. The risks of exposure to gases and fumes are high for plasma-arc cutting and for arc gouging and cutting. They are also high when welding stainless and high alloy steel, as well as galvanized, coated and painted steels, even when air-movers and draft fans, or wide-open work areas provide good ventilation. Always use respiratory equipment under such conditions. With poor ventilation and no local exhaust, most jobs, whatever the welding process, will require a respirator.