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New Guidelines Signal Lower Threshold Limits for Manganese

October 24, 2016

Recent changes to manganese exposure limits will have an effect on numerous industries and industrial processes.  Manganese, a grey-white metal resembling iron, is used to produce a number of important alloys as well as to desulfurize and deoxidize steel.  Found in many welding rods and filler metals, manganese is combustible, and finely dispersed particles can form explosive mixtures in air (NIOSH/IPCS 2003).  Manganese oxide fumes are produced when the metal is heated and reacts with oxygen in the air.

Recent studies indicate neurological and neurobehavioral deficits may occur when workers are exposed to low levels of manganese (<0.2 mg/m3) in welding fumes. These effects include changes in mood and short-term memory, altered reaction time, and reduced hand-eye coordination. Chronic exposure to manganese oxide fumes can lead to damage to the central nervous system. Welders are especially susceptible to this disease, called maganism. Manganese oxide has gained so much attention as a hazardous element found in welding fumes that it has warranted a closer study of its side effects. The American Conference of Governmental Industrial Hygienists (ACGIH) has revised previous opinion of what the safe level of manganese ingestion is considered to be and has made new recommendations to the levels that welders should be exposed to.  Many industries set the allowable exposure limit at 0.2 milligrams per cubic meter, or mg/m3, over and eight-hour work day.  The new ACGIH report sets that allowable exposure at only 0.02 mg/m3 for worker health to be maintained.

The ACGIH also issued new guidance for inhalable manganese, particulate that can be inhaled into the nose and mouth but not likely to be inhaled into the deep lungs because of size. These larger particles might result from grinding activities rather than welding. The new recommended TLV-TWA for inhalable manganese is 0.1 mg/m3.  Since many metal fabricators use these guidelines to manage employee exposure, many facilities are forced to make changes to their traditionally-provided personal protective equipment.

With the drastic decrease in allowable exposure over the workday, most current factory ventilation systems are no longer adequate. Manganese adds strength and hardness to manufactured products. It also makes steel impervious to the depredations of corrosion. Due to these factors, it is almost irreplaceable as a part of industrial manufacturing, and a need exists for products that limit welder exposure to manganese.

Clean Air America provides custom-engineered and innovative products that can assist in welding fume ventilation to help your plant stay within OSHA and ACGIH guidelines. Clean Air America’s experienced team of engineers can also develop a custom solution for your plant to ensure productivity and health of your welders is constantly protected.

Uncategorized, Welding Smoke Filtration

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