The Updated Recommended Manganese Exposure Levels—And Why They’re So Important

When it comes to potential exposure of employees to toxic substances, and the liabilities associated with it, it’s important to stay on top of the latest guidelines. Currently, concern is being placed on Manganese, as its risk potential is very high, with exposure leading to central nervous system damage. While OSHA has addressed the hazards of Manganese with a permissible exposure level (PEL), this has not been changed since 1969. In fact, their established levels are well above what is actually safe.

As a result of the need for updated, safer guidelines, the American Conference of Governmental Industrial Hygienists (ACGIH) has established more relevant recommended exposure limits, which are being widely recognized by the industry. OSHA’s PEL is 5.0 milligrams per cubic meter, while ACGIH’s recommended exposure limit (TLV) was 0.2, and as of January 2013, is 0.1 mg per cubic meter for inhalable particles and 0.02 for respirable particles (dealing with the lower respiratory system, where there is significant absorption of Mn). As a result, the recommended exposure level has decreased by 50-90%.

Pertaining mainly to welders, whose exposure to manganese is great—Mn is added to welding electrodes and wire—these new guidelines provide a much safer limit to this toxic metal. Air sampling is the recommended way to evaluate exposure to respirable Mn. The type of air sampling has now changed, with the filter now being placed in a small cyclone that separates particles. Upon sampling, if measured total Manganese exposures are 0.02 or greater, chances are you are exceeding the new TLV. In that case, be sure to evaluate your use of respiratory protection and consider improving exhaust ventilation.

While the new levels and sampling measures could be challenging to welding operations, they are a crucial way to ensure worker safety—and are long overdue.

You can compare OSHA’s and ACGIH’s levels here and visit the ACGIH website for more information.