In our latest installment of Ask the Expert, brought to you by the team of industry experts at EHS Hero®, we look at a recent question from a subscriber asking whether an N95 or N99 mask protects the user from fumes when cutting stainless steel. See what the experts had to say.
Q: Does an N95 or N99 mask protect the user from fumes created by cutting stainless steel?
The respirator you choose to use in your workplace must reduce employee exposure to or below the PELs for the constituent parts of the metal fume. These PELs can be found in 29 CFR 1910.1000, Table Z-1. Stainless steel welding and cutting fume releases chromium and nickel in addition to other components. However, because each component of welding fume has unique effects and exposure limits, the exposure level of each component must be measured separately. Exposure tests typically involve the collection of air samples by a qualified safety specialist, such as a Certified Industrial Hygienist.
Though N95 filters are recommended for most cutting and welding applications because welding fume is relatively easy to filter and oil mist is seldom a factor, because cutting stainless steel involves high hazard compounds such as chromium, P100 filters must be used.
Specifically, OSHA requires employers ensure no employee is exposed to an airborne concentration of chromium in excess of 5 micrograms per cubic meter of air (5 µg/m3), calculated as an 8-hour time-weighted average. Consequently, a powered air purifying respirator with a particle filter is typically recommended.
Additionally, plasma cutting in particular creates high temperatures, which can emit damaging oxides of nitrogen, such as nitrogen dioxide and nitric oxide. These are hazardous to inhale in high concentrations, such as when welding in confined, poorly ventilated areas. Consequently, we recommend that a supplied air respirator be used in such cases.
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