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From Initialism of Not resistant to oil particles with 100% filtration efficiency in NIOSH air filtration ratings.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: N100 standard Full definition →
From Initialism of Not resistant to oil particles with 100% filtration efficiency in NIOSH air filtration ratings.
Etymology from Wiktionary, CC BY-SA 4.0.