How to Read the NRR (Noise Reduction Rating): The EPA Label, OSHA Derating, and Dual Protection Math | WC Safety
The NRR on every earplug and earmuff is a laboratory number, not the protection you actually get on the floor of a plant. This guide shows you how to read the NRR on the EPA label, apply the OSHA 50 percent derating rule and the NIOSH (NRR-7)/2 formula, and calculate combined attenuation when you double up earplugs and earmuffs together.
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