Reference

Ototoxic chemicals — certain solvents, metals, asphyxiants and medications — damage hearing on their own and multiply the risk of noise-induced hearing loss, sometimes below exposure limits. Covers the OSHA/NIOSH 2018 bulletin, the chemical classes, affected industries, and how to fold ototoxicants into a hearing program.

Hearing protector fit testing measures what one worker actually gets from one earplug, reported as a personal attenuation rating in decibels. OSHA's February 2026 bulletin calls it a best practice but says a PAR cannot replace the NRR for selection. Covers NRR versus PAR, the 2025 NIOSH change, target PAR, and a worked example.

Wearing earplugs and earmuffs together is the right call above about 100 dBA, but the protection does not add up. This guide explains dual hearing protection: when OSHA and NIOSH call for it, why combined NRR is not the sum of the two devices, how to apply the +5 dB rule, and how to combine plugs and muffs correctly.

A decibel levels chart turns noise numbers into a clear picture of when hearing damage starts and when protection becomes mandatory. This guide charts common tools and environments by dBA, lays out the OSHA 1910.95 permissible exposure limits hour by hour, and shows how to convert a noise level into the right earplug or earmuff NRR.