r99

Questions

What does r99 mean?

R99; Ellipsis of NIOSH R99.

Where does r99 come from?

From Initialism of Resistant to oil particles with 99% filtration efficiency in NIOSH air filtration ratings.

How to pronounce r99

1. Open the pronunciation page — Open the Speakur entry for “r99”.
2. Read the phonetic spelling — Read the IPA spelling () so you know which sounds to aim for.
3. Play the audio — Click Play to hear reference audio for “r99”.
4. Repeat and practice — Say “r99” aloud, matching stress and vowels until it feels natural.