4.2 Personal Attenuation Rating (PAR)
Fit Testing Evidence
PAR measures real-world protection for the individual, not a laboratory average
Directly subtracted from workplace noise level (dBA) to calculate protected exposure
Reveals whether hearing protection actually reduces exposure below the 87 dB(A) Exposure Limit Value
Identifies workers whose protection is inadequate despite using "correctly rated" equipment
Enables selection of the right protector for each individual's ear canal and fitting technique
What PAR tells you:
A Personal Attenuation Rating (PAR) is a single number, in decibels, showing how much noise reduction a specific person achieves when wearing their hearing protection. It answers the question: "Is this worker actually protected?"
Why it matters:
Manufacturer ratings like SNR (Single Number Rating) are laboratory averages tested on small groups under ideal conditions. Research shows real-world attenuation is often significantly lower — HSE RR720 found many workers achieve less than half the rated protection.
PAR eliminates this guesswork. It measures what that individual, with their ear canal shape, fitting technique, and specific protector, actually achieves.
How it's used:
To check adequacy, subtract the PAR from the workplace noise level:
Protected exposure = Workplace dBA − PAR
If the result exceeds 87 dB(A), the hearing protection is inadequate for that worker and alternatives must be considered.
Regulatory context:
Regulation 7(4) of CNaWR 2005 requires employers to select hearing protection that is adequate and suitable. PAR measurement provides documented evidence of adequacy for individual workers — essential for demonstrating compliance if challenged. Ref: https://multimedia.3m.com/mws/media/927828O/personal-attenuation-rating.pdf https://www.bohs.org/app/uploads/2022/02/UKHCA-Hearing-Protection-Fit-Testing-An-Introductory-Guide.pdf