Work out noise exposure dose instantly with clear inputs, formula shown and shareable results.
Permitted exposure halves for each exchange-rate increment above the criterion level. Under NIOSH's 3 dB rule and 85 dBA criterion, 92 dBA allows only 1.59 hours, so four hours is a 252% dose - well over the limit. OSHA's 5 dB rule is more permissive, allowing 3.5 hours at the same level, which is why the two standards disagree so often.
Permitted time
T = 8 / 2^((L - criterion) / exchange rate)
Dose
dose = actual hours / permitted hours x 100%
NIOSH's 3 dB exchange reflects equal energy, which is physically correct. OSHA's 5 dB rule is a historical regulatory compromise.
The maximum daily exposure considered acceptable. Above it, cumulative hearing damage risk rises measurably over a working lifetime.