Calculate safe exposure time and daily noise dose.
NIOSH recommends max 85 dB for 8 hours. For every 3 dB increase, safe exposure time halves: 88 dB = 4 hours, 91 dB = 2 hours, 100 dB = 15 minutes. Noise dose = (actual time / safe time) × 100%. Dose > 100% exceeds limits. Common sources: conversation 60 dB, vacuum 70 dB, concert 110 dB.