Noise Exposure Calculator (OSHA or NIOSH Dose)

This noise exposure calculator totals one, two, or three occupational noise exposures under one selected criterion. OSHA and NIOSH use different criterion levels and exchange rates, so their dose percentages must not be mixed or treated as interchangeable.

Entries and criteria

Choose OSHA or NIOSH, select the number of exposures, and enter each level in dB and duration in hours. The starting case is one 85 dB exposure lasting 8 hours. Levels are accepted from 70 to 140 dB and durations from 0.1 to 24 hours.

The allowed time $T$ at level $L$ is:

$T_{\text{OSHA}}=8\times2^{-(L-90)/5}$

$T_{\text{NIOSH}}=8\times2^{-(L-85)/3}$

Each exposure contributes:

$\text{dose contribution}=100\times\frac{\text{duration}}{T}$

Contributions are added for the selected exposures. The result also reports criterion time at the highest entered level.

Worked criterion comparison

Under OSHA, the allowed time at 85 dB is:

$8\times2^{-(85-90)/5}=16\text{ hours}$

An 8-hour exposure therefore contributes $100(8/16)=50%$, shown as 50.0%, with 16.00 hours as the criterion time. Under NIOSH, the allowed time at 85 dB is 8 hours, so the same entered exposure is shown as 100.0% with 8.00 hours criterion time.

This side-by-side arithmetic demonstrates why the selected criterion must travel with the percentage. It does not determine which legal program applies.

Exposure-review checklist

1. Use calibrated, task-representative level and duration measurements.
2. Split materially different levels into separate entries.
3. Confirm the applicable workplace criterion before interpreting dose.
4. Keep the standard, every level, every duration, and the resulting percentage in the same record.
5. Escalate hearing-conservation and protective-equipment decisions to a qualified safety professional; this page does not select hearing protection or apply a noise-reduction-rating method.

For logarithmic sound arithmetic, see the decibel calculator, the sound level converter, and the room acoustics calculator.

Variable, impulsive, and non-occupational noise can require methods not represented here. A few entered periods may not represent a full shift or changing exposure pattern.

Sources

• OSHA, 29 CFR 1910.95 Occupational Noise Exposure — OSHA criterion and dose framework.

• NIOSH, About Occupational Hearing Loss — NIOSH recommended criterion and prevention context.

• 98 126 — NIOSH Criteria for a Recommended Standard: Occupational Noise Exposure (DHHS (NIOSH) Publication 98-126): the 85 dBA criterion and 3 dB exchange rate behind the NIOSH allowed-time formula.