The method
Before using the result
- NIOSH recommended exposure limit model: 85 dBA criterion, 3 dB exchange rate and 80 dBA threshold. This is not the OSHA 90 dBA/5 dB model. Supply measured periods for the assessed day.
Worked examples
These original training examples illustrate the method for Certified Industrial Hygienist (CIH). Use the matching “Load example” button above to explore a variation; example values are not equipment settings or prescribed criteria.
1. Worked example
Combine task-based measured noise periods under one explicitly stated NIOSH model. Recognise why the same readings can produce a different result with OSHA dosimeter settings.
Supplied niosh exposure periods
| A-weighted level (dBA) | Exposure duration (h) |
|---|---|
| 85 | 4 |
| 88 | 2 |
- NIOSH allowable hours = 8 × 2^((85 − dBA)/3).
- Sum measured duration/allowable duration; periods below 80 dBA are excluded under the stated threshold.
- NIOSH daily dose: 100 %
- Recorded exposure time: 6 h
Do not mix OSHA or other dosimeter settings into this NIOSH calculation.
2. Comparison example
Compare a different supplied condition using the same method. For Safety Conquer, the important check is that the input meaning, units and method assumptions still match the problem.
Supplied niosh exposure periods
| A-weighted level (dBA) | Exposure duration (h) |
|---|---|
| 85 | 8 |
- NIOSH allowable hours = 8 × 2^((85 − dBA)/3).
- Sum measured duration/allowable duration; periods below 80 dBA are excluded under the stated threshold.
- NIOSH daily dose: 100 %
- Recorded exposure time: 8 h
Do not mix OSHA or other dosimeter settings into this NIOSH calculation.
Check your understanding
1. What dose results from 8 hours at 85 dBA?
100% under the NIOSH model used here.
2. What happens to allowable duration when level rises by 3 dB?
It halves; 88 dBA corresponds to 4 hours at 100% dose.
3. Can this result be labelled an OSHA noise dose?
No. OSHA and NIOSH settings are different; the method is explicitly NIOSH.
Continue with the matching exam topic
This tool connects to Certified Industrial Hygienist (CIH) free practice. Work through a question independently, then use the calculation steps to identify where your method differs. The tool stays free whether or not you choose paid preparation.