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Engineering ToolBox > Daily Noise Dose Level
When the daily noise exposure consists of periods of different noise levels, the daily dose can be calculated as:
D = ( te1 / td1 + te2 / td2 + ... + ten / tdn ) 100% (1)
where
D = daily noise exposure (%)
te = exposure time at a specified noise level
According the National Institute for Occupational Safety - NIOSH - the daily dose level - D - should not equal or exceed 100.
The daily dose can be converted to an 8-hr Time-Weighted Average -TWA by the formula
TWA = 10 log( D / 100 ) + 85 (2)
Daily noise dose as an 8-hr TWA for different daily noise doses:
| Daily Noise Dose (%) | 8-hr TWA (dBA) |
| 20 | 78.0 |
| 30 | 79.8 |
| 40 | 81.0 |
| 50 | 82.0 |
| 60 | 82.8 |
| 70 | 83.5 |
| 80 | 84.0 |
| 90 | 84.5 |
| 100 | 85.0 |
| 200 | 88.0 |
| 400 | 91.0 |
| 600 | 92.8 |
| 800 | 94.0 |
| 1,000 | 95.0 |
| 1,500 | 96.8 |
| 2,000 | 98.0 |
| 4,000 | 101.0 |
| 6,000 | 102.8 |
| 8,000 | 104.0 |
| 10,000 | 105.0 |
| 20,000 | 108.0 |
| 40,000 | 111.0 |
| 60,000 | 112.8 |
| 80,000 | 114.0 |
| 100,000 | 115.0 |
| 150,000 | 116.8 |
| 200,000 | 118.0 |
| 400,000 | 121.0 |
| 600,000 | 122.8 |
| 800,000 | 124.0 |
| 1,000,000 | 125.0 |
| 2,000,000 | 128.0 |
| 4,000,000 | 131.0 |
| 6,000,000 | 132.8 |
| 8,000,000 | 134.0 |
| 10,000,000 | 135.0 |
| 20,000,000 | 138.0 |