| Work activity | Typical level (dBA) | Example duration | Notes |
|---|---|---|---|
| Concrete breaking with powered hammer | 98 | 1 h | Short bursts still add significant dose. |
| Angle grinding steel | 92 | 2 h 30 m | Use shields, maintain discs, rotate tasks. |
| Dozer or loader operation | 88 | 3 h | Cab insulation and closed doors help. |
| Rebar tying with hand tools | 78 | 1 h 30 m | Often under threshold, but verify onsite. |
For each task with level L (dBA) and duration C (hours), the permissible time T (hours) is:
T = Tc × 2^((Lc − L) / ER)
Total dose fraction is the sum of C/T across all included rows:
Dose (%) = 100 × Σ(Ci / Ti)
The time‑weighted average level is computed from dose using the same exchange rate:
TWA (dBA) = Lc + ER × log2(Dose / 100)
- Pick a preset that matches your internal program.
- Confirm the criterion level, exchange rate, and duration.
- Set a threshold to ignore very low noise tasks.
- Enter each noisy task, level, and time onsite.
- Optionally include remaining time for full-shift estimates.
- Press Calculate dose to see results above.
- Download CSV for records, and PDF for reporting.
1) Why daily noise dose matters on projects
Construction work frequently combines multiple high‑noise tasks within one shift. Because dose is cumulative, several “short” exposures can exceed limits even when no single task lasts long. Dose planning helps prevent temporary threshold shifts, long‑term hearing loss, and compliance gaps during audits.
2) Typical sound levels seen on site
Real levels vary by tool condition, distance, and enclosures, but common ranges are informative for planning: concrete breaking and impact tools often sit near 95–105 dBA; grinding and cutoff saws commonly fall around 90–100 dBA; heavy equipment cabs may range 80–90 dBA depending on sealing and maintenance. A 10 dB increase represents a large jump in sound energy, so small measured changes can materially change permissible time.
3) What the calculator is actually summing
The calculator converts each task into an exposure fraction (C/T). Permissible time T depends on the selected criterion level and exchange rate. When the exchange rate is 3 dB, every 3 dB increase halves allowable time. When it is 5 dB, allowable time halves every 5 dB increase. Summing fractions gives a clear, defensible daily dose.
4) Presets and what they represent
The included presets support common program choices: a 85 dBA criterion level with a 3 dB exchange rate reflects a more protective approach; a 90 dBA criterion with a 5 dB exchange rate is less conservative; and an 85 dBA action‑trigger preset helps identify work needing controls even before the highest limit is reached. Your company procedures should determine which preset is used.
5) Interpreting dose and TWA together
Dose percent is the primary compliance indicator because it directly reflects the summed exposure fractions. TWA provides a single equivalent level for the selected shift length and exchange rate. A dose near 100% signals that engineered controls, administrative rotation, or stronger hearing protection are needed to keep workers within target limits.
6) Controls with measurable impact
Practical controls often produce measurable reductions: adding barriers, maintaining mufflers, using quieter tooling, and increasing distance can cut levels by several dB. Even a 3 dB reduction can double permissible time under a 3 dB exchange rate. Task sequencing also matters—moving the loudest work into shorter blocks reduces peak dose contributions.
7) Using the report for audits and toolbox talks
The CSV export supports recordkeeping and trend tracking across crews, tools, and work packages. The PDF export provides a clean summary for safety files, client documentation, and training. Save reports with the date, crew, location, and instrument method to strengthen traceability and support continuous improvement.
8) A practical planning example
If a worker spends 1 hour near 98 dBA concrete breaking and 2.5 hours near 92 dBA grinding, dose can rise quickly, especially under a protective exchange rate. Use the calculator to test “what‑ifs” such as reducing breaking time, swapping tooling, or enclosing the source, then confirm with real measurements onsite.
1) What is a noise exposure dose?
It is the cumulative exposure for a shift, calculated by summing each task’s time divided by its permissible time. A dose of 100% represents reaching the selected daily limit for your chosen standard.
2) Why do I see different results for different presets?
Presets use different criterion levels and exchange rates. A stricter exchange rate reduces permissible time faster as dBA increases, so the same task list produces a higher dose under a more protective preset.
3) What should I enter for sound level if I only have estimates?
Use conservative estimates until you can measure. Choose levels from similar tools and distances, then refine with meter or dosimeter readings. Saving both estimated and measured reports supports better planning and accountability.
4) Should I include remaining time?
Include remaining time when you want a full‑shift estimate. Set an assumed level that reflects typical background or quieter work. Excluding remaining time is useful when you only want to evaluate known noisy tasks.
5) Why are tasks below the threshold excluded?
The threshold prevents low‑level tasks from inflating calculations and focuses attention on meaningful noise contributors. You can lower the threshold if your program requires counting more of the shift’s sound environment.
6) Does hearing protection reduce the dose in this calculator?
The calculator reports dose based on measured or assumed environmental levels. To model protection, enter an effective reduced level after applying your protection method, but confirm with your safety program and fit testing approach.
7) What actions are recommended above 100% dose?
Prioritize engineering controls first, then administrative rotation and strict hearing protection enforcement. Reduce time at the loudest tasks, increase distance, add barriers or enclosures, and recheck the plan with fresh readings.