A jackhammer runs about 102 dBA, a concrete saw or grinder 98, a nail gun 97, a bulldozer 100 — all figures published by OSHA. The number that matters, though, is not how loud the tool is but how long you stand next to it: at 102 dBA federal OSHA allows about an hour and a half a day, and NIOSH allows nine minutes.
Jobsite sound levels, and the time that goes with them
Every level below comes from the Sound Level Chart on page 7 of OSHA 3498, Protecting Yourself from Noise in Construction. OSHA attributes the underlying measurements to ANSI/ASSE A10.46-2007, to the AIHA reference The Occupational Environment (2nd ed., 2003), and to the University of Washington's Noise and Hearing Loss Prevention in the Construction Industry (2004). Nothing has been added to the list, and nothing has been rounded.
The two time columns are computed, not quoted. The OSHA column is the reference duration from Table G-16 and the OSHA Technical Manual: T = 8 / 2^((L − 90)/5). The NIOSH column uses the 85 dBA criterion and 3 dB exchange rate of NIOSH 98-126: T = 8 / 2^((L − 85)/3). Both answer the same question — how long at this level alone uses up a full day's allowance.
| Equipment | Sound level (dBA) | OSHA permitted duration | NIOSH allowable duration |
|---|---|---|---|
| Chain saw | 110 | 30 min | 1.5 min |
| Grader, scraper | 107 | 45 min | 3 min |
| Jackhammer | 102 | 1 h 31 min | 9 min |
| Bulldozer | 100 | 2 h | 15 min |
| Concrete saw, electric grinder | 98 | 2 h 38 min | 24 min |
| Nail gun | 97 | 3 h 2 min | 30 min |
| Forklift | 93 | 5 h 17 min | 1 h 16 min |
| Belt sander | 90 | 8 h | 2 h 31 min |
| Backhoe | 85 | 16 h | 8 h |
| Framing saw | 82 | 24 h 15 min | 16 h |
These are tool levels, not exposures. A shift is a series of levels and durations, and the 8-hour time-weighted average is what decides whether a hearing conservation program is required. Add your shift up with the noise exposure TWA calculator before concluding anything about compliance.
What those numbers sound like
Decibels are not intuitive, which is why every chart pairs jobsite levels with familiar ones. The everyday column of OSHA 3498 and Figure 3 of the OSHA Technical Manual, Section III Chapter 5 both do this; the values below are theirs.
| Sound | Level (dBA) | OSHA source |
|---|---|---|
| Threshold of hearing | 0 | 3498 / OTM Fig. 3 |
| Whispered voice | 30 | OSHA 3498 |
| Soft whisper, 5 ft away | 40 | OTM Figure 3 |
| Urban residence | 50 | OTM Figure 3 |
| Normal conversation | 60 | OSHA 3498 |
| Classroom chatter | 70 | OTM Figure 3 |
| Schoolchildren in a noisy cafeteria | 80 | OSHA 3498 |
| Freight train, 100 ft away | 80 | OTM Figure 3 |
| Power lawn mower at the operator's ear | 90 | OSHA 3498 |
| Boiler room | 90 | OTM Figure 3 |
| Wood shop | 100 | OSHA 3498 |
| Construction site | 100 | OTM Figure 3 |
| Night club with music | 110 | OTM Figure 3 |
| Snowmobile | 120 | OSHA 3498 |
| Operating heavy equipment | 120 | OTM Figure 3 |
| Jet taking off, 200 ft away | 130 | OTM Figure 3 |
| Jet engine at takeoff, gunshot | 140 | OSHA 3498 |
| Threshold of pain | 140 | OTM Figure 3 |
Two things stand out. The jobsite table starts where the everyday one gets uncomfortable — a framing saw at 82 dBA is already louder than a noisy cafeteria. And 140 dBA appears twice, as a jet engine and as the threshold of pain; it is also the peak sound pressure level that OSHA says impulsive or impact noise should never exceed.
Why two charts disagree about the same tool
OSHA lists a chain saw at 110 dBA in the construction pocket guide. OSHA also states, in its sawmills eTool, that chain saws "typically are measured at 125 decibels (dBA)" and heavy equipment at 95 to 110 dBA. Fifteen decibels apart, same agency, same tool.
Neither figure is wrong. A sound level is a measurement at a place, under conditions, and a chart rarely states either. Four things move the number:
- Distance. The single biggest factor. In the open, a point source drops about 6 dB every time the distance doubles, so the same saw reads 110 dBA at the operator's ear and far less at the next trade over.
- What the tool is doing. OSHA's own chart separates a chain saw from a chain saw accelerating. Cutting hardwood, cutting nothing and idling are three levels.
- What the sound bounces off. Indoors, or in a stairwell, or between two concrete walls, reflected sound adds to the direct sound and the level stops falling off with distance.
- Maintenance and accessories. OSHA's guide is explicit that seals, lubrication, sharp blades and bits, and mufflers change the level significantly.
The practical rule: use a chart to plan and to argue for controls, and use a meter or a dosimeter to decide anything about compliance. If you want to see what distance does to a published level, put the number and its distance into the noise distance attenuation calculator.
How long OSHA allows at each level
The time columns in the first table come from OSHA's exchange rate: under federal OSHA, every extra 5 dBA cuts the allowed time in half. That is why the numbers fall off a cliff on a jobsite — three decibels of extra noise sounds like nothing and costs you a third of your day.
| Duration per day (hours) | Sound level (dBA, slow response) |
|---|---|
| 8 | 90 |
| 6 | 92 |
| 4 | 95 |
| 3 | 97 |
| 2 | 100 |
| 1½ | 102 |
| 1 | 105 |
| ½ | 110 |
| ¼ or less | 115 |
The 90 dBA permissible exposure limit is an 8-hour average, not a ceiling. The 85 dBA action level (29 CFR 1910.95(c)(1)) is the number that triggers the hearing conservation program — monitoring, annual audiograms, hearing protectors and yearly training. NIOSH recommends 85 dBA as the limit itself, with a 3 dB exchange rate.
Notice what that means for the tools in the chart. Six of the ten items on OSHA's own construction list are loud enough to consume a full day's allowance in under three hours.
Two tools at once
Levels do not add arithmetically. Two 90 dBA saws in the same bay give 93 dBA, not 180. The equation OSHA publishes in Appendix B.3 of the Technical Manual is L_total = 10 × log₁₀(10^(L₁/10) + 10^(L₂/10) + …), and OSHA also gives the shortcut for doing it in your head:
| Difference between the two levels | Add this to the higher level |
|---|---|
| 0–1 dB | 3 dB |
| 2–4 dB | 2 dB |
| 5–9 dB | 1 dB |
| 10 dB or more | 0 dB |
The last line is the useful one. A 102 dBA jackhammer and a 90 dBA belt sander are 12 dB apart, so the sander adds nothing measurable — quieting it changes nothing while the hammer runs. Controls have to reach the loudest source first, and usually more than one.
No meter? Use OSHA's arm's-length test
OSHA publishes a screening check for exactly this situation, and it takes five seconds. Stand about an arm's length from a coworker. If you have to raise your voice to be heard 2 to 3 feet away, assume the sound level is at or above 85 dBA.
That is not a measurement and it does not satisfy the monitoring requirement of 29 CFR 1910.95(d). What it does is settle the question of whether the site deserves a real survey — and on most active jobsites, the answer is yes.
What to do with a loud number
OSHA's construction noise guide frames the fix as three steps, in order:
- Reduce it. Use the quietest equipment available for the task — a smaller generator, a sharper blade, a properly maintained muffler. OSHA's Technical Manual reports a case where replacing the bearings on a 20-ton press and restoring proper lubrication cut noise levels by 7 to 16 dBA.
- Move it. Push the source away with extension cords, longer air hoses and longer welding leads, or face it away from the crew. Six decibels per doubling of distance is free attenuation.
- Block it. Build a barrier from plywood or on-site material, or box in a generator with absorbing material inside the box.
Only after that does hearing protection come in — and it is worth less than the package says. OSHA derates the labeled Noise Reduction Rating before crediting it against your exposure, which is why the number on the box and the protection at the eardrum are different things. Run yours through the hearing protector NRR calculator.
Bottom line
- OSHA's own construction chart runs from a framing saw at 82 dBA to a chain saw at 110 dBA, with jackhammers at 102 and grinders at 98.
- A level without a duration means nothing: 102 dBA is an hour and a half under federal OSHA, and nine minutes under the NIOSH criteria.
- Charts disagree because levels depend on distance, task, surroundings and maintenance. Plan with a chart, decide with a meter.
- 85 dBA as an 8-hour average triggers the hearing conservation program; 90 dBA is the permissible exposure limit and requires feasible controls above it.
- If you have to raise your voice to be heard three feet away, treat the area as 85 dBA or more until it is measured.