2.4 Hearing and respiratory protection basics

1 The construction noise limits

29 CFR 1926.52(a) requires protection against the effects of noise exposure when sound levels exceed those in Table D-2, measured on the A-scale at slow response. The permissible exposure runs on a 5 dB exchange rate: every 5 dB increase halves the time you may be exposed.

Three more provisions complete the picture. 1926.52(b): where levels exceed the table, feasible administrative or engineering controls shall be used first, and PPE only if those controls fail to bring exposure within the table — the hierarchy of controls, written into the standard. 1926.52(d)(1): where levels exceed the values, a continuing, effective hearing conservation program shall be administered. And 1926.52(e): exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

When the day is made of several noise levels, the standard combines them with the equivalent noise exposure factor in 1926.52(d)(2)(ii): add each period's actual time divided by the permitted time at that level, and if the total exceeds 1, the exposure is over the limit. Our noise exposure and TWA calculator does that arithmetic and also shows the NIOSH recommended limit, which uses 85 dBA and a 3 dB exchange rate and is substantially more protective.

2 Recognizing a noise problem without a meter

A rough field indicator: if you have to raise your voice to be understood by someone an arm's length away, you are probably somewhere around 85 dBA or above. Common construction sources sit well past that — chipping hammers, powder-actuated tools, masonry saws, jackhammers, and the generator you stand next to all day.

The warning signs of overexposure are ringing in the ears after the shift and a temporary muffled feeling that clears by morning. Those are not harmless; they are the sound of hair cells that will not all recover. Noise-induced hearing loss builds silently at 4,000 Hz first, which is why the first thing people lose is consonants in conversation, not volume.

3 Hearing protectors and the NRR

29 CFR 1926.101 is short. Where it is not feasible to reduce noise levels or exposure durations to the Table D-2 values, ear protective devices shall be provided and used (a). Devices inserted in the ear shall be fitted or determined individually by competent persons (b). And plain cotton is not an acceptable protective device (c).

Every protector sold in the United States carries a Noise Reduction Rating in decibels, from a laboratory test. You do not get that number on a jobsite. OSHA's own method, in Appendix B of 1910.95, derates the labeled NRR by 7 dB when applying it to an A-weighted measurement, and OSHA also applies a 50 percent safety factor when deciding whether engineering controls are needed. NIOSH goes further, recommending derating by 25 percent for earmuffs, 50 percent for formable foam earplugs, and 70 percent for other earplugs, because real-world fit is nothing like the laboratory. Our NRR derating calculator shows all of those methods side by side.

Fit is everything. A foam plug that is not rolled down thin and inserted deep enough gives a fraction of its rating; a muff whose cushion crosses the arm of your safety glasses leaks. NIOSH's current position on hearing protector selection favors individual fit testing to obtain a personal attenuation rating over generic derating — if your employer offers it, take it.

4 What is actually in the air

Construction dust is not one hazard. Respirable crystalline silica comes from cutting, grinding, drilling and demolishing concrete, brick, block and stone, and causes silicosis, lung cancer and kidney disease; it is regulated by 29 CFR 1926.1153, whose Table 1 lists specified control methods — water delivery, local exhaust with a HEPA vacuum, enclosed cabs — with the respiratory protection required for each task and duration. Asbestos and lead live in pre-1980s buildings and have their own construction standards, 1926.1101 and 1926.62. Welding fume, engine exhaust, isocyanates in spray foam and coatings, and solvent vapors each need their own answer.

The first rule of all of them is not the respirator. 29 CFR 1910.134(a)(1) — which applies to construction identically through 1926.103 — states that the primary objective shall be to prevent atmospheric contamination, accomplished as far as feasible by accepted engineering control measures such as enclosure, ventilation, and substitution of less toxic materials. Respirators come in when engineering controls are not feasible or while they are being installed. On a silica task, that means the saw runs wet, or with a shroud and a HEPA vacuum, before anyone talks about a mask.

5 The respirator rules that apply the moment a mask is required

A respirator is the most heavily regulated piece of PPE on the site, because a mask that does not seal gives false confidence. When respirators are necessary — or whenever the employer requires them — 1910.134(c)(1) requires a written respiratory protection program with worksite-specific procedures, administered by a trained program administrator. From that program flow the three requirements you will personally experience:

1. 1
   Medical evaluation first (1910.134(e)(1)): the employer must provide a medical evaluation of your ability to use a respirator before you are fit tested or required to wear one. Breathing through a filter is work for the heart and lungs.
2. 2
   Fit testing (1910.134(f)(2)): anyone using a tight-fitting facepiece must be fit tested before first use, whenever a different facepiece size, style, model or make is used, and at least annually — plus again after facial scarring, dental changes, or an obvious change in body weight.
3. 3
   No facial hair in the seal (1910.134(g)(1)(i)(A)): the employer shall not permit a tight-fitting facepiece to be worn by an employee with facial hair that comes between the sealing surface and the face, or that interferes with valve function. This is physics, not grooming policy — a day of stubble measurably breaks the seal.

Also worth knowing: a user seal check every time you put it on, filters and cartridges changed on a schedule set by the program, and the difference between a NIOSH-approved filtering facepiece such as an N95 and a loose surgical or nuisance dust mask, which is not respiratory protection at all. Where respirator use is genuinely voluntary, Appendix D of 1910.134 is the information the employer must give you before you wear one anyway.

6 Building the habit

Hearing and lungs are the two areas where the consequence arrives twenty years after the exposure, so nothing on the jobsite pushes you to protect them today. The crews who still hear well at sixty made a few small decisions repeatedly: they wore protection for the whole loud task rather than most of it, they moved the noisy machine instead of standing next to it, they hooked the vacuum shroud to the grinder even though it was slower, and they took the annual hearing test seriously enough to notice a shift.

If your employer runs a hearing conservation program, your audiogram is the only early warning you will get. A standard threshold shift on that test is not paperwork; it is a measurement telling you the current controls are not working.