Administrative controls and hearing conservation programs

Engineering controls are the best answer to noise, but in many workplaces they cannot bring every exposure below the limit, at least not right away. What remains has to be managed through administrative controls, hearing protectors and the systematic checks that make sure protection is working. These pieces come together in a hearing conservation program, also called a hearing loss prevention program. This lesson covers administrative controls, the elements of a sound program, the roles involved and how to tell whether the program is actually preventing hearing loss.

Administrative controls

Administrative controls change the way work is organized to reduce the time workers spend in noise or the number of workers exposed. They depend on planning and supervision, so they rank below engineering controls, but they are often quick to introduce.

Job rotation deserves a careful look, because it is often proposed as a cheap fix. With a 3 dB exchange rate, rotation can bring each worker under the limit, but it does so by sharing the dose, not reducing it, and the numbers can be disappointing at high levels.

import math

def lex8(segments):
    """segments: list of (hours, dBA) for one worker in an 8-hour day."""
    return 10 * math.log10(sum(h * 10 ** (L / 10) for h, L in segments) / 8)

station, elsewhere = 97, 80
print(f"One worker at the {station} dBA station all day: {lex8([(8, station)]):.1f} dBA")
for n in [2, 4, 8]:
    h = 8 / n
    L = lex8([(h, station), (8 - h, elsewhere)])
    print(f"Rotate among {n} workers ({h:.1f} h each at the station): {L:.1f} dBA each")

One worker at the 97 dBA station all day: 97.0 dBA
Rotate among 2 workers (4.0 h each at the station): 94.1 dBA each
Rotate among 4 workers (2.0 h each at the station): 91.2 dBA each
Rotate among 8 workers (1.0 h each at the station): 88.5 dBA each

Even with eight workers sharing the station, each spends an hour at 97 dBA and receives a Lex,8 of about 88 dBA, still over the limit. Rotation helps only when the noisy station is moderately loud. It also brings more people into the hearing conservation program, and if the noise is above about 100 dBA, minutes of unprotected exposure can be enough to exceed the daily allowance. Rotation is a supplement to engineering controls and protectors, not a substitute.

What a hearing conservation program is

A hearing conservation program is the set of activities that keep workers' hearing from being damaged where noise cannot be fully controlled. The terms used vary, but the core elements are the same everywhere.

Roles and responsibilities

Programs fail most often because nobody owns them. Purchasing buys earplugs, a contractor runs the mobile hearing test van once a year, and nobody looks at whether the results are getting worse. A strong program assigns clear responsibilities.

Signs and noise zones

Ontario requires signs at each approach to areas where noise regularly exceeds 85 dBA where practicable, and other provinces have similar rules. Signs should state clearly that hearing protection is required, ideally with a pictogram, and should be placed at the boundary of the zone shown on the noise map from Lesson 4. Many employers also mark noisy machines individually, especially where a machine is loud only when a particular operation is running.

Zone rules need to be simple and consistent: everyone entering the marked area wears hearing protection, including managers, visitors and contractors, even for a short time. Inconsistent rules, such as protectors being required only when a certain machine is running, are hard to follow and easy to ignore. Where levels change a lot, consider electronic signs that light up when a machine runs.

Training that changes behaviour

Training is required in both countries, but the quality of training varies enormously. Lectures about decibels followed by a signature on a form do little. Training that changes behaviour tends to share some features.

Hearing protection policy

The program should state which protectors are approved for which areas and tasks, how workers obtain replacements, and how special needs are handled: workers with existing hearing loss, workers who need to hear alarms or radio communication, workers who wear safety glasses or other headgear, and workers with ear conditions. It should offer a choice of at least a few types and sizes, because comfort strongly predicts consistent use. Lessons 8 and 9 cover selection and fitting in detail.

Program evaluation

A hearing conservation program exists to prevent hearing loss, so the ultimate measure of success is whether workers' hearing stays stable. Program evaluation looks at both processes and outcomes.

Audiometric database analysis compares groups of workers over time. If exposed workers show significantly more threshold shifts than would be expected from ageing, or more than a comparison group with low exposure, the program is not working. A practical approach is to calculate the percentage of tested workers with a significant shift each year, by department or job group, and investigate groups that stand out. Guidance from NIOSH and the American National Standards Institute describes formal methods based on how much hearing levels vary between successive tests.

# Annual audiometric results by department: (workers tested, workers with a
# significant threshold shift). Illustrative data for program evaluation.
depts = {
    "Press shop": (64, 7),
    "Assembly": (110, 3),
    "Maintenance": (28, 4),
    "Shipping": (45, 1),
    "Office (comparison)": (40, 0),
}
total_t = sum(t for t, _ in depts.values())
total_s = sum(s for _, s in depts.values())
print(f"Plant-wide shift rate: {100 * total_s / total_t:.1f} %")
for name, (tested, shifts) in depts.items():
    rate = 100 * shifts / tested
    flag = "  <- investigate" if rate > 5 else ""
    print(f"  {name:<20} {shifts:>2}/{tested:<3} {rate:5.1f} %{flag}")

Plant-wide shift rate: 5.2 %
  Press shop            7/64   10.9 %  <- investigate
  Assembly              3/110   2.7 %
  Maintenance           4/28   14.3 %  <- investigate
  Shipping              1/45    2.2 %
  Office (comparison)   0/40    0.0 %

Here the plant-wide figure hides large differences: the press shop and maintenance stand out. Those departments should be investigated: are exposures higher than assessed, are protectors suitable and worn, are workers trained, or is something else, such as leisure noise or testing quality, involved? The threshold used to flag groups, 5 per cent in this example, is a program choice, not a legal limit.

Records and confidentiality

Programs generate several kinds of records: noise assessments and maps, control plans, protector issue and selection records, training records, audiometric results and follow-up actions, and program evaluations. Audiometric results are personal health information. They should be held by the testing provider or a health professional, shared with the worker, and shared with the employer only to the extent needed for the program, usually as summaries and notices of significant shifts. Committees should see aggregate data, not individual audiograms.