OHS Canada Magazine

Turn down the volume: How industrial noise affects worker health

April 17, 2019

How loud is your plant? Conduct an assessment or employee survey to identify sources, gauge noise level, and who is exposed.

Industrial noise is more than just annoying and disruptive – it can cause permanent hearing damage. Exposure limits measured in decibels (dB) vary across Canada. In most jurisdictions, the limit is 85 dBA, but federally it’s 87 dBA, and 90 dBA in Quebec. Yet even without technical measurements there are certain signs that determine if there’s a noise problem in a plant:

Must voices be raised to be heard? After a shift, are ears ringing, and do people find they need to play car radios louder than on the way to work? After a few years, do employees find it hard to understand conversations at parties, restaurants or other crowded places?

Hearing issues include tinnitus (a ringing or buzzing in the ear) or temporary hearing loss that may improve over time in a quiet place, or permanent hearing loss. Permanent loss may occur in a person exposed to noise often, for long periods or at high frequencies.

Noise-induced permanent hearing loss worsens as long as the exposure continues. Initially, it’s most pronounced at a frequency of 4,000 Hz, but spreads across other frequencies over time and as the noise level increases. However, sometimes, just one short burst of extremely loud noise (such as a gunshot) can cause acoustic trauma that damages hearing. Other factors that affect hearing include vibration, the worker’s age, certain medications and diseases, and exposure to ototoxic chemicals, such as toluene and carbon disulfide.

Noise also has other health effects. Though difficult to pinpoint, researchers believe it may act as a general stressor that causes symptoms unrelated to hearing, such as high blood pressure, or changes to heart rate. A noisy environment also affects how a worker breathes and sleeps, and generally has a negative impact on physical and mental health.

Use controls
How noisy is your plant? Conduct an assessment or survey to determine the sources and the amount of noise, who is exposed, and for how long. The most obvious and effective solution is to use the hierarchy of controls. Where possible, eliminate the source of the noise.

The next best option is to control noise at its source by lowering it to acceptable levels with engineering controls. They substitute or modify the noise source or workplace environment by enclosing the noise source, adding acoustic soundproofing and using mufflers on equipment.

Administrative controls and the use of appropriate personal hearing protection also help. They involve rotating work schedules, or changing production schedules to keep noise exposure time within acceptable limits. Workers should wear appropriate personal hearing protection such as earmuffs or plugs, but only as an interim measure until noise is controlled at the source.

If monitoring noise levels are at an action level or above the legislated limit, develop and implement a hearing conservation program. Eight jurisdictions specifically require such a program when noise exceeds the occupational exposure limit (BC, Newfoundland and Labrador, PEI and federal jurisdictions), 85 dBA (Northwest Territories, Nunavut, Saskatchewan) or when there is excess noise (Alberta).

The hearing conservation program includes a policy and procedure. The CSA Standard Z1007 Hearing Loss Prevention Program Management recommends the following hearing conservation elements:

• Hazard identification and exposure monitoring
• Control methods (using the hierarchy of controls)
• Hearing protection devices (selection, use, and maintenance)
• Audiometric testing
• Hazard communication, education, and training
• Recordkeeping
• Continuous monitoring and improvement

All employers have a duty to provide a safe work environment and take all reasonable precautions to do so. Controlling noise is key to preventing work-related hearing loss.

The Canadian Centre for Occupational Health and Safety (CCOHS) in Hamilton contributed this article. CCOHS provides information, training, education, management systems and solutions that support health and safety programs and the prevention of injury and illness in the workplace. Visit www.ccohs.ca.

This article appeared in the June 2018 print version of AutoPlant.