It is expressed in decibels, it is all around us and usually unpleasant. Noise is one of the risks that are not obvious at first but can cause severe and lasting consequences. As much as 85 decibels can damage the auditory apparatus in the case of long-term exposure.
Sound or noise?
Sound is a vibration of a flexible environment in the frequency range of normal human hearing - 20 Hz to 20 kHz. It spreads by means of sound waves.
Noise is an unwanted sound that creates an unpleasant or disturbing impression. This effect is subjective (even the ticking of an alarm clock can be disturbing) as well as objective (measurable hearing damage). It is measured in decibels (dB).
Government Regulation No. 272/2011 Coll. lays down non-exceedable hygienic noise and vibration limits for the following noise:
- Impulsive. Noise generated by an impulse or a sequence of impulses. Its sources may be, for example, explosions in quarries and mines, demolition or firearms.
- Stable. The level of steady noise does not change by more than 5 dB over time.
- Variable. The level of variable noise changes by more than 5 dB over time.
What are the risks?
The longer you are exposed to excessive noise, the greater the risk of hearing damage. The worst stage is total hearing loss. The risk is not only for employees working with the machine but often for other people in the vicinity.
For those who already have slightly damaged hearing, the risk may be even greater and often deteriorate rapidly. Moreover, worse communication due to excessive noise in the workplace can lead to accidents. The general rule is that if it is not possible to communicate normally at a 1-meter distance, the noise level is too high.
Noise is more or less present in almost all workplaces, whether in agriculture, production, warehouses, the textile industry, mines, at construction sites or metal or wood processing sites. The most common sources of excessive noise are:
- heavy machinery,
- transportation of materials in the workplace by trucks,
- power tools,
- production belts,
- pneumatic tools,
- or ventilation.
How to measure the risk
The risk for employees starts at 80 dB. Deafness can occur from 90 dB. However, it is not only the intensity that matters. The risk assessment of excessive noise depends on several factors:
- duration of noise exposure,
- distance from the source,
- sound frequency and pitch,
- other factors, such as age, diseases, genetics, etc.
When the level of excessive noise is exceeded, every 3-decibel increase halves the maximum permissible time of the employees' exposure to this noise.
It is difficult to determine a safe noise level, because it is different for everyone. However, the general rule is that values above 80 dB can cause hearing damage in the case of long-term exposure (more than 8 hours). 100-decibel noise can damage hearing after just 15 minutes.
Above 130 dB, the noise becomes painful. Values above 140 dB cause an acoustic trauma.
The World Health Organization recommends the following workplace noise levels:
closed office: 30-40 decibels.
open office: 35-40 decibels.
Laboratories in normal operation: 35-50 dB.
Control stations: 35-55 dB.
Production halls: 65-70 dB.
Healthcare: 30-45 dB.
The symptoms and consequences may vary
Once you have been exposed to excessive noise for a long time, problems can occur quickly. You can learn that something is wrong from the following symptoms:
- ringing in the ears,
- loss of the ability to hear higher-pitched sounds,
- feeling of muffled hearing,
- poor hearing of distance or group conversations,
- need to increase the TV or radio volume,
- mishearing the telephone or the doorbell,
- trouble determining which direction the sound comes from,
- increased need for concentration when listening,
- increased stress due to poor understanding of the surroundings.
The consequences can be both auditory and non-auditory.
- Auditory consequences - acoustic trauma (consequence of highly impulsive noise) or bilateral sensorineural hearing loss (consequence of long-term exposure to intense noise)
- Non-auditory consequences - side effects such as emotional balance disorders and general irritability, sleep disorders, chronic fatigue, decreased immunity, cardiovascular disease (high blood pressure), stress-related and psychosomatic diseases, increased rate of accidents.
Assess risks and protect yourself
First, you need to identify employees who are at risk of hearing loss and define how long they are daily exposed to noise. Before choosing protective equipment, however, try to reduce the risk of noise as much as possible.
- Create a workplace layout.
- Use work procedures that do not produce as much noise.
- Equip employees with tools that emit as little noise as possible.
- Reduce noise by technical means - sound-proof covers, noise screens, anti-noise booths, special materials that absorb sound waves.
- Limit the duration of workers' exposure to high noise levels.
- Observe the correct work and rest schedule.
According to the law, the employer must provide the employees with PPE already at 80 dB. From 85 dB up, the employer is also obliged to make sure PPE is used.
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