Demolition noise control
Demolition noise control overview
There was considerable concern for many years over the increasing cases of occupational deafness and this led to the introduction of the Noise at Work Regulations in 1998 and the revised Control of Noise at work regulations in 2005. The HSE has estimated that an additional 1 . 1 million workers will be covered by the revised Regulations.
These Regulations, require the employer to:
- Assess noise levels and keep records
- Reduce the risks from noise exposure by using engineering controls in the first instance and the provisions and maintenance of hearing protection as a last resort
- Provide employees with information and training
- If a manufacture or supplier of equipment ( particularly if any of the three action levels is likely to be reached )
Many occupations have potential noise problems including demolition, construction, manufacturing, entertainment, the uniformed services and call centres.
The main purpose of the Noise Regulations is to control noise levels rather than measuring them. This involves the better design of machines, equipment and work processes, and ensuring that personal protective equipment is correctly worn and employees are given adequate training and health surveillance.
Sound is transmitted through the air by sound waves, which are produced by vibrating objects. The vibrations cause a pressure wave which can be detected by a receiver, such as a microphone or the human ear. The ear may detect vibrations which vary from 20 to 20,000 (typically 50-16,000) cycles each second (or Hertz – Hz) Sound travels through the air at a finite speed ( 342 m/s). The existence of this speed is shown by the time lag between lightening and thunder during a thunderstorm. Noise normally describes loud, sudden, harsh or irritating sounds although noise is defined as any audible sound.
Noise may be trasmitted directly through the air, by reflection from surrounding walls or buildings or through the structure of a floor or building. In demolition work, the noise and vibrations from a pneumatic drill will bee transmitted from the drill itself, from the ground being drilled and from the walls of surrounding buildings.
Health impact of noise in demolition
Noise can lead to ear damage on a temporary (acute) or permanent (chronic) basis.
- Temporary threshold shift – caused by short excessive noise exposures and affects the cochlea by reducing the flow of nerve impulses to the brain. The result is a slight deafness, which is reversible when the noise is removed.
- Tinnitus – a ringing in the ears caused by an intense and sustained high noise level. It is caused by the over-stimulation of the hair cells. The ringing sensations continues for up to 24 hours after the noise has ceased.
- Acute acoustic trauma – Caused by a very loud noise such as an explosion. It affects either the eardrum or the bones in the middle ear and is usually reversible. Severe explosive sounds can permanently damage the eardrum.
- Noise-induced hearing loss – Results from permanent damage to the cochlear hair cells. It affects the ability to hear speech clearly but the ability to hear is not lost completely.
- Permanent threshold shift– This results from prolonged exposure to loud noise and is irreversible due to the permanent reduction in nerve impulses to the brain. This shift is most marked at the 4000 Hz frequency, which can lead to difficulty in hearing certain consonants and some female voices.
- Tinnitus – is the same as the acute form but becomes permanent. It is a very unpleasant condition, which can develop without warning.
- Temporary deafness – can occur after leaving a noisy place. Hearing usually recovers within a couple of hours. This is a sign that continued exposure to loud noise could permanently damage your hearing.
- Sudden extremely loud noise can cause instant damage: and
- Repeated exposure causes gradual hearing loss over time. This is more common and it can take years for a worker to realise just how deaf they have become.
- Presbycusis is the term used for hearing loss in older people, which may have been exacerbated by occupational noise earlier in their lives