Noise and vibration
Noise, is unwanted sound that may damage a person's hearing. The amount of damage caused by noise depends on a number of things, including:
- how much noise is received over a period of time
- the noise intensity or loudness
- the noise frequency or pitch
- the duration and pattern of exposure
- each person¿s susceptibility to hearing damage.
In the abrasive blasting industry, causes of noise include:
- release of compressed air at the blast nozzle and pot blow-down
- feed air into a protective helmet
- air compressors
- ventilation systems
- blast cabinets
- truck and crane noise.
Maximum noise levels up to 137 dB(A) and peak levels up to 145 dB(A) have been measured during blasting activities at the operator position when the abrasive material runs out. In-helmet feed air noise levels up to 102dB(A) have also been measured during abrasive blasting.
Regular exposure to high levels of noise causes hearing loss through the destruction in our inner ears. There is no cure for hearing loss and the damage done is therefore permanent! Often there is also another effect, the ringing in the ears (tinnitus) accompanying the hearing loss.
Noise exposure exceeding an average level of 85dB(A) over an 8 hour work period (LAeq.8h 85dB(A)), or an instantaneous noise such as from a sudden air release or impact, exceeding 140dB(C) presents a high risk to a persons health and safety at the workplace. A person working with or near noisy equipment or processes may be affected by high direct or ambient noise and develop noise induced hearing loss, where no control measures have been put in place.
More information on noise is provided in hazards of abrasive blasting section of the Abrasive Blasting Industry Code of Practice 2004.
Abrasive blasters are subject to hand-arm vibration from the force of the abrasive moving through the blast hose and nozzle.
Prolonged use of abrasive blasting equipment may lead to a condition known as vibration white finger (VWF) or dead finger or Raynaud's phenomenon. It results from persistent microscopic damage to nerves and blood capillaries in the fingers and hand.
In the early stages the effects are reversible, however, chronic exposure may result in gangrenous and necrotic changes in the fingers. There is no effective treatment to reverse these effects.
More information on vibration is provided in general hazards section of the Abrasive Blasting Industry Code of Practice 2004.