This document is intended to provide a guideline for grit/water (abrasive) blasting operations and the proper methods for reducing the hazards and risks associated with blasting activities.
This guiding principle covers:
- The hazards associated with blasting procedures.
- The requirements for blasting equipment.
- Procedural control measures (engineering and administrative).
Workers that carry out abrasive blasting face an increased risk of exposure to toxic dusts, high noise levels and vibration. All others who work in the vicinity of areas where abrasive blasting takes place, may also be at risk of exposure.
Exposure to dust/air contaminants is one of the primary hazards associated with abrasive blasting. Although the moisture during water blasting activities may reduce dust levels, the mists generated may still contain toxins (e.g. cleaning agents, oil, mud residues and disease organisms), which can lead to skin irritation, dermatitis, and asthma.
The main sources of the air contaminants include:
- The base material being blasted.
- The surface coating(s) being removed.
- The abrasive being used.
- Abrasive contamination from previous blasting operations.
Therefore, workers may be exposed to multiple hazards from both the abrasive and the surface being blasted. Additional air contaminants that may be present during blasting activities include: copper, iron, lead, aluminum, zinc. When consistently inhaled, these substances can lead to many long term illnesses, such as: increased blood pressure, fume fever, lung inflammation and lung/nasal cancer (See appendix 1).
Abrasive blasting produces noise levels that can cause permanent hearing loss in unprotected workers and others close to blasting operations. The main source of noise is the discharge of compressed air at the blast nozzle. Other noise sources include:
- The impact of the abrasive on the surface being blasted.
- Air compressors.
- Exhaust ventilation systems.
- The supply air inside the operator's helmet.
- Air released during grit pot blow-down/cleaning.
Small abrasive blasting cabinets are also sources of significant noise exposure for operators. The current permissible exposure limit (PEL) for noise is 85 dBA, with required action to be taken at 80 dBA. During blasting, noise levels usually range from 85 dBA to 145 dBA which can cause long term injury if no proper measures are taken.
Blasting operators may also be exposed to hand-arm vibration from the force of the abrasive moving through the blast hose. Prolonged use of abrasive blasting equipment can damage the nerves and blood vessels in the fingers, resulting in a condition known as hand vibration syndrome (also known as vibration white finger and Raynaud's disease).The signs and symptoms of hand vibration syndrome include: numbness, tingling, pale fingers, pain, and flushing. In severe cases, individuals lose their manipulative skills and the ability to distinguish between hot and cold objects. If exposure to vibration continues, skin necrosis and gangrene can occur.
- Only use certified and well maintained blasting equipment.
- Use barriers to isolate the blasting operations from other workers.
- Take measures to prevent the release of dust or contaminated water.
- All operators of blasting equipment should be competent and well instructed.
- Wear suitable PPE to prevent skin, eye, respiratory and ear injuries.