The Framework

Occupational hygiene is usually described in four stages, and the order matters as much as the content.

• Anticipate. Identify health hazards before they are introduced — at design, procurement and process change. Substituting a solvent at specification stage costs nothing; controlling it for twenty years costs a great deal.
• Recognise. Identify hazards present in existing work — by walk-through survey, process knowledge, safety data sheets and by talking to the people doing the job.
• Evaluate. Determine the exposure — by measurement, modelling or comparison with similar work — and compare it against limits and action levels.
• Control. Reduce exposure using the hierarchy, and verify that the control works.

The walk-through survey

The basic tool of recognition is a structured walk-through: follow the material from delivery to disposal, note every point at which it is transferred, heated, cut, mixed, cleaned or spilled, and note where people stand relative to each of those points. Most exposure occurs at transfers and at cleaning, not during the main process.