I agree with Clark, the AAT needs to be specific to the workplace (as well as doing the general background and health risk explanations). What building material/surface will they work on, what tools, what other dusts or fibres might they need to distinguish, are they using drills, saws. Sweeping etc? Do you have samples to show to the staff? If you are so vague I think you need a consultant/advisor if you don't have the knowledge.