A relatively specific type of control banding was proposed in this BSI document. This suggested specific control approaches appropriate for various activities for four categories of nanomaterials.
Given the paucity of information available at the time that the BSI document was published, it was intended to provide a conservative approach, and gave strong recommendation that the efficacy of the chosen method should be evaluated.
To support this activity, the guidance also developed Benchmark Exposure Levels (BELs). These guidance values were not health-based, but again were intended to provide a conservative comparator.