One approach to determi- nation of the number of sites would be to address it in a manner similar to that of ISO 14644-1 for the walls and floors (as relevant). Each surface would then be treated as a separate item and the minimum number of sites determined for each. While this might work for walls and floors, the number of surface sampling sites for equipment remains unanswered and is not notice- ably amenable to this approach. This, quite frankly, may well be something that must be left to determination at each individual site—the numbers could be driven by the nature of the equipment and the associated manu- facturing process.