A global ESB system-especially if coordinated with a global monitoring system-can serve as a safety net to verify earlier forecasts and provide for adjustments and determine the adequacy of actions that can be taken to prevent or remedy serious chemical impacts. But the full potential of ESB can only be fully realised if the samples banks contents are directly comparable, i.e. if they are established and maintained according to well-defined guidelines. In other words not only can ESBs be extremely useful as a practical approach to a number of aspects of harmonization of environmental measurement, they themselves also require harmonization.