Several years ago, at the request of Schiedam municipal authority and in collaboration with the Stimular Foundation, CE developed the Environmental Barometer, a tool for companies to measure the aggregate environmental impact of their operations (CE, 2000). The Barometer also yields insight into the environmental gains of specific environmental measures, allowing companies to weigh up alternative abatement options. The Environmental Barometer expresses a range of environmental impacts in terms of a common denominator, translating these impacts into monetary terms using shadow prices. This study, updating these shadow prices, was commissioned by the Stimular Foundation, fertiliser producers Thermphos B.V. and MKB Zeeland, the branch organisation for small and medium-sized businesses in the province of Zeeland.