Many sceptics might argue that this is an apocalyptic view of the future that is unlikely to unfold. However, there are real environmental risks, even if the extent of them is debatable. In such a situation it seems appropriate to employ what is known as the precautionary principle. This involves taking action to prevent the worst type of scenarios unfolding. Just as overfishing requires legislation, quotas and legal action against those who break them, so might profligate environmental behaviour by the event industry. As has been noted elsewhere in this book, a considerable amount of environmental legislation already exists in many countries. In addition to this there are a number of industry standards, notably BS 8901 and ISO 20121, that have been discussed earlier in this book. The number of these standards is unlikely to decline. Given this, it is essential that the event industry is able to document its environmental performance and it is with this issue that the remainder of this chapter will be concerned. The focus of discussion will be on a relatively narrow range of environmental indicators. It is acknowledged that much of the discussion of sustainability indicators encompasses a range of social, economic and other factors that goes well beyond the purely environmental. However, the focus of this book is environmental and while the links with other factors are discussed, the environment remains the key factor.