Environmental indicators can be developed and used at a wide variety of geographic scales, from local to regional to national levels.” [1] “A parameter or a value derived from parameters that describe the state of the environment and its impact on human beings, ecosystems and materials, the pressures on the environment, the driving forces and the responses steering that system.
It can be considered, for example, that there are major subsets of environmental indicators in-line with the Pressure-State-Response model developed by the OECD.
Finally, there are indicators, such as the number of people serviced by sewage treatment, which track societal responses to environmental issues.
Criteria tend to focus on three key areas – scientific credibility, policy/social relevance and practical monitoring and data requirements.
These audiences are: 1) technical experts and science advisors, 2) policy-makers, decision makers and resource managers, and 3) general public and media.
The audience that includes policy-makers and resource managers will be concerned with using indicators that are directly related to evaluating policies and objectives.
[9][10] Individual indicators are designed to translate complex information in a concise and easily understood manner in order to represent a particular phenomenon (e.g. ambient air quality).
A number of methods have been devised in the recent past to boil down this information and allow for rapid consumption by those who do not have the time or the expertise to analyse the full set of indicators.