Indicators can be defined from different perspectives, reflecting different worldviews and value systems.  Amongst others, indicators may be based on the following perspectives:

• Utilitarian – focused on the overall (total or net) impacts across the population as a whole
  • e.g. average exposure; total mortality; total monetary cost; total disease adjusted life years;
• Normative – focused on the degree to which predefined targets and goals are being met
  • e.g. percentage of population above the air quality standard; excess mortality above the policy target;
• Equity – focused on inequalities in exposures or health risks between different, definable sub-populations, typically delimitated in terms of  socio-economic status, gender, ethnicity or age
  • e.g.  ratio of attributable mortality rate in low to high socio-economic groups;
• Public perception – focused on the acceptability of, or attitudes towards, conditions by the general public
  • e.g. percentage of people concerned about air quality conditions.

Different stakeholders often have different worldviews, so care is needed in focusing on only one of these perspectives, since this may bias the assessment towards particular stakeholder groups.  In many cases, therefore, a mix of indicators, reflecting different perspectives, may be appropriate.