Indicator development describes methods to create and describe good indicators (that is, variables of special interest) in a risk assessment.
An indicator comprises a characteristic or condition which can be described or measured in a way which provides information about some other characteristic or condition which is, itself, not amenable to direct observation or measurement.
Environmental Health Indicators are usually numbers that represent a certain state of the environment, exposure, health state and/ or policy actions.
Working definition: An indicator is a variable that is of a particular interest, for example those that are reported in the risk assessment report.
- Airport environmental health indicators 
- WHO Environment and Health indicators 
- Variable attributes 
List of parents:
- Throughout the RA chain successive indicators / variables of specific interest are applicable
- Throughput indicators
- Source indicators
- Releases / Emission indicators
- Exposure indicators
- Health indicators
- Policy / Impact indicators