ADLib Glossary (S)

Definition:

Significant effect

Many environmental assessments require the significance of an effect to be estimated. For example assessing if an activity have a ‘significant effect’ on a habitat?  There is no standard method for assessing or quantifying significance, very often it requires expert judgement and is often simply expressed as high, medium or low.  At a basic level it requires examining how an activity might affect an area by looking at what emissions it will produce (for example). The significance of these emissions/effects is related to a number of factors including sensitivity of the environment/habitat (receptor) to the emission and the magnitude of the emission. It may also take account of factors such as how reversible any damage is.  A matrix is a common tool used to help assess significance using such factors, an example is shown below

Example of a Matrix Showing Significance Related to Sensitivity and Magnitude of Effect

Significance

Sensitivity of Receptor

Magnitude of Effect

Substantial / High

High

High

High

Medium

Medium

High

Moderate / Medium

High

Low

Medium

Medium

Low

High

Slight / Low

Medium

Low

Low

Medium

Low

Low

No Change

High Medium or Low

No Change

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