Assessing environmental impact: guidance

Guidance for policy officials in government to identify and assess the wider environmental impacts of their policy options

The purpose of the environmental impact guidance is to provide guidance and supporting material to enable departments to understand and quantify, where possible in monetary terms, the wider environmental consequences of their proposals. 

This guidance has been developed as a key source for completing the wider environmental impact test in the Impact Assessments template. However, this environmental impact guidance should also be seen as generally applicable to the appraisal of new policies, programmes and proposals. Information from environmental impact assessment is also relevant to the Sustainable Development Impact Test.

Step-by-step guidance

For more detailed guidance on taking account of wider environmental impacts in policy appraisal, see the Step by step guidance (PDF, 129KB, 8 pages). This presents a suggested step by step approach to the assessment of wider environmental impacts of policy options. The emphasis is placed on having a staged and proportionate approach. Hence the early stages focus on scoping work to identify what options have the potential to  give rise to significant wider environmental impacts. 

Where options are not expected to lead to significant wider environmental impacts or are focused on a single environmental impact (eg air quality) then further stages of analysis on other environmental impacts may not be appropriate. Where it is identified that the impacts on wider environmental impacts could be significant and wide ranging from the scoping stage, subsequent steps in the analysis are proposed including the use of an ecosystem services framework. This framework offers a more comprehensive approach to understanding how policies impact on the wider environment.

Impacts specific to policy areas

The following questions are designed to aide thinking about which specific impacts might be relevant for your policy area. By clicking on each question, you can access brief guidance designed to give you the information and the contacts you need to be able to appraise any significant impacts.

Will the policy option:

  • impact significantly on air quality? - Air quality (PDF, 72.8KB, 1 page)  
  • change biodiversity? (either the amount or variety of living species, or the amount, variety or quality of ecosystems) - Biodiversity (PDF, 55.5KB, 3 pages)
  • be vulnerable to the predicted effects of climate change ? - Adapting to climate change (PDF, 88.3KB, 4 pages)
  • involve any material change to the appearance of the landscape or townscape? - Landscape (PDF, 248KB, 14 pages)
  • affect the number of people exposed to noise or the levels to which they’re exposed? - Noise and nuisance (PDF, 75.9KB, 1 page)
  • lead to a change in the financial costs or the environmental and health impacts of waste management? - Waste management (PDF, 72KB, 4 pages)
  • change the degree of water pollution, levels of abstraction of water or exposure to flood risk? - Water including flood risk (PDF, 49.8KB, 6 pages)

Why you need to consider wider environmental impacts

The rationale for taking wider environmental impacts into account is underpinned by existing guidance on policy appraisal. The Treasury Green Book highlights the importance of trying to identify all costs and benefits including environmental.  While impacts on the environment often do not have any market prices, it is important to try and use evidence on non market values attached to environmental impacts where feasible (see Tools for Environmental Valuation).  

Costs and benefits to the environment that have not been valued should also be appraised. All costs and benefits must therefore be clearly described in an appraisal, and should be quantified where this is possible and meaningful. Where it is not possible to provide a monetised or quantified assessment, it is important to provide a qualitative assessment of potential impacts.

How to complete the wider environmental impact test

The summary guidance documents below will help you go through the wider environmental impact test - following this guidance will help to demonstrate that as far as possible the impacts on the wider environment have been taken into account in the policy appraisal process and provide appropriate evidence to present in the impact assessment:

The aim of this is to give you a quick guide to taking a staged and proportionate approach to valuing wider environmental impacts.

Further help

Consideration of the impacts on the environment at an early stage of the policy process will enable an informed assessment. It will ensure that sufficient time is available to assess where wider environmental impacts are significant and quantify and monetise where appropriate.  Following this guidance and demonstrating that the wider environmental impacts of your policy have been taken into account will help to ensure that the policy is consistent with sustainable development principles.

For further support and general advice on taking account of wider environmental impacts in policy appraisal, please contact the Natural Environment Economics team at

Published 9 April 2013