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Environmental assessment (EA) is a participatory decision making support and management instrument in spatial and sectoral policy, plan, programme and project making. It aims at enabling a balanced consideration of economic, social and environmental issues in decision making by pro-actively supporting the transparent ex-ante assessment of alternative and mitigative actions in order to help avoiding negative and enabling positive environmental impacts and outcomes. It was first introduced in the USA through the National Environmental Policy Act (NEPA) of 1969 and is thus the oldest of a range of advocacy decision support instruments, including e.g. sustainability assessment (SA), health impact assessment (HIA) and social impact assessment (SIA).

EA developed, based on the perceived seriousness of adverse environmental impacts of human activities and an inability of existing planning support methods (for example, cost-benefit analysis – CBA) to adequately address those problems. Whilst NEPA did not distinguish between different decision making levels / tiers, aiming at Federal actions, subsequently increasingly a distinction was made between project decisions on the one hand and strategic tier decisions (commonly referred to as policies, plans and programmes – PPPs) on the other. EA of projects is now commonly referred to as environmental impact assessment (EIA), which is reflected in e.g. the wording of the 1985 European Union (EU) EIA Directive (85/337/EEC, amended four times in 1997, 2003, 2009 and 2014) and EA of PPPs as strategic environmental assessment (SEA; in the EU a formal requirement for plans and programmes since 2004 on the basis of Directive 2001/42/EC). Literally all countries in the world now have some experiences with the application of EIA and way over 100 countries have associated formal (usually  legal) requirements. Over 40 countries also have formal SEA requirements, including the 28 member states of the EU. All internationally active development banks and development aid organisation require the application of SEA and EIA in those countries they are engaged in. There are 100s of 1000s of EIAs and SEAs prepared every year globally.

EA has been said to function as a science and an art in that it aims at generating scientifically sound information and predictions by applying a range of suitable assessment methods and techniques, whilst acknowledging the political nature of decision making processes, which it is trying to influence. Current understanding is that in order to be effective, EA needs to deal with framework / systems (i.e. macro) and individual policies, plans, programmes and projects (PPPPs; i.e. micro) levels, providing for:

  1. an overall decision framework, aiming at supporting the consideration of the ‘right issues at the right time’ in spatial and sectoral (e.g. transport, energy and waste) tiered PPPP making hierarchies;
  2.  a participatory decision making support process for a specific policy, plan, programme or project, allowing for stakeholder as well as public involvement and consisting of a range of predefined steps, revolving around the assessment of different alternatives for environmentally sustainable outcomes.
  3. a number of methods and techniques that aim at making policy, plan, programme and project making processes more scientifically rigorous.

Applying EIA and SEA

EIA and SEA are applied to spatial and sectoral public and increasingly also private PPPPs. In order to be effective, EIA and SEA need to systematically assess environmental impacts at all tiers (i.e. all PPPPs). An effective EA framework will be able to uncover any gaps that exist with regards to the consideration of environmental issues within a PPPP system. Ultimately, EIA and SEA thus aim at supporting more transparent, rigorous and systematic decision frameworks. Figure 1 shows an example of a systems’ based transport PPPP decision framework into which SEA and EIA are integrated, outlining the specific focus, tasks, types of impacts to be considered and roles of different administrative levels.

Figure 1: Allocation of tasks within a systems’ based EA framework

In a specific policy, plan, programme or project situation, SEA and EIA are aplied as a decision making support process, consisting of various stages. Frequently, this process includes screening (i.e. a decision on whether or not to conduct a full SEA or EIA process), scoping (deciding on the baseline, the environmental aspects and alternatives to be considered), the preparation of a report, influencing of PPPP decisions and follow-up/ monitoring. This process is iterative (i.e. feedback loops are possible) and is accompanied by consultation and participation of stakholders and the general public at various stages, normally at least at the scoping and report stages. In certain situation, in particular at the highest – policy – tier, more flexible processes may be more suitably applied, including e.g. cabinet decision making.

SEA and EIA also involve using a range of distinct assessment methods and techniques. Some are used for e.g. describing the environmental baseline, some for assessing impacts, some for enabling consultation and participation and some for monitoring and follow-up. Routinely and frequently used methods and techniques include e.g. analogs, checklists, expert opinions, mass balances, matrices and qualitative / quantitative models (see Wood, 1995; Glasson et al, 2005; Fischer 2007).

Theory underlying EA

EA is able to effectively influence decsion making based on three main functions (see Bartlett and Kurian, 1999; Fischer 2003). First, EA influences decisions by providing information, thus helping to achieve informed decisions for a specific PPPP (thus having a short to medium term effect). Second, EA influences decisions by allowing for consultation and participation of stakeholders and the wider public in a structured  and systematic process for a specific PPPP (again having a short to medium term effect). Third, based on formal requirements, EA influences decisions by changing established routines in forcing administrations and those preparing PPPPs to take environmental aspects into account early on (thus having a long term effect).

Practice examples

A wide range of practice examples have been described and evaluated in the professional literature. These include applications from developed and developing countries, different sectors and decision tiers. An overview of SEA research, including case studies until 2012 was provided by Fischer and Onyango (2012). Case studies from EU EIA experiences were elaborated on in a recent issue of the Journal of Environmental Assessment Policy and Management (JEAPM, 2012 (14): 4). In addition to 100s of papers that present practice examples in numerous professional journals (the three main English speaking EA journals being Environmental Impact Assessment Review, Impact Assessment and Project Appraisal and the above mentioned JEAPM), there are numerous books, textbooks (international and national) and monographs on practices from developed and developing countries (see e.g. Glasson et al, 2005; Fischer, 2007; Sadler et al, 2011; OECD, 2012; Dalal-Clayton, 2013; Fischer and Nadeem, 2013).


Bartlett, R.V. and Kurian, P.A., 1999. The theory of environmental impact assessment: implicit models of policy-making. Policy and Politics, 27 (4): 415–433.

Dalal-Clayton, B. 2013, Turning green the strategic way: the role and potential of strategic environmental assessment in securing a green economy, SEA%20and%20Green%20economy%20publshed%20web%20version.pdf, last accessed 13/03/2014.

Fischer, T. B and Nadeem, O. 2013.  Environmental Impact Assessment (EIA) Course Curriculum for Tertiary Level Institutions in Pakistan, IUCN Pakistan, Islamabad, Reports/Draft%20EIA%20Curriculum%20for%20Tertiary%20Level%20Institutions%20in%20Pakistan.pdf, last accessed 13/03/2014.

Fischer, T. B. and Onyango, V. 2012. SEA related research projects and journal articles: an overview of the past 20 years, Impact Assessment and Project Appraisal, 30(4): 253-263.

Fischer, T.B. 2007 Theory and Practice of Strategic Environmental Assessment – towards a more systematic approach, Earthscan, London.

Fischer, T.B. 2003. Strategic environmental assessment in post-modern times, Environmental Impact Assessment Review, 23(2): 155-170.

Glasson, J.; Therivel, R. and Chadwick, A. 2005. Introduction to Environmental Impact Assessment, Taylor and Francis, London.

OECD 2012. SEA in Development Practice – a review of recent experience, OECD, Paris (, last accessed 13/03/2014).

Sadler B., Aschemann, R.; Dusik, J.; Fischer,T. B.; Partidário, M. and Verheem R. (eds). 2011. Handbook of Strategic Environmental Assessment, Earthscan, London.

Wood, C. 2003. Environmental Impact Assessment: a comparative review, Longman, Scientific and Technical, London.

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